criteria for a recommended standard.. OCCUPATIONAL EXPOSURE TO

u. s. department of health, education, and welfare Public Health Service Center for Disease Control National Institute for Occupational Safety and Health June 1976

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 HEW Publication No. (NIOSH) 76-190 PREFACE

The Occupational Safety and Health Act of 1970 emphasizes the need for standards to protect the health and safety of workers exposed to an ever-increasing number of potential hazards at their workplace. The National Institute for Occu­ pational Safety and Health has projected a formal system of research, with priorities determined on the basis of specified indices, to provide relevant data from which valid criteria for effective standards can be derived. Recommended standards for occupational exposure, which are the result of this work, are based on the health effects of exposure. The Secretary of Labor will weigh these recommendations along with other considerations such as feasibility and means of implementation in developing regulatory standards. It is intended to present successive reports as research and epidemiologic studies are completed and sampling and analytical methods are developed. Criteria and standards will be reviewed periodically to ensure continuing protection of the worker. I am pleased to acknowledge the contributions to this report on parathion by members of my staff, the valuable and constructive comments presented by the Review Consultants on Parathion, by the ad hoc committees of the American Academy of Occupational Medicine and the American Conference of Governmental Industrial Hygienists, by Robert B. O’Connor, M.D., NIOSH consultant in occu­ pational medicine, and by Bruce J. Held on respiratory protection. The NIOSH recommendations for standards are not necessarily a consensus of all consultants and professional societies that reviewed this criteria document on parathion. Lists of the NIOSH Review Committee members and of the Review Consultants appear on the following pages.

John F. Finklea, M.D. Director, National institute for Occupational Safety and Health The Division of Criteria Documentation and Standards Development, National Institute for Occupational Safety and Health, had primary responsibility for de­ velopment of the criteria and recommended standard for parathion. The Division review staff for this document consisted of J. Henry Wills, Ph.D., Herbert E. Christensen, D.Sc., and Richard A. Rhoden, Ph.D., with Charles C. Hassett, Ph.D. and Seymour D. Silver, Ph.D. (consultants). The Sequoia Groups, Berkeley, California, developed the basic information for consideration by NIOSH staff and consultants under contract No. HSM-99-72-35. Jon R. May, Ph.D., had NIOSH program responsibility and served as criteria manager.

v REVIEW COMMITTEE NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH Jack Butler, M.D. Acting Director, Office of Extramural Coordination and Special Projects Paul E. Caplan Division of Criteria Documentation and Standards Development Herbert E. Christensen, D.Sc. Deputy Director, Division of Criteria Documentation and Standards Development Steven N. Dereniuk Division of Training and Manpower Development Robert H. Hill, Jr., Ph.D. Division of Physical Sciences and Engineering Keith H. Jacobson, Ph.D. Division of Criteria Documentation and Standards Development Denis J. McGrath, M.D. Former Special Assistant for Medical Criteria Office of Research and Standards Development Frank L. Mitchell, D.O. Division of Criteria Documentation and Standards Development Peter G. Rentos, Ph.D. Office of Extramural Coordination and Special Projects Charles Xintaras, Sc.D. Division of Biomedical and Behavioral Sciences Douglas L. Smith, Ph.D. Western Area Laboratory for Occupational Safety and Health Department of Labor Liaison: Ching-Tsen Bien Office of Standards Occupational Safety and Health Administration NIOSH REVIEW CONSULTANTS ON PARATHION Robert M. Clyne, M.D. Corporate Medical Director American Cyanamid Company Wayne, New Jersey 07470 J. Marshall Magner Senior Entomologist Agricultural Division Monsanto Commercial Products Company St. Louis, Missouri 63166 Donald P. Morgan, M.D., Ph.D. Department of Entomology College of Agriculture University of Arizona Tucson, Arizona 85721 William A. Steffan Senior Industrial Hygiene Engineer Division of Industrial Safety State of California San Francisco, California 94102 J. Henry Wills, Ph.D. Professor of Pharmacology and Toxicology Albany Medical College Albany, New York 12208 Contents Page PREFACE iii NIOSH REVIEW COMMITTEE vi NIOSH REVIEW CONSULTANTS vii I. RECOMMENDATIONS FOR A PARATHION STANDARD ____ 1 Section 1 - Environmental (Workplace Air) ______1 Section 2 - Medical - - ..._ 1 Section 3 - Labeling and Posting ...... ___ 3 Section 4 - Personal Protective Equipment and Protective Clothing ...... ______4 Section 5 - Informing Employees of Hazards from Parathion _ ____ ... ______5 Section 6 - Work Practices ...... 6 Section 7 - Sanitation ... ______9 Section 8 - Monitoring and Recordkeeping Requirements __.... 9 II. INTRODUCTION 11 III. BIOLOGIC EFFECTS OF EXPOSURE 13 Extent of Exposure . 13 Historical Reports ...... 14 Effects on Humans .... _ .... ______15 Epidemiologic Studies ...... ______21 Animal Toxicity ...... __...... ______22 Carcinogenicity, Mutagenicity, Teratogenicity ______32 Correlation of Exposure and Effect . _. .... ______34 IV. ENVIRONMENTAL AND BIOLOGIC METHODOLOGIES ... 37 Air Sampling Methods .... ____ ... ______39 Parathion Analysis ______„ ______40 Plasma and RBC ChE Analysis __._ ___ 41 V. DEVELOPMENT OF STANDARD ______45 Basis for Previous Standards ______45 Basis for the Recommended Environmental Standard ______45 VI. WORK PRACTICES 55 VII. RESEARCH NEEDS 59 VIII. REFERENCES 61 IX. APPENDIX I — Sampling and Calibration Procedures ______69 X. APPENDIX II — Analytical Method for Parathion______71 XI. APPENDIX III — Method for Biochemical Determination of Blood Cholinesterases ______.._ _ . ____ 75

ix XII. APPENDIX IV — Diagnosis and Medical Management of Parathion Poisoning - 79 XIII. APPENDIX V — Material ______81 XIV. APPENDIX VI — Summary of Pertinent California State Pesticide Regulations, 1974 ...... 89 XV. APPENDIX VII —- Summary of Pertinent State (Excluding California) Pesticide Regulations ______...... 91 XVI. TABLES ______93

x I. RECOMMENDATIONS FOR A PARATHION STANDARD

The National Institute for Occupational Safety (b) Sampling and Analysis and Health (NIOSH) recommends that employee Procedures for collection and analysis of en­ exposure to parathion in the workplace be con­ vironmental samples shall be as provided in Ap­ trolled by adherence to the following sections. The pendices I and II or by any method shown to be at standard is designed to protect the health and least equivalent in accuracy, precision, and sen­ safety of workers for up to a 10-hour work shift,sitivity to those specified. 40-hour workweek during a working lifetime. Compliance with all sections of the standard Section 2—Medical should prevent adverse effects by parathion on the Medical surveillance (biologic monitoring and health and safety of employees. The standard is medical management) shall be made available to measurable by techniques that are valid, workers as outlined below. Physicians responsible reproducible, and available to industry and govern­ for workers who may be occupationally exposed to ment agencies. Sufficient technology exists to per­ parathion should be familiar with the information mit compliance with the recommended standard. contained in Appendix IV which describes the The criteria and standard will be subject to review diagnosis and treatment of intoxication by this and revision as necessary. compound. “Parathion” is defined as 0,0-diethyl O-p- (a) Medical Examinations nitrophenyl phosphorothioate, regardless of (1) Preplacement and periodic medical ex­ production process, alone or in combination with aminations shall include: other compounds. “Occupational exposure to (A) Comprehensive initial or interim parathion” is defined as employment in any area medical and work histories. in which parathion or materials containing (B) A physical examination which shall parathion, alone or in combination with other sub­ be directed towards, but not limited to, evidence stances, is produced, packaged, processed, mixed, of frequent headaches, dizziness, nausea, tightness blended, handled, stored in large quantities, or ap­ of the chest, dimness of vision, and difficulty in plied. If employees are potentially exposed tofocusing the eyes. Those workers with a history of other chemicals, such as pesticide vehicles, glaucoma, cardiovascular disease, hepatic disease, diluents, or emulsifiers, or other pesticides, provi­ renal disease, or central nervous system abnormali­ sions of any applicable standards for such other ties should be considered for exclusion from as­ chemicals shall also be followed. Adherence to all signments requiring exposure to parathion. provisions of the standard is required in work­ (C) Initial medical examinations shall be places using parathion regardless of the airborne made available to all workers within 60 days of the parathion concentration because of serious effects promulgation of this recommended standard. produced by contact with the skin, mucous mem­ (D) Periodic examinations shall be made branes, and eyes. Since parathion does not irritate available on an annual basis or at some other in­ or burn the skin, no warning of skin exposure is terval determined by the responsible physician. likely to occur. However, parathion is readily ab­ (E) Determination, at the time of the sorbed through the skin, mucous membranes, and preplacement examination, of a baseline or work­ eyes and presents a potentially great danger from ing baseline erythrocyte cholinesterase activity these avenues of absorption. It is extremely impor­ (See Section (b) Biologic Monitoring). tant to emphasize that available evidence indicates (F) A judgment of the worker’s physical that the greatest danger to employees exposed to ability to use negative or positive pressure respira­ parathion is from SKIN CONTACT. tors as defined in 29 CFR 1910.134. (2) Emergency first-aid services shall be Section 1—Environmental (Workplace Air) established, under the direction of the responsible (a) Concentration physician, to provide care to any worker acutely Occupational exposure to parathion shall be intoxicated by parathion (See Appendix IV). controlled so that no employee is exposed to (3) Appropriate medical services and sur­ parathion in a concentration greater than 0.05 veillance shall be provided to any worker with ad­ mg/m3 of air determined as a time-weighted verse health effects reasonably assumed or shown average (TWA) exposure for up to a 10-hour to be due to occupational exposure to parathion. work shift and a 40-hour workweek. (4) Medical records shall be maintained for 1 all workers occupationally exposed to parathion (C) Subsequent to the determination of a and such records shall be kept for at least 5 years preexposure or working baseline, each employee after termination of employment. occupationally exposed to parathion shall have his (5) Pertinent medical information shall beerythrocyte cholinesterase activity determined at available to the designated medical representatives 4-week intervals, except for those employees in of the Secretary of Health, Education, and Wel­ the following occupations: (1) mixers, loaders, fare, of the Secretary of Labor, of the employee orground applicators, flaggers, and manufacturing or former employee, and of the employer. formulating employees working with other than (b) Biologic Monitoring closed production, mixing, blending, transfer, and (1) Definitions packaging systems—all of whom shall be tested at (A) “Preexposure baseline” for erythro­ 1-week intervals. This 1-week interval shall be cyte cholinesterase is defined as the mean of 2 reduced to testing every 3 days for any employee cholinesterase activity determinations, each of working with parathion for a period exceeding 12 which is derived from a separate sample of blood hours during any workday. This shorter interval taken at least I day apart, after a period of at least shall be maintained until at least one entire work­ 60 days without known exposure to any week has elapsed without a workday exceeding 12 cholinesterase-inhibiting compounds. If the deter­ hours, (2) personnel who clean or repair equip­ minations produce values differing by more than ment or clean parathion spills and aerial applica­ 15%, additional determinations on new samples tors (ie, agricultural pilots) not engaged in loading must be performed until successive tests do not operations shall be tested at 2-week intervals. differ by more than 1 5%. (D) Unacceptable absorption of (B) “Working baseline” for erythrocyte parathion indicating a failure of control cholinesterase is defined as the mean of 2 procedures and/or work practices is demonstrated cholinesterase activity determinations, each of when the enzymic activity of erythrocyte which is derived from a separate sample of blood cholinesterase is decreased to between 60-70% of taken at least 1 day apart and differing by no more the employee's preexposure baseline or working than 15%, or the arithmetic mean of normal values baseline level. The employee shall be advised of for an appropriate control population of adults for this finding and an industrial hygiene survey shall that laboratory, whichever is higher. A “working be conducted in the workplace of the affected em­ baseline” is determined only for an individual ployee unless the cause of the exposure is known whose work history does not permit a preexposure and corrective action has been initiated. This sur­ baseline to be determined as specified in para­ vey shall include an assessment of the dermal ex­ graph (b)( 1 )(A) of this section. posure potential. Based on the results of this sur­ (C) “Mean of normal values” is defined vey. necessary corrective action shall be accom­ as the arithmetic mean of erythrocyteplished. cholinesterase activities for healthy adults as deter­ In addition an employee whose erythrocyte mined by the laboratory’s experience with re­ cholinesterase determination, as required by para­ peated analyses, but which is not inconsistent with graph (b)(2) of this section or (a)(5) of Section 6, the mean baseline activities presented in Table XI- indicates that his erythrocyte cholinesterase activi­ 2 of Appendix III. ty is decreased to 60% or below of his preexposure (2) Routine Monitoring baseline or working baseline shall be removed (A) All employees who are to be occupa­ from potential exposure to parathion and placed tionally exposed to parathion shall have preexpo­ under medical observation. In such cases, an in­ sure erythrocyte cholinesterase baselines deter­ dustrial hygiene survey shall be conducted in the mined whenever their work history allows an accu­ workplace of the affected employee unless the rate preexposure determination, as specified in cause of the exposure is known and corrective ac­ paragraph (b)(1)(A) of this section. Those new tion has been taken. This survey shall include an employees with work histories precluding preexpo­ assessment of the dermal exposure potential. sure baseline cholinesterase determinations shall Based on the results of this survey necessary cor­ have working baseline determinations performed. rective action shall be accomplished. (B) Within 60 days after the effective date of a standard based on this recommendation, (E) An employee who has been removed all present employees occupationally exposed tofrom parathion exposure shall not be allowed to parathion shall have working baseline erythrocyte return to work involving occupational parathion cholinesterase activity determined. exposure until his erythrocyte cholinesterase ac­ 2 tivity has returned to at least 75% of the working EMERGENCY INFORMATION or preexposure baseline values or unless the responsible physician has approved his return. (F) Each employee shall be given a copy If liquid gets on skin, wash immediately of the results of his initial and periodic tests, and with alkaline soap and water and call a of any special cholinesterase test results as soon as physician. If clothes become con­ possible after the test, plus an interpretation. taminated, remove at once. Then wash (3) Blood Collection and Analysis your body with soap and water and call a Procedures for collection and analysis of blood physician. If sickness occurs while han­ samples for RBC ChE activity shall be as provided dling materials containing parathion, or in Appendix III or by any method shown to be at after handling such materials, call a physi­ least equivalent in accuracy, precision, and sen­ cian. NOTE: Poisoning symptoms may sitivity to those specified. occur several hours after work ends. If possible, take this label to the physician Section 3—Labeling and Posting along with the patient. (a) Labeling Containers of parathion used in the workplace IN CASE OF FIRE, use supplied-air shall be labeled with at least the following infor­ respirator. Burning may produce highly mation: poisonous combustion products. DANGER! POISON In case of spills, accidental discharges, leaks, ruptures, or other sources of con­ CONTAINS PARATHION tamination of equipment, facilities, or EXTREME HEALTH HAZARD (includes skin) ground, place contaminated area or items f If Swallowed under continuous surveillance, then decon­ CAN BE FATAL j If Left on Skin taminate with strong alkali or other suita­ [ If Heated and Inhaled ble decontaminating materials.

If parathion is dissolved in a combustible solvent, (b) Posting the label shall include a statement of flamma- ( 1 ) The following sign shall be posted in a bility appropriate to the solvent. readily visible location at or near all entrances to The following list of safe work practices and manufacturing, formulating, and storage areas in emergency information shall be made available to which there is occupational exposure to parathion: each employee as informational material. POISON AREA SAFE WORK PRACTICES PARATHION Do NOT breathe vapor, mist, or dust or allow to get f If Swallowed into eyes, on skin, or on clothing. Do not rub eyes or CAN BE FATAL J If Left on Skin face with hands or clothing. [ If Heated and Inhaled When possibility of contact exists: Use required personal protective equipment Wear full-body coveralls or impervious apron, goggles, and clothing. impervious boots and gloves, and, if required, If SKIN contact occurs, wash immediately a respirator. with alkaline soap and water and call a physician. WARNING — Can penetrate leather or canvas shoes If CLOTHES are contaminated, go to a clean area and sneakers. and remove quickly. Use fresh clothing daily. Wash skin with soap and water. Shower with soap and water before leaving work. Put on clean clothes and call a physician. Do not wear work clothes home. DO NOT SMOKE, EAT, OR SLEEP IN AREA. Wash hands thoroughly with soap and water before eat­ ing, chewing gum, smoking, defecating, or urinating. Store food and tobacco away from work area. Keep Warning signs shall be printed in English and in containers tightly closed whenever unattended. Protect the predominant language of non-English-reading concentrated parathion from all sources of ignition. Do employees. Employees unable to read posted not warm concentrated parathion containers with open warnings and labels and those unfamiliar with En­ flame. Do not smoke while handling parathion. glish or with the predominant non-English lan­ 3 guage shall receive periodic training sufficient to pervious gloves. Employees applying parathion by ensure their understanding of the contents of the open-cockpit aircraft shall be provided with, and label and poster specified in this section, and to required to wear, full-body coveralls or impervious provide a continuing reminder of these contents. rainsuit, goggles, and impervious gloves. (2) The following poster shall be securely (5) Employees acting as flaggers (other attached beside the entrance to any vehicle (eg, than those flagging from enclosures) in the aerial truck, freight car) used to transport parathion at application of parathion shall be provided with, all times that parathion is contained therein: and required to wear, full-body coveralls or imper­ vious rainsuit, a protective head and neck covering DANGER — POISON (preferably wide-brimmed and waterproof), imper­ vious footwear, and impervious gloves. CONTAINS PARATHION (6) Where toxic residues present a reasona­ ble potential for exposure, employees entering IF LIQUID OR POWDER HAS LEAKED, areas treated with parathion shall be provided DO NOT ENTER with, and required to wear, impervious gloves, full- CAN BE ABSORBED THROUGH SKIN body coveralls or impervious rainsuit, face shield if OR BY BREATHING foliage is likely to contact the face, and impervious footwear. IF SKIN CONTACT OCCURS, (7) Employees (such as cleanup personnel) WASH IMMEDIATELY entering areas contaminated with parathion shall WITH ALKALINE SOAP AND WATER be provided with, and required to wear, impervi­ AND CALL A DOCTOR AT ONCE ous gloves, full-body coveralls or impervious rain­ suit, impervious footwear, impervious apron, and Section 4—Personal Protective Equipment and such other personal protective equipment as may Protective Clothing be required for adequate protection against the particular hazards presented. (a) Skin Protection (8) Laundry personnel handling clothing (1) Unless separately provided in this sec­ contaminated with parathion shall be provided tion, an employee who engages in filling, pouring, with, and required to wear, impervious gauntlet mixing, formulating, loading, applying, or other­ gloves, impervious shoes, and, in addition to ordi­ wise handling parathion (including in open-system nary clothes, an impervious apron. manufacturing processes) shall be provided with, (9) The employer shall ensure that all per­ and required to wear, protective head covering; sonal protective devices are inspected regularly goggles or face shield; impervious gloves; full-body and maintained in clean and satisfactory working coveralls, impervious apron, or impervious rain- condition. suit; and impervious footwear. Impervious gloves (10) Protective clothing shall not be taken should have reverse gauntlets and coveralls should home by employees. The employer shall provide be of a closely-woven material (siliconized fabric for maintenance and laundering of protective [nylon or cotton] is especially protective) withoutclothing. cuffs. Whenever the word impervious appears in (b) Respiratory Protection this document, it means highly resistant to the ( 1 ) Engineering controls shall be used penetration of parathion. wherever feasible to maintain airborne parathion (2) Employees handling sealed, nonleaking concentrations below the workplace air limit containers of parathion shall be provided with, and specified in Section 1(a). Compliance with the required to wear, full body coveralls and impervi­ workplace environmental limit may not be ous gloves. achieved by the use o f respirators except: (3) Employees operating open equipment (A) During the installation, testing, main­ for ground (non-aerial) application of parathion tenance, or repair of required engineering con­ shall be provided with, and required to wear, a trols. protective head covering, preferably wide-brimmed (B) For nonroutine operations, such as and waterproof, or face shield, impervious gloves, maintenance or repair activities, where brief expo­ full-body coveralls or an impervious rainsuit, and sure to parathion at concentrations in excess of impervious footwear. the permissible exposure limit could occur. (4) Employees applying parathion by (C) During emergencies. closed-cockpit aircraft shall be provided with im­ 4 (2) When a respirator is permitted by para­ (G) The employer shall ensure that graph (b)(1) of this section, it shall be selected respirators are adequately cleaned and maintained, and used in accordance with the following require­ and that employees are instructed on the use of ments: respirators assigned them and on methods for (A) For the purpose of determining the leakage testing. type of respirator to be used, other than supplied- (H) Respirators specified for use in air positive pressure respirators, the employer shall higher concentrations of airborne parathion may make a determination of the atmospheric concen­ be used in atmospheres with lower concentrations. tration of parathion in the workplace initially (and (I) Respirators, except cooled supplied- thereafter whenever pertinent working conditions air type, shall not be used for more than 15 are altered) and shall choose the appropriate minutes if ambient temperature exceeds 85°F in respiratory protective device specified in Table 1-1. the particular workplace, except in emergencies. The employer shall ensure that no employee is (J) Where an emergency may develop being exposed to parathion in excess of the limit which could result in overexposure of employees specified in Section 1(a) because of improper to parathion, the employer shall provide respirato­ respirator selection, fit, use, or maintenance, or ry protection as indicated in Table 1-1. because of changes in working conditions. (3) For purposes of this section, the appli­ (B) Employees experiencing breathing cation of parathion formulations is not to be con­ difficulties while wearing respiratory protective sidered a nonroutine operation for which respira­ devices shall be medically examined to determine tors may be used in exposure situations where the their ability to wear such devices. If it is deter­ environmental limit is exceeded. Engineering con­ mined that an employee cannot breathe adequate­ trols, such as enclosed filtered-air tractor cabins ly while wearing a respirator, the employee shall and aircraft cockpits, shall be used where the en­ not be allowed to work in any operation requiring vironmental conditions encountered or the appli­ the use of a respirator. This provision shall not re­ cation method selected present a reasonable lieve the employer of any of the requirements oflikelihood of the environmental limit being ex­ Section 2(a). ceeded. Where filtered-air enclosures are used, air (C) A respiratory protective program levels of parathion shall be regularly monitored to meeting the requirements of 29 CFR 1910.134 ensure compliance with the standard. and 30 CFR 1 1 which incorporates the American National Standard Practices for Respiratory Pro­ Section 5—Informing Employees of Hazards from tection Z88.2-1969 shall be established and en­ Parathion forced by the employer. (a) Before work involving occupational expo­ (D) The employer shall provide respira­ sure to parathion begins, all new or reassigned em­ tors in accordance with Table 1-1 and shall ensure ployees shall be informed of the hazards of that the employee uses the respirator provided. parathion, relevant symptoms of overexposure to (E) Respiratory protective devices parathion, appropriate emergency procedures, and described in Table 1-1 shall be those approved the conditions and precautions required for safe under the provisions of 29 CFR 1910.134 and 30 handling of parathion. CFR 11. (b) Within 30 days after promulgation of a (F) Canisters or cartridges shall be standard based on these recommendations, all em­ discarded and replaced with fresh canisters or car­ ployees whose duties currently involve potential tridges in accord with the manufacturer’s specifi­ exposure to parathion shall be informed as in para­ cations, or if the odor of parathion, parathion-con-graph (a) of this section. taining formulations, diluents, emulsifiers, or sol­ (c) A program of employee education shall vents is detected while using the respirator, or if a be instituted within 30 days after the effective date breakthrough-indicator (if any) indicates the ab­ of a parathion standard. The program shall be sorbent is saturated, whichever occurs first. Filters designed to ensure that all employees occupa­ shall be changed whenever canisters or cartridges tionally exposed to parathion understand and are changed, or after every 4 hours of use, or if remain aware of job hazards as well as emergency, breathing becomes difficult, whichever occurs first. maintenance, and cleanup procedures, and that Unused canisters or cartridges shall be discarded they know how to correctly use and maintain and replaced when the seals are broken, or on the respiratory protective equipment and protective expiration of the manufacturer’s recommended clothing. The training shall be repeated at least an­ storage life if the seals are unbroken. nually after the employee’s initial training required 5 TABLE 1-1 RESPIRATOR SELECTION GUIDE FOR PROTECTION AGAINST PARATHION Concentration of Parathion Respirator Type 0.5 mg/ eu m or less Half-mask pesticide respirator. or Type C supplied-air respirator, demand type (negative pressure), with half-mask faccpiece 2.5 mg/cu m or less Fullface gas mask (chin-, chest-, or back-mounted type) or Type C supplied-air respirator, demand type (negative pressure), with full facepiece. 50 mg/cu m or less Type C supplied-air respirator, continuous flow type with full facepiece or suit or Pressure-demand type respirator with full facepiece and impervious plastic shroud Emergency Self-contained breathing apparatus with positive pressure (includes entry into in full facepiece vessels, bins, or other or containers which are Combination supplied-air respirator, pressure demand probably contaminated type with auxiliary self-contained air supply with parathion) under this paragraph. person or 100 gallons, whichever is greater, plus (d) In addition to the requirements of para­ alkaline soap and towels, for use in emergencies. graph (c) above, employees occupationally ex­ Emergency water supplies are not required in posed to parathion shall be kept currently in­ agricultural aircraft. Tractors shall have at least 10 formed through posting as specified in Section gallons of water stored in closed containers. Mix­ 3(b) and shall be instructed as to the availability ing vehicles shall have at least 20 gallons of water of biologic monitoring information. The informa­stored in closed containers. tion specified in Section 2(b)(2) shall be kept on (3) Parathion-manufacturing, -formulating, file and shall be readily accessible to each em­ and fixed mixing facilities shall have emergency ployee at or near each workplace where exposure showers. to parathion may occur. In addition, each em­ (4) Whenever parathion contaminates ployee shall be informed of his or her biologic clothing or personal protective equipment, other monitoring results as specified in Section than the outside of impervious clothing or respira­ 2(b)(2)(F). tory protective devices, the employees shall move (e) Information as required shall be recorded away from the possibility of further exposure. The on the “Material Safety Data Sheet” shown in Ap­ contaminated articles shall be immediately pendix V, or on a similar form approved by the removed and the employee required to wash with Occupational Safety and Health Administration, alkaline soap and water. US Department of Labor. (5) Before removing externally con­ taminated impervious clothing, its surface shall be Section 6—Work Practices washed with alkaline soap and water or other (a) Emergency Procedures decontaminant of equal or superior effectiveness. ( 1 ) Each employer shall contact and advise (6) When an employer, a supervisor, or the a physician, or other nearby medical service, that affected employee suspects overexposure to an emergency arising from exposure to parathion parathion (eg, known exposure, obvious signs or exposure can occur. symptoms of poisoning), the employee shall be (2) Unless otherwise specified in this para­placed under medical observation until a deter­ graph, employees occupationally exposed tomination is made by the physician in accordance parathion shall have provided to them in a readily with Section 2(b)(2) that the employee is capable accessible site either 25 gallons of water for each of returning to work. 6 (7) Persons responsible for fire protection (H) Loading equipment shall be fitted shall be informed that formulations of parathion in with an automatic shutoff device to prevent over­ combustible solvents are being used, of the high filling. toxicity of the products of combustion, and of the (I) Tank covers shall be so constructed necessity for using supplied-air respirators in sup­ to minimize the possibility of contents spilling in pressing fires involving parathion. the event of rollover or aerial accident. (8) Any emergency or accidental release (3) Ventilation (eg, application to incorrect field) of parathion (A) If used, ventilation systems shall be from agricultural aircraft shall be reported im­ designed to remove parathion from the breathing mediately to people resident in the area and to ap­ zones of exposed workers and to prevent the accu­ propriate local regulatory or health officials. mulation and recirculation of parathion in the (b) Engineering Controls workplace. (1) Engineering controls, such as process (B) Exhaust ventilation systems discharg­ enclosures, filling equipment with automatic shu- ing into outside air shall conform to applicable toff, mechanical metering and transferring devices, local, state, and federal air pollution regulations. and ventilation systems, shall be used if necessary (C) A program of periodic preventive to ensure that the workplace environmental limit maintenance, cleaning, and inspection shall be specified in Section 1(a) is not exceeded, and to established to ensure maximum effectiveness of minimize skin exposure to parathion. ventilation systems. This program shall include air­ (2) Control of Unit Operations flow measurements, inspection of ductwork for (A) Controls of unit operations of leaks, and examination of the collecting ele- equivalent or superior effectiveness may be sub­ ment(s). These procedures shall be performed be­ stituted for those specified in paragraphs (B) fore manufacturing or formulating operations through (1) below. begin and at least twice monthly during manufac­ (B) All fittings, hoses, tubing, pumps, ture or formulation. valves, and associated equipment operated at posi­ (c) Storage tive pressure shall be be sufficient to withstand 2Vz (1) All locations in which parathion is times the maximum pressure normally encountered stored, or where access is not otherwise limited, and shall be examined at least weekly for leaks shall be fenced and locked and shall be posted as and other signs of deterioration. specified in Section 3(b). (C) All hoses, pipes, and tubing used for (2) Provisions for the storage of containers filling tanks on loading or application vehicles with of parathion or its formulations are given in 29 parathion shall be equipped with quick-acting shu- CFR 1910.106. All parathion containers shall be toff valves or other devices at the discharge ends protected from heat, corrosion, mechanical to prevent dripping. damage, and sources of ignition. (D) Back siphoning by hoses used for (3) Containers of parathion shall be in­ filling vessels, tanks, or other containers with spected upon receipt, and at least monthly parathion, or for adding any other liquid if the thereafter, for corrosion, leaks, breaks, tears, or container already contains parathion, shall not be other defects. permitted. (4) Partially-full and empty parathion con­ (E) When positive displacement pumps tainers shall be tightly closed and kept in locked are used with hoses, pipes, or tubing equipped storage areas until disposed of properly, except with shutoff valves at the discharge end, a relief where direct supervision is maintained continu­ device shall be installed to bypass liquid back to ously. the low-pressure side of the system in order to (5) Parathion shall only be stored in con­ prevent rupture of hoses, pipes, tubing, or pumps. tainers which bear the label required in Section (F) All application equipment with 2 or 3(a). more nozzles shall have the distribution manifold (6) Containers which are normally used for shielded to minimize operator exposure in the storage or preparation of food, feed, or drink shall event of malfunction. not be used for storage of parathion. (G) Opaque tanks used for mixing, load­ (7) No persons shall be allowed to eat, ing, or application of parathion shall be equipped sleep, or smoke in any area in which parathion is with indicators of the level of liquid within the stored. tank. (8) Outdoor storage facilities shall be 7 located at least 20 feet from any dwellings or (6) Unless otherwise provided by local, populated area and shall be equipped with a sprin­ state, or federal regulation, clothing, rags, bags, or kler system, where feasible. fiber drums heavily contaminated with parathion (d) Personal Hygiene shall be incinerated with adequate precautions to (1 ) The employer shall provide a changing prevent inhalation of potentially toxic fumes, area where street clothes may be stored free from vapors, or combustion products, or the materials contamination by parathion. shall be tak^n to a sanitary landfill and properly (2) All required personal protective disposed of. clothing and protective equipment shall be pro­ (7) AN empty containers contaminated vided and laundered or cleaned daily by the em­ with parathion that are to be disposed of in a sani­ ployer. The employer shall ensure that all impervi­ tary landfill shall first be decontaminated with a ous personal protective clothing is free from strong alkaline solution, or with an equivalent or cracks, pinholes, or other signs of deterioration. superior decontaminating solution, and then punc­ Personal protective clothing grossly contaminated tured before disposal. with parathion shall be decontaminated and laun­ (8) Empty metal drums or containers con­ dered separately from other clothing. taminated with parathion that are to be reclaimed (3) The employer shall make extra clothes shall be decontaminated with a strong alkaline available at each work site for use when protective solution or with an equivalent or superior decon­ or personal clothing becomes contaminated with taminating solution before shipment. The parathion. reclaimer shall be informed of the parathion con­ (4) Employees occupationally exposed to tamination. parathion shall be required to wash hands and face (9) Whenever it is necessary for an em­ with alkaline soap and water before eating, drink­ ployee to perform maintenance or repair work on ing, smoking, or using toilets. parathion-contaminated equipment, such as a ves­ (5) Employees occupationally exposed to sel, pump, valve, pipe, nozzle, etc, the equipment parathion shall be required to take a shower at the shall be decontaminated with a strong alkaline end of each workday before leaving work. The solution, or with an equivalent or superior decon­ employer shall provide alkaline soap and clean taminating solution, before maintenance or repair towels. is undertaken. (e) Housekeeping, Decontamination, and (10) Reusable clothing that has been worn Waste Disposal during the work period shall be placed in a plastic (1) All parathion spills shall be cleaned up bag or container and labeled with a suitable warn­ as soon as possible. Continuous surveillance of ing of possible contamination with parathion. spills shall be provided until decontamination is (f) Other Work Practices completed. Contaminated areas shall be roped off (1) Employees handling parathion concen­ or access to them otherwise prevented. They shall trates shall work in teams. In addition, regardless also be posted. of the concentration of the material, all mixers, (2) Spills of parathion on floors shall be loaders, flaggers, and applicators must maintain absorbed with absorbing clay. Sweeping compound periodic communication with a person capable of shall be utilized to facilitate the removal of all visi­ summoning emergency aid if needed. ble traces of parathion-contaminated clay. (2) Employees potentially exposed to (3) All floors that may be contaminated by parathion while spraying shall remain upwind from parathion shall be decontaminated with a strong the spray whenever possible. alkaline solution, or with an equivalent or superior (3) No aerial applicator may mix or load decontaminating solution, at least weekly. pesticides containing parathion in whole or in part, (4) Equipment or fixtures contaminated unless closed mixing or loading systems are used. with parathion, including operator compartments This provision allows an aerial applicator to super­ or control positions on application and loading vise mixing or loading operations involving open equipment, shall be washed with a strong alkaline systems. solution, or with an equivalent or superior decon­ (4) Materials containing parathion shall not taminating solution, as soon as possible. be used when testing mixing, loading, or applica­ (5) Drip pans containing absorbent materi­ tion equipment for leaks, or when testing for al shall be utilized to facilitate decontamination in clogged valves, lines, or strainers, or when equip­ locations where leakage is likely to occur. ment is calibrated.

8 (5) Dispersal equipment containing Monitoring shall continue until two consecutive parathion may not be turned on outside the area samplings, at least a week apart, indicate that em­ to be treated. Except in an emergency, jettison or ployee exposure no longer exceeds the TWA en­ otherwise dumping of parathion from application, vironmental limit specified in Section 1(a). mixing, or loading vehicles shall be prohibited un­ Monthly monitoring may then be resumed. less proper disposal procedures are followed. (2) Air samples shall be collected in the (6) Employees piloting agricultural aircraft breathing zone of employees to permit calculation may not fly through the drift of an application, norof TWA values for every parathion exposure area. shall they start or continue an application if wind For each TWA determination, a sufficient creates a drift hazard to themselves or others, nor number of samples shall be taken to characterize shall they spray or dust over waterways, canals,each employee"s exposure during each work shift. buildings, dwellings, vehicles, or persons, including Variations in work and production schedules shall flaggers. be considered in deciding when samples are to be collected. The number of representative TWA Section 7—Sanitation determinations for an operation or process shall be (a) Food Facilities based on the variations in location and job func­ Storage, preparation, dispensing (including by tions of employees in relation to that operation or vending machines), or eating and drinking of foods process. or beverages shall be prohibited in areas where (b) Recordkeeping parathion is present. Employees may not carry (1) Sampling records shall be maintained food or beverage while working in these areas so that exposure information is available for in­ because of the risk of contamination. The em­ dividual employees. These records shall indicate, ployer shall provide an area free from parathion in addition to the results of air sampling, the type contamination in which employees may storeof personal protective device, if any, in use by lunches and other foodstuffs or tobacco products. each employee at the time of sampling. Each em­ (b) Smoking ployee shall be allowed to obtain information on Smoking shall be prohibited in areas where his or her own environmental exposure. parathion is present. Employees may not carry (2) Records shall be maintained and shall tobacco products while working in these areas include sampling and analytical methods, types of because of the risk of contamination. respiratory devices used, and TWA airborne con­ centrations found. In addition, the following Section 8—Monitoring and Recordkeeping records shall be maintained for each employee oc­ Requirements cupationally exposed to parathion: (a) Environmental Monitoring (A) Preexposure baseline erythrocyte (1) Each employer involved in the manu­cholinesterase activity or working baseline facture or formulation of parathion shall monitor cholinesterase activity, whichever is applicable. environmental air levels of parathion at least (B) All cholinesterase activities measured monthly, except as specified otherwise by a profes­ during employment. sional industrial hygienist. The initial monthly en­ (C) Medical records compiled during em­ vironmental air sampling shall be completed within ployment (including preplacement examinations) 6 months of the effective date of a standard incor­ in accordance with Section 2(a). porating these recommendations. If monitoring of (3) Records required by this section shall an employee’s exposure to parathion reveals that be maintained for 5 years after the worker’s em­ he is exposed at concentrations in excess of the ployment has ended and shall be made available to recommended TWA environmental limit, control the designated medical representatives of the measures shall be initiated and the employee shall Secretary of Health, Education, and Welfare, of be notified of his exposure and of the control mea­ the Secretary of Labor, of the employer, and of sures being implemented to correct the situation. the employee or former employee.

9 II. INTRODUCTION

This report presents the criteria and the recom­ existing technology. Although an environmental mended standard based thereon which were limit is recommended herein, because of the ex­ prepared to meet the need for preventing occupa­ tensive use of parathion in agriculture, emphasis tional diseases arising from exposure to parathion. has been placed on proper work practices as a The criteria document fulfills the responsibility of means of minimizing parathion exposure and on the Secretary of Health, Education, and Welfare, the appropriate biologic monitoring and medical under Section 20(a)(3) of the Occupational Safety surveillance of employees who work with and Health Act of 1970 to “ . . . develop criteria parathion. Also, the recommended standard dealing with toxic materials and harmful physical emphasizes the provision of sanitary facilities and agents and substances which will describe ex­ the apprisal of all employees of the hazards of posure levels at which no employee will suffer im­ parathion and the importance of proper sanitary paired health or functional capacities or and work practices generally. diminished life expectancy as a result of his work In addition to the obvious hazards attending ex­ experience.” posure to concentrated parathion, more subtle The National Institute for Occupational Safety problems are posed by the potential exposure of and Health (NIOSH), after a review of data and large numbers of agricultural workers to parathion consultation with others, formalized a system for residues on crops and in the agricultural work­ the development of criteria upon which standards place in general. Numerous documented instances can be established to protect the health of workers of multiple “picker” poisonings exist but the fac­ from exposure to hazardous chemical and physical tors involved in the causation of these incidents agents. Criteria for a recommended standard are only poorly understood. To protect workers should enable management and labor to develop from these hazards, the field reentry concept has better engineering controls resulting in more been given much consideration during the period healthful work environments and mere compliance 1972-76. Reentry intervals define the time with the recommended standard should not be between application of the pesticide and entry of used as a final goal. workers for any activity involving extensive con­ In evaluating occupational hazards and setting tact with the crop. The protection of field workers priorities, it was determined that parathion is one from the potentially hazardous effects of parathion of the chemicals of greatest immediate concern. and parathion-metabolite residues on fruits, Sporadic cases of occupational and accidental vegetables, and foliage through the establishment poisoning due to concentrated parathion and of safe reentry intervals has been intentionally parathion and/or metabolite residues on fruits, omitted from this recommended standard because vegetables, and foliage have been reported. Since of standards promulgated and enforced by the En­ the late 1940’s, when parathion was introduced in vironmental Protection Agency(Federal Register the United States for use as an , an 39:16888-91, May 10, 1974). ever-increasing literature on the compound, its The recommended standard was not designed properties, and many aspects of its use has accu­ for the population-at-large and any extrapolation mulated. beyond general occupational exposures is not war­ These criteria for a standard for parathion are ranted. part of a continuing series of criteria developed by The development of the recommended standard NIOSH. The proposed standard applies only to for occupational exposure to parathion has those processes and operations involving the revealed deficiencies in the data base in the fol­ manufacture, processing, and use of parathion as lowing areas: (1) epidemiologic studies of workers applicable under the Occupational Safety and exposed to parathion for extended periods; (2) Health Act of 1970. chronic animal exposure studies at low levels of These criteria were developed to ensure that the parathion with emphasis on CNS effects; (3) standard based thereon would (1) protect em­ animal experiments to determine the carcinogenic, ployees against development of acute and chronic mutagenic, and teratogenic potential of parathion parathion poisoning, (2) be measurable by for man; (4) the value of electromyography in as­ techniques that are available to industry and sessing the toxic potential of parathion; and (5) governmental agencies, and (3) be attainable with improvement of the sampling method for personal 11 monitoring. A more complete discussion of these and several other gaps is presented in Chapter VII—Research Needs.

12 III. BIOLOGIC EFFECTS OF EXPOSURE

Parathion (0,0-diethyl O-p-nitrophenyl malian acute toxicity than parathion 5 Partly a.-.j phosphorothioate) belongs to a family of or-consequence of the increasing use of competing ganophosphorus (OP) compounds, members of , the amount of parathion manufac­ which act directly or indirectly as cholinesterase tured in this country dropped from a high figure of (ChE) inhibitors. Direct inhibitors, such as paraox- 20,000,000 pounds (estimated) in 1968 to on, are capable of reacting directly with the ChE 15,259,000 in 1970.2 enzymes thereby inactivating them. Parathion is Koelle1 stated that parathion has probably been called an indirect inhibitor because it must be con­ responsible for more cases of accidental poisoning verted in the environment or in vivo to the and death than any other OP pesticide compound. (ie, active form) before it can effectively inhibit The magnitude of poisoning by parathion from ChE’s. Organophosphorus insecticide usage is in­ occupational exposures is more difficult to assess creasing today as a result of the present restric­ than that from accidental poisonings. A relation tions against the use of DDT and related, per­ ship between occupational poisonings due to pesti­ sistent, chlorinated hydrocarbon insecticides. cides and all other poisonings for the State of Parathion is converted in the body in part to California can be obtained from California Depart­ , a strong inhibitor of the enzyme ment of Public Health Reports.6,7 Undei California .1 Upon inhibition of this en­ law,6 each physician who attends an injured em zyme in the tissues, , the substance ployee must file a report, the Doctors’ First Report responsible for transmission of nerve impulses in of Work Injury, with the Division of Labor much of the nervous system, accumulates, produc­ Statistics and Research in the California Depart­ ing an initial overstimulation and subsequent ment of Industrial Relations (State of California blockage of nerve stimuli.1 Labor Code, 1967, Section 6407). The employ, r also files a report, the Employer’s Report of Indus Extent of Exposure trial Injury. By definition, work injury includes oc­ cupational disease. The physicians’ reports of oc­ In the United States during 1970, approximately cupational disease are reviewed and subsequently 15,259,000 pounds of parathion were produced.2 published by the California Department of Public Technical grade material is formulated for insec­ Health in statistical report form. Agricultural wor­ ticidal application usually as 15% and 25% wetta- kers, exclusive of self-employed persons and un­ ble powders, dust concentrates (20% to 25%) and paid family labor, are covered by the California ready-to-use dry dust mixtures (1% to 10%), Workmen’s Compensation Law and thus come granules (2% to 25%), or emulsifiable concen­ under the reporting system. trates (2-8 pounds/gallon).3,4 Parathion may be en­ countered as a relatively pure substance in the In California during 1970, a total of 33,085 form of technical grade material, as a less-concen­ cases of occupationally-related diseases from ail trated component of various formulations, such as causes were reported.7 Of these, 207 cases of described above, or as dilute sprays and dusts dur­ systemic poisoning, or 0.63%, were due to OP ing field application. Even when parathion is con­ pesticides and 55 (27%) were attributed to tained in enclosed systems, potential exposures parathion.6 Sprayers, pickers, and truck and trac­ may occur from transfer of liquid, spillage, or from tor drivers were the occupational groups most af­ leaking equipment. Exposure may also occur dur­ fected. The report does not identify formulators as ing formulation, bagging operations, mixing , and a category of occupational exposure. Irrigator* and application or by accidental or intentional contact loaders were also frequently involved in poisoning with pesticidal preparations or incompletely emp­ by agricultural chemicals. The data from Califor­ tied containers of formulations. Such accidental nia essentially agree with those reported by exposures have been particularly frequent among Hatcher and Wiseman8 and Tabershaw and children less than 3 years old. Cooper,9 indicating that the greatest opportunities A number of occupations with potential expo­ for occupational exposure to parathion exist dur­ sure to parathion are listed in Table XVI-3. ing formulation and packaging operations, applica­ Besides parathion, there are a number of other tion equipment loading operations, and aerial and organophosphorus insecticides in use. In most ground applications. In addition to the 55 reported cases, the newer compounds have a lower mam­ cases of systemic parathion poisoning, 3 casf-s 13 complained of respiratory conditions, 3 of skin weeks and 4 months earlier, respectively. In conditions, 3 of eye conditions, and 31 un­ another episode, 10 workers experienced nausea, specified, for a total of 95 cases of occupational vomiting, and diarrhea while working in an orange illness due to formulations of parathion.6 Of these grove previously treated (5 weeks) with a mixture 95 cases, 77 were in agriculture, 8 in manufactur­ of parathion and . Quinby and Lem­ ing, 5 in transportation, communication, and utili­ mon13 reported parathion residue poisonings in ties, 4 occurred in state and local government California, Washington, and British Columbia. operations, and 1 in trade. Summaries of pertinent state peslicide regula­ The report of Hatcher and Wiseman8 is an ex­ tions are presented in Appendices VI and VII. ample of an effort to identify parathion poisoning NIOSH estimates that approximately 250,000 in a heavily agricultural area and the resulting workers (including field workers exposed to documentation of a large number of cases. In the residues) in the US are potentially exposed to lower Rio Grande Valley in Texas during 1968, parathion. 118 cases of OP were re­ Historical Reports ported. Ninety of these, or 78.2%, involved expo­ sure to parathion. Of the 118 cases of OP pesti­ According to Holmstedt14, the first indications cide poisoning, 97 were the result of dermal expo­ that OP compounds might be highly toxic ap­ sure, 20 occurred by the respiratory route, and peared during the early 1930’s when W'illy Lange only one case, a suicide attempt, was by ingestion. and Gerda von Krueger experienced symptoms These cases occurred during a year when while synthesizing dimethyl and diethyl parathion was used more extensively than before phosphorofluoridate. As early as 1934, Otto in an effort to overcome resistance by some of the of the I. G. Farbenindustrie appointed Gerhard major cotton pests. The authors concluded that Schrader to investigate synthetic insecticides. By the workmen occupationally exposed either did 1936, Schrader had turned his attention to or- not know or failed to appreciate the increased ganophosphorus compounds and, in 1937, he hazards associated with dermal exposure to patented the following general formula for contact parathion, and used only the precautions they had RIO 0(S) used in previous years when handling methyl parathion alone. The majority of acute or- ganophosphorus poisonings occurred in men em­ R20 X ployed in aerial application, almost 89.5% of those insecticides.14 Parathion (E605) and paraoxon affected being ground personnel who assisted in (E600) came out of Schrader’s laboratory in loading the planes with spray materials and fuel, 1944.14 Much of the information about Schrader’s row flagging, loading, unloading and opening work was disseminated outside Germany at the drums of undiluted material, or unloading and end of World War II when British Intelligence cleaning aircraft. No deaths resulted from the published information about parathion in 1947 in acute OP pesticide intoxications documented in the BIOS reports, as cited by Metcalf and March.15 this study. Limited production for agricultural use was begun Exposure of field workers to pesticide residues in this country in 1948.16 Cases of parathion on the foliage of crops has recently become a poisoning were reported soon thereafter. In 1949, matter of national concern (Federal Register Grob et al17 reported that a man employed as a 38:10715-17, May 1, 1973). During the years mixer of liquid parathion and clay powder had 1959-1963 in California, 369 cases of poisoning died after repeated exposures to the insecticide. attributed to parathion residues were reported10,11 The following year, Grob et al18 described the in field laborers involved in picking oranges, toxic effects of parathion in 32 men and 8 women grapefruit, olives, and peaches. At least 3 severe following accidental exposures. Since that time, episodes of OP insecticide residue poisoning in parathion has been responsible for many occupa­ orchard workers occurred in California during tional poisonings as documented, for example, by 1970.12 Each of the 3 orchards involved had been the California Department of Public Health 6'10 !2 treated about 2 weeks prior to crew entry with one during the ensuing years. or more of a combination of , Guthion, Effects on Humans Delnav, or parathion. Fourteen of 35 crew mem­ bers were hospitalized after picking oranges in a Table III-3 summarizes the experimental and grove treated with parathion and Delnav nearly 5 epidemiologic effects noted in humans exposed to 14 TABLE III-l SIGNS AND SYMPTOMS ASSOCIATED WITH ACUTE AND SUBACUTE EXPOSURES TO PARATHION Effector Organ Sign or Symptom I. MUSCARINIC manifestations (a) Gastrointestinal Anorexia; nausea; vomiting; abdominal cramps; diarrhea; tenesmus; involuntary de­ fecation; eructation; ‘'heartburn”; substernal pressure (b) Sweat glands Increased sweating (c) Salivary glands Increased salivation (d) Lacrimal (tear) glands Increased lacrimation (e) Cardiovascular system Bradycardia, fall in blood pressure (f) Bronchial tree Tightness in chest; wheezing suggestive of broncho-constriction; dyspnea; cough; in­ creased bronchial secretion; pulmonary edema (g) Pupils Pinpoint () and nonreactive (h) Ciliary body Blurring of vision (i) Bladder Increased urinary frequency; involuntary urination 2. NICOTINIC manifestations (a) Striated muscle Muscular twitching; fasciculation; cramping; weakness (including muscles of respiration) (b) Sympathetic ganglia Pallor; tachycardia; elevation of blood pres­ and adrenals sure 3. CENTRAL NERVOUS SYSTEM manifestations Uneasiness; restlessness; anxiety; tremulous­ ness; tension; apathy; giddiness; withdrawal and depression; headache; sensation of “floating”; insomnia with excessive dreaming (nightmares); ataxia; slurred, slow speech with repetition; drowsiness; difficulty in con­ centrating; confusion; emotional la'bility; coma with absence of reflexes; Cheyne- Stokes respirations; convulsions; hyperpy­ rexia; depression of respiratory and circu­ latory centers (with dyspnea and fall in blood pressure) Derived from 18,52 parathion. Evaluative or qualifying information on enzyme which is present in serum. Of the each study is included in the more complete esters, the only one with demonstrated physiologic description of the study as reported in the text. importance to man is acetylcholine, the substance which mediates the transmission of nerve impulses (a) Physiology to the heart and to other parasympathetically in­ The actions of such organophosphorus com­ nervated structures, including the iris, the salivary pounds as parathion depend upon the enzymes glands, the stomach and small intestine, the urina­ which they inhibit and the physiologic effects of ry bladder, the bronchial glands, and a few post­ such enzyme inhibition. These enzymes catalyze ganglionic sympathetic fibers, such as those to the the hydrolysis of acetylcholine and other cholineeccrine sweat glands.1 Acetylcholine has been esters. In 1932, Stedman and his coworkers19 sug­ shown to have a transmitter function also in 3 ad­ gested the term “choline-esterase” (sic) for the ditional classes of nerves: the preganglionic fibers 15 of both the sympathetic and parasympathetic Aging of the phosphorylated enzyme has been at­ systems, motor nerves to skeletal muscles, and cer­ tributed to a mono dealkylation of the phosphoryl tain neurons within the central nervous system.1 or phosphonyl moiety, resulting in a change in the In man, there are two principal types of enzymes electronic charge of the phosphorus atom such which hydrolyze choline esters: (1) that it can no longer be approached by the acetylcholinesterase (AChE), or true hydroxyl ion of water.28 cholinesterase, and (2) butyrocholinesterase Regeneration of non-aged phosphorylated AChE (BuChE), frequently called plasma cholinesterase, is accelerated by nucleophilic reactivators, such as serum cholinesterase, or pseudocholinesterase.1 choline, pyridine, hydroxylamine, hydroxamic Acetylcholinesterase occurs in neurons, at the neu­ acids, and oximes.27 In 1951, Wilson28 reported romuscular junction, in erythrocytes, and in cer­ that choline and hydroxylamine reactivated diethyl tain other tissues.1 Practically all of the phar­ phosphorylated-AChE considerably faster than macologic effects of the anti-cholinesterase agents, water alone. Childs et al29 found that the oximes including those of parathion, are due to the inhibi­ were generally superior to the hydroxamic acids in tion of AChE, with the subsequent accumulation reactivating OP-inhibited ChE. Wilson30 32 synthes­ of endogenous acetylcholine.1 ized and tested several monoquaternary pyridine Throughout the remainder of the document, the aldoximes. Subsequently,33 pyridin“ '’-aldoxime (2- designation ChE is used interchangeably with the PAM; ) methochloride was found to be word cholinesterase. In all instances where ChE highly effective in the reactivation of non-aged, in­ appears, it will be preceded or followed by either hibited RBC and neuroeffector ChF’s RBC, designating the erythrocyte enzyme, or (b) Absorption plasma (or both), or blood, or whole blood in Parathion is absorbed through the gastroin­ order ¡o clearly indicate which cholinesterase(s) testinal tract,34'3” the respiratory tract,37,38 and the is/are being referred to. In a similar vein, the skin, the mucous membranes, and the eyes.11,16,39'41 designation RBC is used interchangeably with Gleason et al42 pointed out that the response erythrocyte. sequence and the interval between exposure and BuChE is present in various types of glial or response are partly dependent upon the portal of satellite cells of the central and peripheral nervous entry. Respiratory tract symptoms usually appear systems, as well as in the plasma, liver, and other first during a respiratory exposure 43 whereas the organs.1 It has no known physiologic function; in­presenting symptoms are more likely to be gas­ hibition of the plasma enzyme at most sites trointestinal following ingestion.18 As shown by ex­ produces no apparent functional derangement.1 perimental results,5 parathion (equivalent dose Lehmann and Liddell20 speculated that the plasma basis) is less toxic by the dermal route than by in­ ChE may hydrolyze those cholinesters which in­gestion. Holmstedt43 speculated that this may be hibit acetylcholinesterase. These include propio- due to enzymes in the skin causing hydrolysis of nylcholine and butyrylcholine, which can be parathion, much in the same way that paraoxon is formed in vitro by enzyme systems responsible fordetoxified partially during passage through the skin the synthesis of acetylcholine and may be in man, rabbit, and cat as reported by Fredriksson produced also by bacterial action in the gut. There et al.44 However, the latter investigators44 were are a number of atypical plasma ChE’s, discovered unable to show that significant of through an investigation of abnormal responses to parathion takes place in dermal tissue; it was ab­ the muscle relaxant, succinylcholine, which appear sorbed in essentially unchanged form. Passage of to be genetically controlled variants with differing parathion through human skin was shown to be abilities to hydrolyze acetylcholine and related relatively slow (0.001 /u,g/rnin/sq cm in vitro), 45 compounds.20,21 and consequently a dermal exposure may result in Parathion has only a slight direct inhibitory ac­ a substantial as well as a prolonged period of ab­ tion on plasma and RBC ChE’s but its active sorption. However, although dermal absorption of metabolite, paraoxon, is a potent inhibitor of these parathion is a relatively slow process, the com­ enzymes.22'25 The resultant phosphorylated enzyme pound is neither irritant nor caustic in nature39 and is stable, so that hydrolysis leading to reactivation therefore provides no warning to the individual of the enzyme occurs slowly. Hydrolysis is limited,that his skin has been contaminated with however, by another spontaneous reaction, aging, parathion. Thus, dermal absorption leading to which leads to a stable phosphorylated RBC ChE, signs and symptoms of poisoning may occur refractory to spontaneous or induced hydrolysis.1without any awareness on the part of the exposed 16 individual. In actuality, dermal absorption has metabolic conversion was necessary. Incubation of been shown to be a potentially greater hazard than parathion with liver slices did produce the active respiratory absorption for parathion applicators.46 inhibitor, O.G-diethyl-O-p-nitrophenyl phosphate In controlled studies, Durham et al46 evaluated (paraoxon).24,48 Kubistova24 demonstrated in vitro the comparative dermal and respiratory exposure that enzymatic oxidation takes place also in the of workers subjected to the mist from an airblast gut, lungs, kidneys, and suprarenal glands. Gar- spray machine during parathion application in docki and Ha 2:leton49 found PNP to be the major orchards. Three test subjects were about equally nonphosphorus-containing end product of exposed to the parathion spray drift by transport parathion metabolism in dogs, although traces of in a vehicle following the spray machine at such a p-aminophenol were also found. PNP has been distance that the spray mist that came into contact shown to be a major urinary metabolite of with their bodies had to be fine enough to remain parathion in man.50,51 suspended in the air for a comparatively long (d) Acute Effects period. The fine mist encountered approximated The acute effects of parathion are due largely to that to which the operator of the spray rig was ex­ its ability to inhibit ChE’s throughout the body.1 posed. One individual was completely covered As indicated in the preceding section, inhibition of with rubber and plastic clothing to prevent skin these enzymes in animals (including man) leads to contamination. He wore no respirator and thus the accumulation of endogenously produced had a respiratory exposure. A second worker wore acetylcholine, with the resultant signs and symp­ a respirator and breathed only noncontaminated toms in man set forth in Table III-1.18,52 This table air; however, he wore ordinary clothing and thus classifies man’s response according to muscarinic, his exposure was dermal only. The third person nicotinic, and central nervous system (CNS) had neither respiratory nor dermal protection, responses. Muscarinic effects refer to the action of other than ordinary clothing. All three subjects parathion on autonomic effector cells of the eyes, wore absorbent pads to provide a measure of their heart, lungs, stomach, blood vessels, and other or­ surface exposures to airborne parathion. Analysis gans.1 Varying proportions of muscarinic receptors of the absorption pads worn by the subjects con­ are also present on autonomic ganglion cells and firmed that all were subjected to parathion of the on certain cortical and subcortical neurons.1 The same order of magnitude (approximately 0.03 nicotinic actions of parathion refer to its effects mg/sq in. for the 2 “protected” workers). How­ (initial stimulation in high doses leading to sub­ ever, total p- (PNP) excretion for the sequent blockade) on autonomic ganglion cells man wearing the rubber and plastic clothing and the neuromuscular junction, actions compara­ (respiratory exposure only) was 0.088 mg; for theble to those of nicotine.1 Such a classification individual using the pure air supply (dermal expo­ scheme is of some use in the rationale for treat­ sure only), 0.666 mg; and for the man using no ment and diagnosis, since , in the dosages special protective equipment (both respiratory and •normally used to treat parathion poisoning, blocks dermal exposure), 0.433 mg. Since parathion has the muscarinic and CNS effects, but not the been shown by Fredriksson44 not to be hydrolyzed nicotinic effects.1 or transformed into paraoxon by the skin of man, The frequently observed delay in onset of symp­ the use of urinary PNP excretion appears to be a toms of poisoning after exposure to parathion is valid procedure for the relative measurement of attributed to the requirement that parathion be parathion absorption. The results show that dermal metabolized in the body to paraoxon.25 However, absorption exceeded that by the respiratory route commercial preparations of parathion have been by several times, clearly indicating the potential reported22 to contain small amounts of the S-ethyl danger from dermal exposure to parathion. isomer which can produce localized effects at the Dermal absorption of parathion may be in­ site of contact. The sequence of symptoms de­ creased by the solvent used. Absorption of pends on the route of entry of parathion prepara­ parathion from the skin of the forearm was ap­ tions into the body and on their composition.16,43 proximately tripled by its application in the known Appearance (signs of) of poisoning with dermal irritant xylol above that measured when it was ap­ exposure to parathion is delayed, the onset being plied in acetone.47 insidious after a latent period of one or more (c) Metabolism hours.»,17.52 Delayed absorption of parathion from The observation by Diggle and Gage22 that material deposited on the skin or clothing can also parathion in a pure state was a poor inhibitor of occur over a period of several weeks or months. rat brain ChE in vitro led to the conclusion that Kazen et al53 found parathion on the hands of one 17 man 2 months after his last known contact with became ill, exhibiting signs and symptoms of or- the insecticide. The authors found 38.8/ng of ganophosphorus insecticide poisoning. No indica­ parathion on the hands of another pesticide ap­ tion of the dosage received was provided. Because plicator 31 days after spraying. The delay of oc­of the extremely low vapor pressures of the pesti­ currence of systemic effects following dermal ex­ cides,54'5” the time of entry into the treated field, posure to parathion may be attributable to two the dew-laden nature of the foliage, and the neces­ factors: sity of worker-plant surface contact, these acute (1) the slow rate of absorption through the poisoning cases were probably due primarily to skin45; dermal absorption of the insecticides. (2) contaminating paraoxon may be par­ (e) Chronic Effects tially detoxified during passage through the skin.44 Another hazard to workers relates to repeated Although the acute for man is unk­ exposures to small quantities of parathion, such nown, the results of animal experiments, as that during a period of time the cumulative effect presented in the Animal Toxicity section, demon­ on tissue AChE may lead to toxic effects. strate the extreme toxicity of parathion to mam­ Parathion itself, or its metabolic oxidation product mals. paraoxon, does not cumulate to a significant Many occupational accidents involving degree in the body as evidenced by urinary PNP parathion have occurred through the dermal excretion.50-51 However, the effects of repeated route.6’8'9,18 Tabershaw and Cooper9 presented the small doses do become cumulative if replacement case histories of several workers who developed of AChE at its sites in tissues does not keep pace signs and symptoms (eg, nausea, vomiting, weak­ with the extent of inhibition of the enzyme.57 ness, blurring of vision) of OP insecticide poison­ In an effort to determine, on the basis of daily ing while picking citrus fruits in orchards previ­ ingestion, the amount of parathion capable of ously sprayed with parathion. In some cases, the producing minimal toxicity, Rider et al34 exposed insecticide had been applied as long as 25 days be­ groups of five human volunteers to daily oral doses fore worker entry, thus implicating the dermal of either 3.0 mg, 4.5 mg, 6.0 mg, or 7.5 mg for route of exposure. However, it is difficult to rule periods approximating 30 consecutive days. Each out completely the possibility of concurrentgroup contained 2 control subjects who received respiratory and oral intake. only corn oil. The groups exposed to 3.0 mg and Hartwell et al37 exposed human volunteers to 4.5 mg showed no changes from baseline ChE vapor or particulates of parathion generated by levels. The group at the 6.0-mg level sustained a either heating parathion dust or technical grade slight (unspecified) depression of plasma ChE. The parathion or by spraying technical grade parathion effects of 7.5 mg/day were such that by day 16 the into a chamber. No air sampling was performed. plasma ChE levels of 2 subjects had decreased to Urinary PNP excretion was determined from im­ 50% and 52% of pretest levels, respectively, at mediately prior to exposure until 40 hours after which point administration of parathion was exposure. Both RBC and plasma ChE activities discontinued; by day 23, the plasma ChE activity were determined. Neither the 2% dust heated to of another test subject had dropped to 54% of his 82°F and 120°F nor the technical grade heated to pretest level, at which point his participation in the 82°F and 105°F produced depressions exceeding study was ended. The remaining 2 subjects con­ 30% of preexposure values in either RBC or tinued throughout the 35-day test period. Their plasma ChE activity levels. Also, urinary PNP lowest plasma ChE values were 86% and 78% of excretion was minimal in these exposures. How­ pretest values, respectively. The lowest RBC ChE ever, a subject exposed to parathion accidentally activity levels obtained during the study for the 3 heated to 150°F experienced signs of poisoning, a subjects to whom the administration of parathion decline in RBC and plasma ChE activities to 2% was discontinued were 63%, 78%, and 86%> of and 12% of normal, respectively, and the excretion pretest levels, respectively. The 2 subjects who of large quantities of PNP (approximately 6 mg in completed the test period experienced no signifi­ 7 days). cant reduction of RBC ChE activity. The plasma In one Texas episode,8 a group of field workers ChE was affected to a greater extent than the RBC entered a cotton field containing plants about 3V£ ChE. The investigators considered that average feet tall approximately 12 hours after an aerial ap­ depressions of the ChE activities in blood of 20- plication of a mixture containing parathion and 25% below control values were significant. The methyl parathion. After working around the dew­ results demonstrated that the daily ingestion of 7.5 laden plants for 2V4-3 hours, 23 of the workers mg of parathion by man during 35 days led to a significant reduction in blood ChE activities and sprayers, 27% for those reporting symptoms, and thus constitutes an unsafe ingestion level. Because 17% for those reporting no symptoms, the dif­ of the incompleteness of the data on the 6.0-mg ference betweeen the depressions in the sympto­ daily dose, NIOSH concludes that only the 4.5-mg matic and the symptom-free groups being insignifi­ daily dose can be regarded as the maximum safe cant. The results for plasma ChE, however, dose for parathion tested. presented a different picture. In the group report­ In another study, Edson35 found that an oral ing symptoms, the plasma ChE activity was 20% dose of 7.2 mg parathion/day, 5 days/week, for 6 lower than in the group reporting no symptoms. weeks produced a 33% decrease in whole blood Using the average control value for all subjects ChE activity (16% and 37% for RBC and plasma determined approximately 3 months following ex­ ChE, respectively) in 4 adult female volunteers. posure, the plasma enzyme activities in the groups This corresponded to a daily oral intake of 0.078 reporting symptoms and no symptoms were mg/kg. No significant effects on the activities of depressed 22% and 3.5%, respectively. The ChE’s in blood were observed as a result of the authors reported that approximately one-half the daily oral ingestion by groups of 4 subjects of exposed workers reported no symptoms of ill- either sex of 0.6, 1.2, 2.4, or 4.8 mg of parathion health. The symptoms mentioned by the remaining for periods ranging from 25 to 70 days. The results half included nausea, headaches, and other non­ showed that a safe no-effect daily oral dose of specific symptoms on one or more occasions, with parathion in humans was smaller than 0.078 mg/kg a few cases of confining illness of short duration. and greater than 0.058 mg/kg. Two major points must be emphasized concerning In 1958, Rider et al36 published the results of these results. Firstly, the exposure to parathion similar studies which demonstrated that the daily was intermittent allowing time for partial return of ingestion of 0.05 mg/kg/day of parathion by hu­ blood ChE activity. Regeneration and replacement mans produced no significant decrease in plasma of enzyme activity between exposures undoubtedly or RBC ChE activities and thus constituted a safe account for the fact that depressions were not ingestion level. more severe in light of the magnitude of the air­ Kay et al58 studied the effects of exposure to borne exposure to parathion. Secondly, little parathion sprays on the ChE activities of the blood emphasis can be placed on the association of Quebec apple-growers. Airborne parathion con­ between the occurrence of the reported non­ centrations were determined, using impingers and specific symptoms and the levels of depression of fritted glass bubblers in series, both during and RBC and plasma ChE activities due to the inability after spraying of 15% wettable powder (W/w) in to calculate incidence rates from the data. Hayes concentrations of 0.75 to 1.5 lb/100 gal of water et al59 found that part-time OP insecticide applica­ and dispersed at the rate of 300-400 gallons/acre. tors experienced nausea no more frequently than The orchards were sprayed from early Maydid controls (5%> 4%) and headache less often through June. Measurements were made in 4 (5% vs 19%). orchards during approximately 4 weeks, beginning CNS effects of chronic exposure to parathion on May 28th. Both hand-held and mechanical and similar compounds have been reported.8063 sprayers were used. Air samples taken from the Gershon and Shaw®' reported the effects on the breathing zones of the operators ranged from 2 mg CNS of 16 workers “chronically exposed” to OP to 15 mg/m3 of air, reflecting downwind versus up­ insecticides, including parathion. Of the 16 cases wind (with heavy “blow back” and resultant high mentioned, only 4 case reports were presented by exposure) spraying. The sprayers were exposed for the authors. In one case involving parathion expo­ approximately 2 days at 10-day intervals during a sure, the individual exhibited severe depression, 2-month period. Personal protective measures, nightmares, impairment of concentration and such as coveralls, rubber boots, caps, and fabric memory, headache, and irritability. A mitts, were used by some workers. Respirators schizophrenic reaction including auditory hallu­ were indifferently used by approximately one-third cinations was observed in a second parathion-ex- of the group. Both RBC and plasma ChE activities posed worker. Nausea and vomiting, muscle were determined by a modified Michel technique. cramps, and dizziness also occurred in both. Blood samples were taken thrice during the spray­ Parathion exposure levels were not reported. In ing period and singly during the first and fourth both of these cases, after cessation of exposure for months following the termination of exposure, for several months, these effects disappeared and the use as control values. Depression of RBC ChE ac­ patients were feeling well. However, it must be tivity at the end of exposure averaged 2 1 % for all emphasized that both of these cases involved expo­ sure to parathion and other ChE-inhibiting insecti­ changes were present in test subjects exposed to a cides. Other investigators64"*8 have presented variety of pesticides even when there was no mea­ reasons, and data, to doubt the conclusion of surable decrease in blood ChE activity or adverse Gershon and Shaw that the psychoses studied by changes as indicated by routine physical examina­ them were consequences of exposure to OP com­ tion.67 EMG may prove to be a sensitive method to pounds. provide an early warning of exposure to parathion Mixed exposures to pesticides are common in as well as other OP pesticides. agriculture, a situation which complicates distin­ Some attention has been given to the possibility guishing definite, specific biologic responses to ex­ that parathion may produce the type of paralysis posures to individual compounds. In a similar vein, reported as a consequence of exposure to TOCP Davignon et al62 reported on the chronic effects of (tri-o-cresyl phosphate), DFP, and (N,N’- insecticides, including parathion, in man. Signs of diisopropylphosphorodiamidic fluoride).69 Bidstrup possible chronic intoxication due to insecticides et al89 stated that according to their observations were sought among 441 apple-growers. Because the noted effects of mipafox closely resembled the growers had been exposed at various times to those of “ginger” paralysis caused by the drinking undetermined quantities of malathion, parathion, of extract of Jamaica ginger contaminated with azinphosmethyl, , DDT, , TOCP. Although a case report70 of suspected , and other insecticides, the observed in­ parathion-produced delayed paralysis was creased incidences of leukopenia and neurologic published in 1950, it does not clearly implicate abnormalities, including weakening or loss of parathion as a cause of permanent neuromuscular reflexes and disturbances in equilibrium, could not damage. Petry70 reported that delayed polyneuritis be attributed securely to parathion. developed in a worker who had sprayed a dilute Durham et al,63 in a study of 53 persons exposed solution of parathion within closed hothouses dur­ to OP insecticides to determine whether or not ing a 4-week period. Subsequent to each of 10-12 mental effects may precede or take place in the applications, the man experienced nausea, an urge complete absence of other more disabling signs or to vomit, and anorexia. Approximately 50 days fol­ symptoms of OP poisoning, found no mental ef­lowing the last spraying, during which time he fects at levels where other clinical symptoms were became ill with severe gastritis and was hospital­ not also present. In one case, an aircraft loader ized, he noticed a feeling of tingling, numbness, was exposed to undetermined amounts of and weakness in his legs which ultimately parathion, tetraethylpyrophosphate, , and progressed to a permanent paralysis of the at various times for approximately 6 peroneus muscles. However, this appears to be an weeks. Sometime after the third week, he isolated human case and delayed adverse neu­ frequently became dizzy, noticed a slowing of his romuscular effects, such as paralysis, have not driving reactions, and complained of a loss of been shown to be a usual effect of parathion expo­ sense of timing. Prior to the appearance of these sure, either acute or chronic. effects, his blood ChE activity was shown to be The question of variability of individual suscepti­ severely depressed (RBC and plasma ChE activi­ bility to parathion poisoning has not been studied ties were reported as 0.10 and 0.27ApH/hr, fully. Experimental data71 indicate strongly that respectively). In addition, other more common both plasma and RBC ChE may serve as signs of poisoning, such as muscular twitching “buffers”, protecting functional AChE from inhibi­ (eyelids), nausea, and anorexia, had preceded the tion by DFP. Although few in number, there are in mental effects. Mental confusion and hallucina­ the general population people who have a genetic tions occurred in another worker after 6 weeks of plasma ChE variant20,21 which, in the heterozygous spraying trees with parathion using a hand-held or abnormal homozygous state, may serve less well sprayer. Headache, nausea, and paresthesia as a buffer than the normal enzyme. However, preceded the mental effects, which included con­ Tabershaw and Cooper9 in studying the case histo­ fusion, hallucinations, and amnesia. None of the ries of 108 individuals poisoned by parathion or so-called mental effects persisted after termination other OP pesticides found that 5 persons with the of exposure. heterozygous variant were not more severely There is an indication that electromyography poisoned than those with the normal enzyme. Peo­ (EMG) can detect changes in neuromuscular func­ ple heterozygous for this variant occur in the nor­ tion in parathion-exposed workers who show no mal population to the extent of 37/1,000, while evident effect from their exposure.67,68 These the frequency of the atypical homozygote has been 20 estimated at 1/2820 of the population.21 Depres­ The remaining 18 categories accounted for only sion of liver function by hepatotoxic materials can 39% of the reported occupational illnesses due to result in lower plasma ChE.72 Low plasma levels pesticides. These data indicate the more hazardous are also seen in malnutrition, chronic debilitating occupations in the pesticide “industry.” This re­ disease, acute infectious disease, and anemia.72'74 port by Maddy and Peoples78 encompasses all Drugs which have been shown to decrease plasma pesticides and is not specific to parathion. ChE activity include and related In 1950, Brown and Bush79 reported a study of compounds,75 Vitamin K,72 folic acid,72 workers in an industrial plant manufacturing both tetraethylammonium chloride,72 quinine and a concentrated parathion and a dust formulation number of other antimalarial drugs,78 morphine, containing parathion. Air samples were taken at 8 codeine, and related analgesics.77 locations throughout the plant; 2 samples were The rate of return of plasma ChE activity to its taken in the breathing zone of workers and the normal value in man following depression by others were general atmosphere samples. Blood parathion has been shown to be approximately 3- ChE (RBC and plasma) activity measurements 4%/day.18 In a study of 18 subjects whose plasma were performed on 12 workers engaged in various and RBC ChE had been depressed by parathion, jobs during a 6-month period. The concentration the plasma enzyme increased at an average rate of of parathion in the air varied from 0.1 to 0.8 approximately 9% of normal activity during each mg/m3, with a mean exposure concentration of of the first 3 days. This rate decreased to 5% by about 0.2-0.3 mg/m3. Details of times of sampling the fourth day and to 3% by the tenth day, after were not given. A greater than 30% depression in which it remained steady. During the first 3 -days either or both plasma and RBC ChE activity was following depression, the RBC enzyme activity in­observed in 5 exposed workers from whom succes­ creased at an average rate of approximately 3.3% sive blood samples were taken during a 6-month of normal activity. This rate diminished to between production period. The authors reported that the 1-2%/day by the fourth day and remained relative­ plasma enzyme activity was depressed more than ly constant thereafter (RBC ChE activity increased that of the RBC’s. However, based on blood ChE about 90% in 70 days). activity levels measured 5 months following the cessation of parathion manufacture (ie, using these values as control levels) RBC enzyme activity was depressed to a greater extent than that of the Epidemiologic Studies plasma in these 5 workers during the exposure Epidemiologic studies of parathion-exposed phase. Since the data do not allow for correlation worker populations have been directed at identify­ of the ChE activity of whole blood with airborne ing the types of workers at greatest risk, the en­ concentrations of parathion on a precise basis, the vironmental conditions associated most frequently only reasonable conclusion from the results is that with poisoning, and the biologic results of pro­ continuous exposure to an airborne concentration longed exposure in an effort to determine whether of parathion above 0.2 mg/m3 can result in a or not chronic effects occur. One study50 involving reduction in blood ChE activity. The data do not exposure to parathion indicated that mixing-plant identify a safe exposure level. No mention was personnel, commercial ground applicators, aircraft made of percutaneous parathion absorption. application workers, and orchard workers were the Arterberry and associates50 used measurements groups at greatest risk, while field men and of both blood ChE and urinary excretion of PNP warehousemen were at lesser risk. to identify occupations with high exposures to In 1976, Maddy and Peoples78 reported on occu­ parathion. These biologic indicators were used to pational illnesses due to exposure to pesticides or determine the extent of exposure to parathion bv their residues in California during 1973-75. Under workers performing a variety of jobs. The study the category of systemic illness the 5 occupationsgroups included mixing plant personnel, commer­ experiencing the greatest problems in those years cial ground applicators, part-time ground applica­ were: (1) ground applicators—96 cases; (2) mixers tors, aircraft application workers, workers in and/or loaders—74 cases; (3) indoor workers ex­ orchards (especially thinners), field men, posed to pesticides—50 cases; (4) formulation warehousemen, miscellaneous workers, and re­ plant workers—41 cases; and (5) firemen exposed sidents living near orchards. Only the mixing plant to pesticide fires—37 cases. Field workers exposed workers showed a definite decrease in ChE activity to pesticide residues was the number 6 category, within the blood, limited to ChE activity in the with 28 reported systemic illnesses. RBC’s (36% decline). PNP excretion was greatest 21 in the commercial ground applicator group and of 4 peaches/day with parathion residue levels of decreased in the following order: part-time ground 125/xg/peach; inhalation of 350/Ag parathion/day applicators, mixing plant personnel, aircraft appli­ based on the highest breathing zone concentration cation workers, and workers in orchards found in the study, 35/n.g/m3, and a breathing rate (especially thinners). The PNP excretion of the of 10 m3/day; and a calculated daily dermal expo­ field men and warehousemen was less than half sure of around 3,000f/.g based on multiplying the that of the orchard workers. The study demon­ results of skin-rinse analyses by skin surface areas. strated that mixing plant personnel, ground ap­ They concluded that insufficient parathion was plicators (commercial and part-time), aircraft ap­ present on the surface of trees to produce illness plication workers, and orchard workers were the in the orchard workers, and that some unmea­ groups at greatest risk, while field men and sured, yet active anticholinesterase agent, probably warehousemen were at lesser risk. paraoxon, also must have been present. Supporting Quinby and Lemmon1J called attention to the this conclusion was the fact that one sample of residue of parathion on the foliage of trees and leaves analyzed for paraoxon indicated the vines as a source of poisoning. They investigated presence of 3.0 ppm paraoxon and 2.8 ppm 1 1 episodes of group poisoning involving more parathion. than 70 persons from pesticide residues on the sur­ faces of plants. Illness was confirmed by low blood Animal Toxicity ChE values and relief of symptoms by atropine. Table III-4 summarizes animal data on the tox­ One episode involving 16 cases occurred 33 days icity of parathion by various routes of administra­ after spraying. Two days after the outbreak of tion. Evaluative or qualifying information on each poisoning, residue analysis showed that the leaves study is included in the more complete description contained 8 ppm of parathion. of the study as reported in the text. Milby and coworkers11 studied an outbreak of (a) Acute Effects parathion poisoning in 186 peach orchard workers. LD50 data for various species are presented in After elimination of the spraying-picking interval Table III-2. by matching workers in the various orchards on Because there is a significant sex difference in the basis of similar mean intervals, illness response to parathion in rats,5’80 separate values developed in orchards that received an average of are provided for males and females. Such marked 7.14 pounds/acre of parathion but did not develop sex differences were not seen in other species.5'8UiH1 in those that received an average of 4.99 (b) Subacute Studies pounds/acre. However, Milby et al,11 utilizing A cumulative toxic action of parathion in female breathing zone air samples and skin washes to rats was shown by DuBois et al.80 After daily in- measure the potential inhalation and dermal expo­ traperitoneal doses of 3 mg/kg of parathion, none sures, calculated that the maximal daily dose of of 15 test animals survived more than five doses of parathion with which a worker could have come the insecticide. Daily intraperitoneal doses of 1 into contact was not in excess of 4 mg. This value and 2 mg/kg of parathion for 10 days resulted in was derived in the following manner: the ingestion 46% and 87% mortality, respectively. None of 5 TABLE III-2

LD50 VALUES OF PARATHION (mg/kg) IV [80] IP [80] Oral [5] Dermal [5] Rats Male — 7 13 21 Female — 4 3.6 6.8 Mice — 9-10 — — Cats 3-5 — — — Dogs 12-20 — — —

22 TABLE III-3 EFFECTS ON HUMANS FROM PARATHION EXPOSURE Number of Route(s) of Subjects Exposure Concentration Exposure Exposed and Duration Effects Reference Respiratory 1 2% parathion dust (PD) heated No signs or symptoms of parathion [37] to 82CF for 30 min. on day 1; poisoning observed. At 82°F, lowest 2% PD heated to 120°F for 30 RBC ChE activity was 80% of pre­ min. on days 2 and 3; 1 ml tech exposure value. Insignificant plasma parathion (TP) heated to 82°F ChE inhibition. No depression of for 30 min. on day 6; 1 ml TP ChE activities at 105°F. At 120“F, heated to 105°F for 30 min. on lowest RBC and plasma blood ChE day 8; 1 ml TP heated to 120 F activities were 63% and 66% of pre­ for 30 min. on days 10-12 (in exposure values, respectively. all exposures breathing zone concentrations of parathion were unknown). First 3 exposures listed for above No signs or symptoms of parathion [37] subject. poisoning observed. At 82°F. low'est RBC ChE activity was 85% of pre­ exposure value; insignificant inhibi­ tion of plasma ChE. At 120°F, low­ est RBC and plasma ChE activities were 78% and 89% of preexposure values, respectively. 1 ml TP heated to 105-115°F No clinical signs of poisoning either [37] for 30 min. on 4 consecutive during or following the first 4 ex­ days; 5 ml TP heated to 150°F posures; after 10 min. at 150°F for 10 min. on 5th day. (accidental), the subject developed unspecified signs of parathion pois­ oning. Dermal and 1 female A “few days” (unspecified) ex­ Signs and symptoms, including head- [58] respiratory and 32 male posure during each 10-day spray­ aches and nausea, were reported by adults ( 39 ing interval over a 2-month pe­ about one-half of the exposed group. nonexposed riod to airborne concentrations Average RBC and plasma ChE activ­ controls) of parathion ranging from 2 to ities were 21 % and 13% lower at the 15 mg/cu m (during orchard- end of the spray period than they spraying operations). were about 4 months later. The plasma ChE activity in the group with symptoms was 20% low'er than in the symptom-free group. I male Exposed to a 1:10,000 spray of Subject experienced nausea and vom- [70] parathion 10-12 times during a iting several hours after each spray­ 1-month period (during hot­ ing: was hospitalized about 2 months house spraying operations). later with gastritis. Ultimately de­ veloped polyneuritis in the legs. 12. plus Intermittent exposures to para­ No signs or symptoms of parathion [79] I listed thion at concentrations of 0.1- poisoning. Apparently significant de­ as being 0.8 mg/cu m. pressions of both RBC and plasma "not exposed" ChE activities in some employees. I 15* Varied, but unknown (no air 36% decline (mean) in the RBC [50] sampling performed). ChE activity in the blood of mixing- plant employees. No significant de­ cline in the plasma ChE activity of either mixing-plant employees or any of the other exposure groups. 23 TABLE III-3 (c o n t i n u e d ) Number of Route(s) of Subjects Exposure Concentration Exposure Exposed and Duration Effects Reference Dermal Not stated Entered the field about 12 hours 23 workers exhibited signs/'symp- [8] ( cotton-field after the aerial application of a toms of OP poisoning; 13 required workers) mixture of methyl parathion and hospitalization while 10 were suc­ parathion; worked for 2.5-3 cessfully treated as outpatients. hours. Oral 5. plus 2 Subjects orally ingested capsules No significant inhibition of RBC or [34] nonexposed containing 3.0, 4.5, 6.0, or 7.5 plasma ChE activities at 3.0 and 4.5 controls mg parathion/day for approx­ mg/day doses. “Slight" (unstated % ) imately 30 days. Controls re­ inhibition of plasma ChE at the 6.0 ceived corn oil only. mg parathion- day dose. Plasma ChE activities w'ere inhibited to 50% and 52% of pretest levels in 2 of 5 sub­ jects receiving 7.5 mg parathion/day for 16 days. After 23 daily doses of 7.5 mg parathion, a third subject's plasma ChE activity was 54% of his normal value. Effects were less on the RBC activities of the exposed subjects. No signs/svmptoms of poi­ soning were reported by the authors. 4 (males Subjects orally ingested 0.6, 1.2, Effects on blood ChE activities were [35] and females) 2.4, 4.8, or 7.2 mg parathion/ observed only at the 7.2 mg/day day, 5 days/week for 25-70 days dose: whole blood ChE activity de­ (4 adult females received the clined to 67% of control activity 7.2 mg/day doses). after 6 weeks (RBC and plasma ChE activities at this time w'ere 84% and 63% of control activities, respec­ tively). No signs/symptoms of para­ thion poisoning were reported by the author. 8 (4 males Subjects orally ingested 4 dose- No effects on RBC or plasma ChE at [36] and 4 females) levels of parathion for 12 weeks any dose level. No signs; symptoms at 3 weeks/dose-level. The suc­ of parathion poisoning were reported cessive doses (capsules contain­ by the authors. ing parathion in corn oil) were 0.003, 0.010, 0.025, and 0.050 mg/kg. 2 subjects received corn oil only. * 35 mixing-plant personnel, 2 commercial ground applicators, 44 part-time ground applicators, 4 aircraft application workers, 7 orchard workers, 3 fieldmen, warehousemen, and miscellaneous workers, and 20 residents near orchards.

24 TABLE III-4 RESULTS OF ANIMAL TOXICITY STUDIES OF PARATHION Route of Administration Species Number Results Reference Intraperitoneal injection: Rats [80] a) 3 mg/kg/day (female) a) 15 a) None survived more than 5 doses b) 2 mg/kg/day b) 15 b) 87% mortality after 10 days c) 1 mg/kg/day c) 24 c) 46% mortality after 10 days d) 0.5 mg/kg/day d) 5 d) No deaths after 20 days of dosing Oral: 1 mg/kg for 9 days, Rats Unreported No alteration of conditioned behavior [82] followed by 2 mg/ kg for (sex 2 days, followed by unstated) 5 mg/kg for 4 days Oral: Mice 20/group for [83] a) 12 mg/kg behavioral a) Impaired performance on a passive- tests; 6/group avoidance task; killed 40% of test for ChE determinations b) 8 mg/kg b) Impaired performance; killed 19% of test mice c) 6 mg/kg c) Impaired performance; killed 10% of test mice d) 4 mg/kg d) Impaired performance Subcutaneous injection: No effect on passive-avoidance learning: [83] 1-4 mg/kg for 6 days marked effects on brain AChE Intraperitoneal injection: Rats [86 ] 4.5 mg/kg ( female) a) injected into animals a) i: 100%) mortality fed a casein-free diet for 30 days or b) into animals fed a 15% b) 12 67% mortality casein diet for 30 days Subcutaneous injection: Chickens Unreported No muscular weakness or paralysis [88] (administered in 3 successive observed doses “adequate to produce a severe response”) Intraperitoneal injection: Rats [89] a) 1 mg/kg/day (female) a) 13 All treated rats exhibited signs of acute and parathion poisoning (, respira­ b) 1.3 mg/kg/day b) 13 tory difficulty, cyanosis). A progressive myopathy developed in rats receiving I and 1.3 mg/kg/day. Less than 5% of muscle fibers studied were affected. Intraperitoneal injection: Rats “4 or more”/ Both doses produced similar depressions [91] 1.0 and 1.5 mg/kg (animals ( male) dose of brain and RBC ChE: 20-25% and killed at 2 or 5 hours slightly less than 50% inhibition, re­ after parathion injection) spectively. No gross signs of parathion poisoning were observed. At 2 hours after parathion injection, plasma levels of free corticostcronc increased by 75% . Oral: Mice Unreported No significant alteration in the metab­ [92 1.3, 2.6, or 5.3 mg/kg/day ( male) olism of androgens. for 5 days

25 TABLE III-4 (c o n t i n u e d ) Route of Administration Species Number Results Reference Inhalation: a) 0.04-230.0 mg/cu m a ) Rats a) 34/group a) LC50 = 84.0 mg/cu m [Edge- for 4 hours (male) RBC ChE50 = 5.4 mg/cu m wood Plasma ChE50 = 7.3 mg/cu m Arsenal b) 0.015-37.1 mg/cu m b) Dogs b) 4 /group b) LC50 = greater than 37.1 mg/cum study] for 4 hours (male) c) 0.01 mg/cu m c) Rats c) 80/group c) 1 rat died on the 1st day. RBC ChE 7 hours/day, 5 days/ (male) activity decreased to 69% of normal week, for 6 weeks during week 4. d) 0.10 mg/cu m 7 hours/ d) ” d) 80/group d) No toxic signs were seen. RBC ChE day, 5 days/w-eek, activity decreased to 57% of normal for 6 weeks after 1 week of exposure. e) 0.74 mg/cu m 7 hours/ e) e) 80/group e) Animals developed congestion of the day. 5 days/week, lungs. RBC ChE activity decreased for 6 weeks to 58% of normal after 1 week of exposure. RBC ChE activity de­ creased to 16%i of normal after 5 weeks of exposure. f) 0.001 mg/cu m 7 f) Dogs f) 6 /group f) No significant inhibition of either hours 'day, 5 days/ (male) RBC or plasma ChE activities. week, for 6 weeks g) 0.01 mg/cu m 7 hours/ g) g) g) RBC ChE activity decreased to 79% day. 5 days/w'eek. of normal after 2 weeks of exposure; for 6 weeks 101% of normal at the end of the 6-w'eek exposure period. After 6- weeks exposure, the plasma ChE activity was depressed to 58% of normal. h) 0.20 mg/cu m 7 hours/ h) h) h) RBC Che activity decreased to 54% day, 5 days/week, of normal after 2 weeks of exposure; for 6 weeks plasma ChE activity at this time was 26% of normal. Oral: a) 0.1 8-7.0 mg/kg a) Rats a) 10/group a) RBC ChE50 = 2.6 mg/kg [Edge- (single doses) (male) plasma ChE50 = 2.5 mg/kg wood b) 0.50. 1.26, 2.5, and b) Dogs b) 4/group b) RBC ChE50 = 1.5 mg/kg Arsenal 10.0 mg/kg (male) plasma ChE50 = 1.7 mg/kg study] (single doses) c) 0.25 mg/kg, 5 days/ c) Rats c) 80/group c) RBC and plasma ChE activities were week, for 6 weeks (male) inhibited to 46% and 52% of normal after 6 weeks of exposure. d) 0.10 mg./ kg, 5 days/ d) " d) ” d) Lowest RBC ChE activity observed week, for 6 weeks was 78% of normal after 4 weeks of exposure. Plasma ChE activity in­ hibited to 20% of normal after 2 weeks of exposure. e) 0.05 mg/kg. 5 days/ e) e) ” e) No significant inhibition of RBC or week, for 6 weeks plasma ChE activities. f) 0.50 mg/kg. 5 days/ f) Dogs f) 6/group f) RBC and plasma ChE activities were week, for 6 weeks (male) 42% and 15% of normal, respec­ tively, after 6 weeks of exposure. g) 0.10 mg/kg. 5 days/ g) g) ” g) RBC and plasma ChE activities were week, for 6 weeks 80% and 61% of normal, respec­ tively, after 6 weeks of exposure. h) 0.05 mg/kg, 5 days/ h) ” h) ” h) RBC and plasma ChE activities were week, for 6 weeks 83% and 54% of normal, respec­ tively, after 6 weeks of exposure. 26 TABLE III-4 (c o n t i n u e d ) Route of Administration Species Number Results Reference intraperitoneal injection: Rats [97] a) 3.0 mg/kg, given as (female) a) 5 a) Symptoms of poisoning in the dams. a single ip injection High incidence of resorptions and to pregnant rats on reduced fetal and placental weights. the 11th day after One edematous fetus out of 28. insemination b) 3.5 mg/kg, given as b) 5 b) Symptoms of poisoning in the dams. a single ip injection High incidence of resorptions and to pregnant rats on reduced fetal and placental weights. the 11th day after No fetal malformations reported. insemination Subcutaneous injection: Rats a) Signs of parathion poisoning, includ­ [98] a) 2 mg/kg/day for a) 28 ing salivation, lacrimation, diarrhea, 4 davs and tremors observed in test ani­ mals. 2 of 28 rats died after the 2nd injection. Severe depression of blood and brain AChE’s. b) 1.5 mg/kg/day for 52 rats used b) Signs of parathion poisoning in dams. 4 days beginning on in experiments Brain AChE activity of pups was days 1, 7, or 13 of b) and c) normal but wasdepressed in the gestation dams. No fetal resorptions were observed. c) 2.0 mg/kg/day for c) Signs of parathion poisoning in dams. 4 days beginning on 4 rats died, 3 during the 3rd tri­ days 1, 7, or 13 of mester. Brain AChE activity of pups gestation. was normal but was depressedin the dams. No fetal resorptions were observed. Intraperitoneal injection: Mice Unreported 12 mg/kg administered on gestational [99] injected ip with single doses (female) days 12,. 13, and 14 produced 90% of 4, 8, 10. 11, or 12 mg/kg incidence of deaths in utero. 12 mg/kg at varying times during administered on gestational days 8, 9, gestation. Laparotomy and 10 produced 27% incidence of performed on mice on the deaths in utero. Parathion significantly 19th day of gestation. reduced fetal body weight. female rats injected with 0.5 mg/kg/day died after A single-trial, passive-avoidance task was used to 20 days of continuous dosing. The symptoms evaluate learning. Blood and brain ChE activities preceding death of the animals were similar to were determined. Mice used in the acute phase of those observed in acutely poisoned rats. From the study were starved for 18 hours prior to oral these results the investigators concluded that . . administration by intubation of parathion (in continued exposure to sublethal doses of parathion polyethylene glycol) at a dose of 6 mg/kg. At least results in subacute poisoning in rats and suggests 20 animals in each group were used for the the possibility of a cumulative action by parathion behavioral tests and at least 6 animals per group in other animals after continued exposure to the for the ChE determinations. This dose produced insecticide.” death in about 10% of the animals, usually within The effect of parathion on avoidance behavior 15 minutes of administration. The animals died in the rat was reported by Bignami and Gatti.82 with typical signs of parathion poisoning: tremors, Parathion was given orally to rats previously convulsions, and respiratory distress. Parathion trained to give avoidance responses in fully auto­ was administered at various times prior to the mated shuttle-boxes. No modifications of behavior learning trial and at various times prior to retest­ were observed during daily doses of 1 mg/kg of ing. The maximum effect on performance, at a parathion given for 9 days, of 2 mg/kg given for 2 dose of 6 mg/kg, occurred when parathion was ad­ days, and of 5 mg/kg given for 4 days. ministered within the first hour before the learning In 1973, Reiter et al83 reported the effects of trial; about 3 1% of the mice treated within this parathion on ChE activities and learning in mice. period remained on the platform during retesting. 27 Parathion in oral doses of 4 mg/kg, 8mg/kg, and Williams found that single doses of parathion in­ 12 mg/kg was also administered to groups of mice hibited liver and brain AChE to a greater extent 45 minutes prior to the learning trial. As in the when animals were fed an essentially protein-free case of the 6 mg/kg dose, these doses of parathion diet. resulted in impairment of performance. However, The importance of plasma ChE and RBC ChE in the 8 mg/kg dose killed 19% of the mice while 12 the protection of acetylcholinesterase at tissue mg/kg killed 40% of the animals tested. Thirty sites was clearly demonstrated by Karczmar and minutes after administration of an oral dose of 6 Koppanyi.71 In one series of experiments, they in­ mg/kg of parathion, AChE and ChE activities in fused groups of 10-18 atropinized dogs with either both blood and brain declined to 30-55% of con­ isotonic saline, Tyrodes’ solution, glucose, or a trols. To determine the effects of subacute 0.2% solution of ACh in saline. Plasma and RBC parathion treatment, mice were given daily sc in­ ChE’s were measured manometrically before and jections of parathion for a period of 6 days in after the infusions. The maximal hemodilution doses ranging from 1 to 4 mg/kg. This treatment produced by the infusions (concentration of had no effect on passive-avoidance learning. How­ hemoglobin decreased by 26i 6% ) was accom­ ever, marked effects were seen on AChE and ChE panied by a decrease in the activities of the ChE’s activities in blood and brain. It is interesting to of the blood of 28t 7%. When these dogs were note that when measured 18 hours after the sixth given iv injections of standard doses of ACh and sc injection, the 2 mg/kg dose produced the same BCh (benzoylcholine), the pressor responses degree of inhibition which was present Vz hour elicited in that way were about twice those ob­ after the 6 mg/kg acute dose, namely, a 55% tained in the same dogs before the infusions. reduction in brain AChE, with no effect on learn­ Reduction of the activities of the ChE’s of the ing. blood by dilution with the saline solutions was The results indicated that acute exposure to high concluded to have enhanced the abilities of doses of parathion impaired passive-avoidance choline esters degradable by these enzymes to learning in mice and that maximal changes in ChE stimulate sympathetic ganglia and the adrenals. activity correlated closely with peak behavioral ef­ In a second series of 34 experiments, normal fects. Contrary to these results were those in mice dogs were transfused serially for up to 15 times exposed subacutely to parathion. No effects on with blood from heparinized, atropinized dogs that learning were observed in mice injected subcu- had been given iv doses of DFP (2.5 to 4.0 mg/kg) taneously with parathion for 6 days despite the to inactivate the ChE’s in their bloods. In this way, fact that significant depressions in blood and brain the bloods of the recipient dogs were diluted with ChE’s occurred. The authors concluded that these respect to both RBC and plasma ChE’s without animals were able to compensate for increased any general hemodilution. In this series of experi­ amounts of ACh at central synapses. ments, a 40% decrease in the activities of the The possibility that potentiation may occur withChE’s in the blood enhanced the pressor response combinations of two or more anticholinesterase to injected ACh but not that to injected agents has been discussed by DuBois.84 Of particu­ methacholine (MCh). When additional transfu­ lar interest has been the combination of EPN and sions had reduced activities of the ChE’s of the malathion which causes potentiation of the acute blood to 10 to 15% of the normal values, the toxicities of the components.85 DuBois reported responses to both injected ACh and MCh were in­ that parathion showed simple, additive acute tox­ creased fourfold. At this time, iv injections of DFP icity with EPN, Dipterex, Systox, Co-Ral, and Di- (0.25 to 0.50 mg/kg) into these dogs enhanced Syston and less than simple, additive acute toxicity still further the responses to injected BCh but not with malathion and Guthion. Potentiation of tox­ those to injected ACh, presumably by inhibiting icity was not observed for parathion. all, or at least most, of the remaining BuChE in Other factors which may influence sensitivity to the blood and tissues of these dogs. parathion include diet and preexposure levels of A third group of 15 atropinized dogs was given plasma and RBC ChE. In a study of the effects of sufficient DFP to inhibit completely the ChE’s of diet, Casterline and Williams86 found that low all tissues. The responses to injected ACh and BCh protein diets increased the susceptibility of rats to were increased. These animals were then trans­ parathion. An intraperitoneal dose of 4.5 mg/kg fused with blood from normal dogs to restore the resulted in 100% mortality in rats fed a casein-free activities of the ChE’s of their bloods to approxi­ diet for 30 days vs one of 67% in rats fed a 15% mately normal levels. Although the ganglionic casein diet for a similar period. Casterline and AChE and the BuChE of the intestine were still in­ 28 hibited in these dogs, the responses to injected jected rats demonstrated several signs of acute ACh and BCh were similar to those recorded be­ parathion poisoning 20-30 minutes after each in­ fore the administration of DFP. jection. These signs included tremors, respiratory Eight control experiments were carried out in difficulty with tachypnea and mild cyanosis, lethar­ which both the donor and the recipient dogs were gy, and decreased responsiveness to sensory stimu­ normal. The responses in the recipient dogs to in­ li. These lessened in severity during the next 2-3 jected ACh, BCh, MCh, nicotine, and epinephrine hours. Animals receiving both doses were sacri­ varied from the mean pre-transfusion magnitudes ficed on days 1, 3. 5. 8, 10, 12, and 14 after the by less than 15% after a series of transfusions. first injection. Six rats died as the result of These experiments demonstrated apparently the parathion toxicity (the doses administered ability of the ChE’s of the blood to react with cir­ represented approximately 0.5-0.75 the LD50 for culating cholinergic and anticholinesterase com­ this species); 26 animals were killed by injection pounds and to reduce their impacts upon active of pentobarbital ; then sections of their sites of effector organs. Accordingly, plasma and quadriceps, gastrocnemius, and soleus muscles RBC ChE’s have been considered to have impor­ were prepared and studied microscopically. tant buffer-like roles in protecting the AChE at According to the author, the animals receiving 1 neuroeffector junctions and other active sites from mg/kg of parathion/day developed a progressive the inhibitory actions of parathion and other or- myopathy which reached a peak on day 8, after ganophosphorus anticholinesterase compounds. which the number of new lesions diminished. Rats Recovery of an animal from parathion poisoningreceiving 1.3 mg/kg/day developed large numbers and its reestablishment of normal susceptibility to of completely disrupted and phagocytized muscle intoxication by OP compounds depend upon the fibers by the 3rd day. Although the appearance of reestablishment of normal activities of ChE’s in new lesions progressed to day 5, their fibers did blood and tissues. Although parathion is classified not continue to undergo degeneration and sub­ as an “irreversible” inhibitor of ChE, the reaction sequent phagocytosis. Kibler reported that less is reversible, at least initially.87 Grob87 demon­ than 5'/i of muscle fibers studied were affected strated in vitro that the combination between and that this percentage “is far too small to parathion and ChE’s from human plasma, RBC’s, produce clinical weakness.” The effects observed and brain was partially reversible during approxi­ were postulated by the author to be due to exces­ mately the first 3 hours after addition of the com­ sive ACh at the neuromuscular junction caused by pound to the enzyme, and irreversible after that inhibition of AChE. The doses of parathion ad­ time. DuBois et al*° demonstrated that in rats acu­ ministered were very large. No mention was made tely poisoned with 5 mg/kg of parathion brain ChE of demyelination of nerves, but the author may not activity regenerated from an observed low of 5.8% have looked at nerves. after */2 hour to 97% of normal activity in 4 hours. In 1975, Johnson9" published a review article on In animals, parathion has not been shown to neurotoxicity caused by organophosphorus esters. exert toxic effects other than those related to in­ The study by Barnes and DenzHH was referenced hibition of AChE. The ability of some OP com­ along with a later study by Johnson on the neu­ pounds to produce persistent paralysis accom­ rotoxicity of certain organophosphorus com­ panied by toxic changes in distal axons and de- pounds, including paraoxon. Paraoxon did not myelination of the sheath of the damaged axon has produce ataxia. Johnson’s paper provides an in­ focused a great deal of interest on the part of teresting discussion of the possible mechanism of researchers in this effect. Barnes and Denz™ found delayed neurotoxicity. that neither parathion nor paraoxon produced a The stress of exposure to parathion has been paralytic effect in chickens whereas TOCP, DFP, shown91 to result in increased plasma levels of free and mipafox did. Severe cholinergic responses but corticosterone (PFC) in rats. Murphy91 attributed no demyelinating lesions were observed in this action of parathion to its stimulation of pitui­ chickens after 3 successive doses of parathion tary ACTH since depletion of adrenal ascorbic (amount unspecified). The chickens were observed acid accompanied the increase in PFC. The 2 for 3 weeks after the third dose. lowest doses of parathion tested (1.0 and 1.5 In 1972, Kibler89 reported that parathion-in- mg/kg) produced 20-25% inhibition of brain ChE duced histologic evidence of skeletal muscle and approximately 50% inhibition of RBC ChE. necrosis in rats. Thirteen Sprague-Dawley rats No gross signs of poisoning were observed in these received daily ip injections of parathion at a dose animals. PFC levels increased by about 75% two of 1 mg/kg and 13 received 1.3 mg/kg. All in­ hours after injection of parathion. 29 In 1974, Thomas92 reported on the effects of RBC and plasma ChE activity levels were deter­ parathion and other pesticides on the mouse mined by an automated colorimetric procedure. reproductive system. Parathion in daily oral doses Normal horse serum was analyzed periodically as a of 1.3, 2.6, or 5.3 mg/kg was administered by gas­ standard. tric intubation for 5 days to male mice and effects (1) Acute Inhalation Toxicity in Male Rats on the reproductive system determined by measur­ and Male Dogs ing the uptake and subsequent metabolism of 1,2- In acute inhalation toxicity tests, groups of 34 3H-testosterone by the prostate gland. The uptake rats were exposed during 4 hours to concentra­ of tritiated testosterone was not affected by tions of parathion ranging from 0.04 to 230.0 pretreatment with parathion. Regardless of the mg/m3 in a 1,000-liter dynamic flow chamber. dose of parathion, no changes in the pattern of Groups of 4 dogs were exposed to parathion for 4 radiosteroids were detected. Thomas concluded hours at 5 concentrations ranging from 0.015 to that parathion did not produce any significant 37.1 mg/m3. The LC50 for rats was estimated to changes upon the uptake and metabolism of an­ be 84.0 mg/m3 while that for dogs was determined drogens by sex accessory organs of the mouse. to be greater than 37.1 mg/m3 (the highest dose (c) New Unpublished Research Data tested). The ChE50 for RBC ChE in the rat was Based on the limitations of the aforementioned 5 4 mg/m3 and that for plasma ChE was 7.3 data, the decision was made by NIOSH in late mg/m3. In the experiment with dogs, the investiga­ 1973 that extrapolation from the then existing data tors were unable to estimate a ChE50 dose for this to a recommended safe environmental limit (ie, species because of the pronounced and incon­ safe airborne concentration) for man could not be sistent effects on blood ChE activity by the expo­ achieved with an acceptable degree of scientific sure concentrations used. No deaths occurred in reliability. In order to obtain additional informa­ dogs exposed to the aforementioned concentra­ tion regarding the inhalation toxicity of parathion tions. However, blood ChE activities were signifi­ in experimental animals, and particularly inhala- cantly depressed by all exposure concentrations. tion-to-oral toxicity ratios, research was un­ These data seem rather remarkable because the dertaken for the Institute by the Toxicology Divi­ lowest concentration produced nearly the same in­ sion, Biomedical Laboratory, Edgewood Arsenal. hibitions of the activities of RBC and plasma The research described below was conducted dur­ ChE's as the largest concentration, and in close to ing the period July 1974-December 1975, during the same times (1.5 days vs 1.0 day). The concen­ which time the parathion criteria document was trations referred to above differed by a factor of held in abeyance. more than 2,470 times, so that the Ct doses of The research consisted of 2 parts: (1) acute in­ parathion received by the groups of dogs exposed halation and oral toxicity studies on rats and dogs; to the two extreme concentrations would be ex­ and (2) subacute inhalation and oral toxicity stu­ pected to differ by this same factor. dies using the same 2 species. Purebred adult male At the lowest exposure level for dogs, 0.015 beagle dogs and adult male Sprague- mg/m3, the RBC and plasma ChE activities after 4- Dawley/Wistar strain rats were used in the experi­ hour exposure were 62% and 18% of normal, ments. The effects of the insecticide on both RBC respectively. Twenty hours after the termination of and plasma ChE were used to calculate inhalation- exposure the values were 49% and 14% of normal, to-ora! toxicity ratios for rats and dogs. respectively. Fourteen days after exposure the These ratios were then used by NIOSH to deter­ RBC and plasma ChE: activity levels had risen to mine a predicted safe environmental limit for man 58% and 75% of normal, respectively. The data based on a known safe human ingestion dose (see are presented in Tables XVI-5 through XVI-8. Chapter V, Development of Standard). Similar results were observed at airborne parathion Technical grade parathion of 99.3% purity was concentrations of 0.15 mg/nv! and greater; the used in the inhalation and oral experiments. RBC and plasma ChE activities were significantly Chamber air samples collected during the inhala­ depressed. tion phases of the work were analyzed to deter­ Tremors, convulsions, respiratory difficulty, and mine whether any paraoxon was present in the air excessive salivation were seen in rats exposed to being breathed by the animals. No paraoxon or parathion concentrations of 50 mg/m3 or greater. any other more toxic derivative of parathion was The EC50's for tremors and convulsions were esti­ detected in any samples. Particle diameters of the mated to be 73.7 mg/m3 and 1 10.6 mg/m3, respec­ aerosols generated, as determined by use of a tively. At the lowest level tested, 26.1 mg/m3, oc­ Rochester cascade impactor, were 1.0-2.0 microns. casional sneezing, diarrhea, urination (scrotal area 30 wet with urine), lethargy, and “wet dog shakes” cordingly, groups of 6 dogs were exposed to air­ were observed in test animals. The highest concen­ borne parathion concentrations of 0.001, 0.01, and tration that did not cause deaths was 35.0 mg/m3. 0.20 mg/m3 for 7 hours/day, 5 days/week, for 6 A no-effect concentration was not determined for weeks. RBC arid plasma ChE activity determina­ the rat in this series of exposures. At the end of tions were made after 1 day and 1, 2, 3, 5, and 6 the 4-hour exposure to parathion at a concentra­ weeks of exposure to aerosols of parathion and at tion of 0.04 mg/m1, the average RBC ChE activity various times following cessation of exposure. The of the exposed rats was 84% of normal. RBC and plasma ChE activity values are shown in (2) Subacute Inhalation Toxicity in MaleTable XVI-10. With the 0.001 mg/m3 exposure Rats and Male Dogs concentration both the RBC and plasma ChE ac­ Groups of 80 male rats were exposed for 7 tivities were not inhibited significantly during the hours/day, 5 days/week for 6 weeks to aerosol 6-week exposure period and the 6-week postexpo­ concentrations of 0.01, 0.10, and 0.74 mg sure period. Thus, the lowest exposure concentra­ parathion/m3. Toxic signs were not seen in the rats tion constituted a safe level on the basis of inhibi­ exposed to the 0.01 and 0.10 mg/nr! concentra­ tion of blood ChE’s. After 2 weeks of exposure to tions of parathion except for 1 animal that died on 0.01 mg/m3, of parathion the RBC and plasma the first day of exposure to 0.01 mg parathion/m3. ChE activities were 79% and 70% of normal, Microscopic examination revealed congestion of respectively (average of 6 dogs). After a 6-week the lungs with the highest parathion concentration exposure to 0.01 mg/m3, the corresponding activi­ used, 0.74 mg/nr’. Two rats died, one on the 10th ties were 101% and 58%, respectively. With 0.20 day of exposure and one on the 28th day of expo­ mg parathion/m3, the effects on RBC and plasma sure. Both animals had congested lungs on gross ChE were great. After 2 weeks of exposure to this examination. The lowest dose tested, 0.01 mg/m3, concentration, the RBC and plasma activities were was estimated from the acute toxicity phase of the 54%> and 26% of normal, respectively. The RBC study to be a no-effect dose. and plasma ChE activities decreased to 41% and The average blood hematocrit value, 47.2 mg%, 36% of normal, respectively, after 6 weeks of ex­ obtained from 9 exposed rats after the last expo­ posure; the RBC ChE activity did not return to sure to parathion at a concentration of 0.74 mg/nr* normal until 4 weeks after termination of the ex­ was not significantly different from that obtained posure. All 3 parathion concentrations exerted from 4 control animals. The exposed rats gained greater inhibitory effects on the plasma enzyme weight throughout the exposure and postexposure than on that of the RBC’s. Other than effects on periods with all 3 parathion concentrations. blood ChE’s, no toxic signs were observed in the With the lowest exposure level, 0.01 mg/m3, the dogs with any of the 3 exposure concentrations. greatest effect of the parathion on RBC ChE oc­ (3) Acute and Subacute Oral Toxicity in curred during week 4, when the activity decreased Male Rats and Male Dogs to 69% of normal. In contrast, the RBC ChE ac­ Preliminary to subacute feeding studies, 50 adult tivity decreased to 57% and 58% of normal after male rats and 20 adult male dogs were used to one week of exposure to 0.10 and 0.74 mg determine the acute 24-hour LD50’s following sin­ parathion/m3, respectively. After 5 weeks’ expo­ gle oral doses of parathion in corn oil. These sure to an airborne parathion concentration of values were 6.85 (6.18-7.60) mg/kg and 8.27 0.74 mg/m3 the RBC ChE activity had been (4.79-14.29) mg/kg for male rats and male dogs, lowered to 16% of normal. In almost all cases, the respectively. The results indicate that parathion is RBC ChE was inhibited to a greater extent than approximately equitoxic when administered orally the plasma ChE. Of the 3 concentrations, 0.01 mg to these 2 species. Tables XVI-11 and XVI-12 list parathion/m3 produced the least inhibition of the the dose levels administered, the percent of ChE activity of either RBC’s or plasma. The inter­ animals of each species responding at each level, mediate concentration, 0.10 mg parathion/m3, ex­ the average percent inhibition of RBC and plasma erted a moderate inhibitory effect whereas the ChE’s, and the Bliss statistical analysis of the data. highest, 0.74 mg/m3, concentration produced Acute ChE50 values were also determined for marked inhibition. Table XVI-9 summarizes these male rats and male dogs. The dose range for data. groups of 10 rats was 0.18 to 7.0 mg/kg of The results of the acute studies with dogs in­ parathion; 7 different doses in corn oil being used. dicated that this species is more sensitive than rats Dogs in groups of 4 were given the following oral to inhaled parathion, as shown by the effects on doses of parathion in corn oil: 0.50, 1.26, 2.5, and ChE activities in the blood of the dog. Ac­ 10.0 mg/kg. In both species, blood samples for ChE activity determinations were taken 24-hours weekly. Blood samples for ChE determinations postexposure. were taken at 1, 2, 4, and 6 weeks during expo­ For male rats the RBC and plasma ChE50 sure and at 1,2, 4, and 6 weeks postexposure, if values were determined to be 2.6 (2.1-3.1) and required. 2.5 (2.1-3.0) mg/kg, respectively. In male beagle The effects on the blood ChE’s of the dog by dogs, the ChE5() values for RBC and plasma were these daily doses of parathion are presented in found to be 1.5 (1.1-2.1) and 1.7 (0.9-3.0) mg/kg, Table XVI-18. The 0.50 mg/kg dose produced respectively. Like the LD50 data, the ChE50 after 6 weeks about 58% inhibition of RBC ChE values estimated for the 2 species indicate that and about 85% inhibition of the plasma enzyme. orally administered parathion is approximately With respect to the RBC ChE activity, the 0.10 equitoxic in male rats and male beagle dogs. These mg/kg and 0.05 mg/kg dose levels produced ap­ data are presented in Tables XVI-13 through XVI- proximately equivalent results. With 0.10 mg/kg of 16 . parathion, the RBC activity was 8 O'/i of normal Two hundred and forty rats received daily doses after 6 weeks of exposure and with the 0.05 mg/kg of 1 ml/kg of corn oil, 5 days/week, for 6 weeks dose, 83%. However, the plasma ChE activity was and served as controls. Another 240 animals were inhibited to a significantly greater extent by the divided into 3 groups of 80 rats each. These daily dose of 0.1 mg/kg of parathion than by the groups of rats received 1 ml/kg of corn oil con­ lower dose. No toxic signs were observed in any of taining parathion in concentrations of 0.25 mg/ml, the test or control dogs during or after exposure to 0.10 mg/ml, or 0.05 mg/ml. All rats were weighed these oral doses of parathion. There was no signifi­ daily on 5 days/week and dosed, presumably by cant effect on bodv weight in any of the exposed stomach tube, on a ml/kg basis. With the highest animals. The only conclusion from these results is dose, 10 control and 10 exposed rats were sacri­ that a daily dose of 0.05 mg/kg may not produce ficed for blood sampling at 1,3, 4, 5, and 6 weeks any deleterious inhibition of the ChE’s of the during oral dosing, and at 1,2, 4, and 6 weeks blood of the dog during 6 weeks and that the 2 postexposure. With the 2 lowest doses, RBC and highest doses probably are not safe for repeated plasma ChE activities were determined at 1,2, 4, daily oral ingestion. and 6 weeks during exposure and at various times Experiments were performed also to determine following the cessation of oral dosing until the rates of recovery of the RBC and plasma ChE complete restoration of enzyme activity had oc­activities in male rats and dogs. A total of 60 rats curred. The results of this study are given in Table and 4 dogs were administered single oral doses of XVI-17. The highest daily dose, 0.25 mg/kg of parathion in corn oil of 2.8 mg/kg and 2.5 mg/kg, parathion inhibited about 54% of RBC ChE activi­ respectively. Twenty control rats received corn oil ty and about 48% of plasma activity by the end of alone. No mention was made by the investigators the 6-week exposure period. No significant blood of control dogs. Rats were bled at 4 hours and 1, ChE inhibition resulted from the 0.05 mg/kg dose. 2, 3, 7, and 14 days postexposure; dogs were bled The lowest RBC ChE activity observed at the in­ at 1, 11, 15, 29, and 36 days postexposure. The termediate dose of 0.10 mg/kg was 78% of normal rates of recovery for both RBC and plasma ChE (following the 4th week of exposure). Inhibition of activities agree with those reported previously in plasma ChE was less marked in general than that the criteria document. The RBC ChE activity of the RBC enzyme. Thus, the 2 lowest doses ex­ recovered at the following rates: 1.7%/day and erted no profound effects on either the RBC or 1.6%/day for male rats and male dogs, respective­ the plasma ChE and can be considered safe oral ly. For rats, the plasma ChE activity returned at a doses for rats. None of the test animals exhibited rate of 3.1 %/day whereas in dogs the rate was toxic signs of parathion poisoning either during or 5.5%/day. The results are presented in Tables after exposure. Weight gained by parathion-treated XVI-19 and XVI-20. rats was not significantly different from that gained by the control animals. Carcinogenicity, Mutagenicity, Teratogenicity In a similar manner, the effects of orally ad­ Malformations in the embryonic skeleton of the ministered parathion on the RBC and plasma Japanese quail by parathion have been reported by ChE's of dogs were determined. Twenty-four adult Lutz-Ostertag et aP and by Meiniel et al.iM These male beagle dogs in groups of 6 each were dosed workers either injected eggs with a 0.1% solution orally 5 days/week for 6 weeks with one of 4 con­ of parathion or immersed the eggs in a 2% solu­ centrations of parathion in corn oil: 0.00, 0.05, tion of parathion-in-acetone for 30 seconds. The 0.10, or, 0.50 mg/kg. All dogs were weighed dose received by the embryos cannot be calculated 32 but must have been very high. All embryos from dams injected with parathion during the latter eggs treated with parathion by immersion showed third of pregnancy were significantly lower than abnormalities, principally localized in the cervical those of controls. By the second week, body region. Malformations of the axial skeleton and weights were normal in pups from all treated reductions in the length of the spine were com­ groups. The authors’ statement that the slower mon. Similar results from studies on hen and quail body growth and later development may be at­ eggs were published by Meiniel in 1973.95 tributable to poor maternal behavior appears Khera and Bedok96 obtained similar results in reasonable in light of the fact that brain AChE ac­ chick and duck embryos. They injected 1 mg of tivity was normal in the pups at birth and also to parathion (presumably in propylene glycol) intotheir observations that the parathion-treated dams the yolk sac of preincubated or 4-day-incubated appeared to pay less attention to their pups than chick eggs and 4-day-incubated duck eggs. Control unpoisoned mothers. eggs of both species were injected with sterile In 1975, Harbison99 reported the results of his propylene glycol. Parathion treatment resulted in study on parathion-induced toxicity during characteristically tortuous and shortened vertebral prenatal development in mice. Mice were injected columns composed of abnormal vertebral bodies ip with parathion at doses of 4, 8, 10, 1 1, or 12 (fused neural arches). mg/kg. Control mice were injected with corn oil. Kimbrough and Gaines97 reported the effects of Laparotomy was performed on pregnant mice on parathion on the rat fetus. Intraperitoneal injec­ gestational day 19. At this time, the number and tions of parathion in dams in doses of 3.0 and 3.5 positions of live, dead, and resorbed fetuses were mg/kg caused a high incidence of resorptions and noted and then fetuses were removed and reduced the weights of the fetuses and placentas. weighed. The greatest effects were observed when With the higher dose, one edematous fetus was ob­ parathion was injected during gestational days 12, served out of a total of 28. However, the investiga­ 13, and 14. During this period, a dose of 12 mg/kg tors emphasized that only those doses of parathion killed 90% of the fetuses, while the same dose was that produced toxic symptoms in the dams af­ lethal to 27% of the fetuses in utero during gesta­ fected the fetus. tional days 8, 9, and 10, the period of early or­ Talens and Woolley98 reported the effects of ex­ ganogenesis. A dose of 12 mg/kg was not lethal to posure to parathion during gestation on develop­ the maternal animal, ^he body weights of surviv­ ment in the rat. Female rats were subcutaneously ing fetuses were significantly reduced by parathion injected with 2 mg/kg of parathion for 4 days and treatment. As in the case of resorptions, a gesta­ then killed at various intervals for determination of tional period susceptibility was observed; the blood and brain AChE activities. Cholinergic signs developing organism appeared to be more of poisoning, including salivation, lacrimation, susceptible to parathion-induced reduction in body diarrhea, and tremors were observed in the test weight during late organogenesis or the fetal matu­ animals; 2 of 28 animals died after the second in­ ration period. Data were also presented showing jection. Twenty-six hours after the last injection, that phénobarbital greatly protected the develop­ the AChE activities in the neocortex, brain stem, ing fetus from the effects of ip-injected parathion. remaining brain, and blood were 21%, 40%, 19%, Weis and Weis100 subjected fertilized killifish and 49% of control activities, respectively. To (Jundulus heterclitus) eggs to parathion at concen­ determine effects on development, pregnant rats trations of 1 and 10 ppm. The insecticide was dis­ were injected subcutaneously with 1.5 or 2.0 solved in acetone and added to dishes containing mg/kg parathion daily for 4 days beginning on day the eggs at the 8-16 cell stage, in filtered sea 1, 7, or 13 of gestation. Signs of poisoning were water. When controls had reached the 19-20 cell seen in the dams (most severe when administered growth stage, embryos in 1 ppm parathion were in during the third trimester). Four of 52 rats in­ stage 17-18 while those in 10 ppm were in stage jected with the highest dose died, 3 during the 17. Sixty-four percent of eggs exposed to 10 ppm third trimester. In surprising contrast to the effects of parathion successfully formed axes vs 93% in in the dams, the brain AChE activity of the pups controls. After 3 days in parathion, 10-12 embryos at birth was normal in all treated groups. At birth, were removed from the 1- and 10-ppm dishes, the average litter size of the parathion-treated washed, and placed in clean sea water. Fifty per­ dams did not differ from that of controls. Thus, cent of the group exposed to 10 ppm parathion fetal resorption did not occur, in contrast to the developed a thin feebly-beating tube with rudimen­ results previously reported by Kimbrough and tary chambers stretching between the yolk and the Gaines.97 Average birth weights of pups born to embryo, instead of a normal heart. The authors 33 stated that other tissues and spontaneous move­ it did not materialize. Results of the carcinogenesis ment were normal. The concentrations of bioassay of parathion have not been made availa­ parathion did not produce death in the embryos. ble to NIOSH as of July 1, 1976. When the bioas­ Because of the species used and the nature of the says are completed and the results made available exposure, it is impossible to extrapolate these to NIOSH, appropriate action will be taken. results to man. The data presented in this section relating to the In 1973, Mohn101 reported on the mutagenic testing of parathion for carcinogenic, mutagenic, potential of parathion and other insecticides. The and teratogenic activity in various mammalian and induction of 5-methyltryptophan (5-MT) resistant nonmammalian species indicate that the com­ mutations in Escherichia coli by parathion was pound is not active in these respects. It is con­ evaluated. A concentration of 20/xg 5-MT/ml was cluded that parathion is unlikely to produce muta­ used and the inoculum contained 300,000-500,000 tions, terata, or cancer in humans. cells/ml. Cultures with a low spontaneous mutation frequency were used. The test system was sub­ Correlation of Exposure and Effect jected to 0.043 M parathion with no increased mu­ Evaluation of the literature pertaining to the ef­ tagenic activity observed; the number of 5-MT re­ fects of overexposure to parathion indicates that sistant mutations did not differ significantly from parathion is absorbable after inhalation,37,38 in- the spontaneous value. gestion,34-3* and impingement on conjunctival, cu­ In a 1975 review article dealing with mutagene­ taneous, or mucous membranes,1116-39'41 and in­ sis by pesticides, Fahrig102 compared the results of duces either subclinical (ie, depression of blood 4 studies with parathion. One of the mutagenicity ChE activity) or toxic (ie, signs/symptoms of studies was his own, which was published in 1973 parathion poisoning) effects, or both, depending and is described above.101 Two of the 4 studies on the amount absorbed. It is probable that the were apparently not published and are referenced high of parathion in lipoid media in­ in Fahrig’s review as personal communications. fluences its absorption through the skin and its dis­ The fourth study was performed by the author but tribution in the body. Parathion is converted in the data had not been published. Results in the 3 vivo and oxidized in the air to paraoxon22"25 which unpublished studies were obtained using the fol­ then reacts with, and inhibits the activity of, ChE lowing procedures: ( 1 ) spot test for back-muta- enzyme throughout the body.1 When the ChE ac­ tions to prototrophy in the 2 auxotrophic strains, a tivity of tissues is inhibited to a certain degree, 21 and a 742, of S. marcescens and for forward resulting in a disruption of normal enzyme func­ mutations to galactose prototrophy in the tion, a local condition of excess concentration of phenotypic galactose-negative Gal RS strain ofE. acetylcholine results. The signs and symptoms of coli\ (2) a liquid holding test for forward muta­ parathion poisoning arise from the totality of these tions to streptomycin resistance inE. coli-, and (3) individual local effects.1 The signs and symptoms a liquid holding test for mitotic gene conversion most frequently seen in parathion poisoning are at the ade2 and trp5 loci of 5. cerevisiae. Fahrig presented in Table III-1. reported that parathion was negative in all test Effects of parathion due to actions other than systems. inhibition of AChE are not proved. Karczmar and No papers have been found reporting the Koppanyi71 demonstrated that both RBC and production of carcinomas or other malignancies by plasma ChE’s may serve as “buffers,” protecting parathion. However, parathion is presently un­ neuroeffector ChE’s from inhibition by parathion. dergoing carcinogenesis bioassay by the National Experiments81,91''03 have shown that in animals Cancer Institute. (H Kraybill, written communica­ poisoned with parathion, the blood ChE’s are tion, March 1976) Male Osborne-Mendel rats depressed along with tissue ChE’s. Similar results have been fed parathion (ad libitum) for 18 in humans have been reported17'18; a decrease in months in their diets at concentrations of 30 and the activities of the blood ChE’s reflects concomi­ 60 ppm. Females of the same species and strain tant, but not necessarily proportional, reductions were fed parathion in their diets at 20 and 40 ppm in tissue ChE’s. Grob et al18 made a comparison of for the same length of time. Male and female mice the ChE activities of various tissues of two subjects (B«C3F1 strain) were fed 80 and 160 ppm who died after exposure to parathion with the parathion in their diets for 16 months. The obser­ average ChEi activities of 8 subjects who had vation periods for rats and mice were 6 months received no exposure to parathion or any other and 5 months, respectively. Although a prelimina­ anti-ChE agent and who had no disease of the ry report was anticipated during the Fall of 1975, CNS, liver, kidneys, or blood-forming organs. In 34 the 2 parathion-poisoned individuals, the percent­ administered in uniform oral daily doses. Ac­ age of control ChE activities for various tissues cordingly, if RBC ChE activity rather than plasma were: plasma—2.5%, RBC’s—16.5%, liver—60%, ChE activity were being monitored on a fixed rou­ kidney—88%: (one patient), cerebral cor­ tine it might provide a better warning that exces­ tex—26.5%, thalamus—52%, cerebellum—52.5%, sive absorption of parathion was occurring than pons—41%, and medulla—39%. Both patients would be provided by monitoring of plasma ChE developed marked signs/symptoms of parathion activity. In the situation where absorption of poisoning prior to death. The blood ChE’s and the parathion occurs on each of several serial days and urinary excretion of PNP are the only well-demon- then ends a few days before a preset monitoring strated and practical measures, from the viewpoint time, plasma ChE activity could return to normal of a compliance standard, of subclinical parathion before the blood sample was collected whereas the exposure presently available. Chronic occupational RBC ChE activity would be more likely to remain exposures to parathion are typified by repeated ab­ depressed. sorption of amounts of parathion which in single For this reason, selection of RBC ChE activity doses would not produce signs/symptoms of for routine biologic monitoring of blood to detect poisoning. However, the effect of repetition during exposure to parathion seems appropriate. Deter­ a sufficiently long period of high enough doses is mining both plasma and RBC ChE activities would to progressively inhibit tissue acetylcholinesterase not significantly increase the likelihood of detect­ to the point where decreased enzyme function ing progressive inhibition of tissue ChE above that results in the development of signs/symptoms of provided by monitoring RBC enzyme activity poisoning.80 Neither parathion nor its metabolites alone. cumulate in the body.50,51,104 However, the effects In summary, progressive depression of tissue of parathion on ChE’s may be cumulative depend­ ChE activity to a dangerous extent is believed to ing on the rate of enzyme inhibition. Grob et al18 be preventable by a biologic monitoring program demonstrated in humans that after inhibition by involving measurement of the activity of RBC parathion, RBC ChE activity returned at an ChE. Thus, by preventing a chronic but sustained average daily rate of 1-2% while the plasma ChE progressive depression of this blood enzyme, activity returned at the average rate of 3-4%/day. poisoning by parathion may be prevented. How­ If the daily inhibition of blood enzymes exceeds ever, it is highly unlikely that infrequent blood the daily recovery of ChE activity, there will ulti­ChE monitoring can prevent the occurrence of mately be a progressive decrease in tissue enzyme acute poisoning caused by a relatively massive ex­ activity to a level where signs/symptoms of poison­posure with a resultant precipitous decline in both ing will probably occur. Thus, monitoring of the the blood and the tissue ChE’s. In cases of serious RBC and plasma ChE activities serves as an in­ overexposures to parathion, such as by contamina­ dicator of what is happening to tissue ChE activity tion of a large area of skin by spills or splashes of levels. A review of the data presented1K,34,35,3i),R7,103 concentrate material, it is recommended that both reveals that both plasma and RBC ChE activity the RBC and the plasma ChE’s be measured, may be depressed simultaneously upon exposure to because the latter type of ChE is more sensitive to parathion, with the plasma enzyme inhibited to a inhibition by single large doses of parathion than greater extent (ie, preferentially inhibited). Thus, the RBC ChE,, the latter retaining still its value as plasma ChE activity is usually depressed more an indicator of cumulative absorption of parathion promptly and extensively and recovers more during a relatively long period of time. rapidly than RBC ChE activity when parathion is

35 IV. ENVIRONMENTAL AND BIOLOGIC METHODOLOGIES

Measurements of atmospheric concentrations of results indicated that the application of parathion parathion within the work areas of pesticidal is considerably less hazardous than its mixing and manufacturing and formulation plants and during loading into application equipment, especially in application of parathion-containing pesticides in orchard operations. Application by high-pressure agricultural operations provide an indication of the hand sprayers resulted in slightly higher at­ airborne levels of parathion encountered by wor­ mospheric concentrations of parathion than were kers in these operations. Various experiments have brought about by use of either air-blast ground rigs also been conducted in order to determine the ex­ or aircraft application equipment. The mean air­ tent of dermal exposure to parathion during borne concentrations resulting from these three similar operations. The results of such studies methods of application were 0.09, 0.03, and 0.05 define the need to wear proper protective clothing mg/m3, respectively. In contrast, mean airborne and equipment during potentially hazardous opera­ concentrations for mixing/loading operations in­ tions to prevent the occurrence of poisoning by volving ordinary water-wettable powder (WWP), parathion. Recommended environmental controls antidusting WWP, and liquid concentrates were and work practices are essential for the control of 2.15, 0.37, and 0.02 mg/m3, respectively. By utiliz­ occupational parathion exposure. ing filter pads attached to various parts of the Brown and Bush79 measured airborne parathion operator’s body and clothing (shoulders, forearms, concentrations at several locations in and near a thighs, back of neck, and chest), estimates of the parathion-manufacturing and -formulating plant. potential dermal exposure were made. Similar esti­ Concentrations of the toxicant ranged from 0.1 to mates of the potential respiratory exposure were 0.8 mg/m3. As mentioned previously, plant wor­ made by measuring the parathion absorbed onto kers experienced significant declines in their blood filter pads contained in respirators worn by the ChE activities. No mention was made of engineer­ subjects. The dermal parathion exposure of spray ing controls. operators was found to average 12.8 and 21.5 Several reports dealing with airborne concentra­ mg/sq ft/hr in high-pressure spraying and air-blast tions of parathion in fields and orchards following spraying, respectively. The calculated average spray application have appeared.58’105-111 In 1951, daily dermal exposure of the workers engaged in Stearns et al105 applied a spray mixture containing either high-pressure hand spraying or air-blast 4 lb of 15% wettable parathion and 10 lb of wetta- spraying was 7.7 versus 0.02 mg/kg for respiratory ble sulfur/100 gal to a 16-acre grove of grapefruit exposure (using the respirator pad technique). The trees at a rate of 1,173 gal/acre. Air sampling was respirator pad technique gave values that were ap­ carried out during the spraying operation and at proximately 3-5 times as great as those calculated 24-hour intervals for the next 3 days, then at 48- on the basis of the airborne samples. However, hour intervals for 6 days. A final air sample was Durham and Wolfe112 suggested that both collected 19 days after application. A breathing techniques provide the same value when the data zone sample taken during application analyzed at are adjusted to reflect their demonstrated ratio of 0.03 ppm (0.36 mg/m3) of parathion. On the fol­ impinged to inhaled toxicant. The results indicate lowing 3 days, the maximum airborne concentra­ the relative magnitudes of exposures during mix- tion found was 0.005 ppm (0.06 mg/m3). Seven ing-loading and application of parathion by the days after application, parathion could not be de­ dermal and the respiratory routes, and the need tected in the orchard air. for protective clothing and equipment. Batchelor and Walker106 analyzed air samples By sampling within a few feet of the spray from fruit orchards sprayed with parathion and operator’s breathing zone, airborne parathion con­ DDT at average single application rates of 1.8 and centrations ranging from 2.0 to 15.0 mg/m3 were 10.1 lb/acre, respectively. The material was ap­ measured by Kay and associates58 during the appli­ plied by either high-pressure hand spray equip­ cation of 15% wettable powder in the concentra­ ment, air-blast equipment, or aircraft. In addition, tion of 0.75 to 1.5 lb/100 gal of water and the authors determined airborne parathion concen­ dispersed at the rate of 300-400 gal/acre. High trations during pesticide mixing/loading of both concentrations occurred primarily when spraying the high-pressure hand sprayer and the air-blast during windy conditions. Workers exposed to these sprayer in a mixing plant and in a warehouse. The concentrations; of parathion experienced declines 37 in blood ChE activities. Air samples were also col­ rigs and compared it with that of spraymen using lected while workers added 15% parathion wetta- high-volume sprayers. Parathion was applied to ble powder to spray tanks. Parathion concentra­ fruit trees in the low-volume spray in 8-12 times tions derived from two tests in which the dust the concentration of the high-volume mixture cloud rose to the operator’s breathing zone were (0.24-0.36% vs 0.03% parathion). Both the poten­ 16 and 26 mg/m3. During the application of 0.75 tial dermal and respiratory exposures were calcu­ lb of 15% parathion wettable powder and 10 lb of lated by attaching absorbent cellulose pads to vari­ sulfur in 100 gal of water (a low-concentration ous parts of the worker’s body or clothing and by mixture) to apple trees, Kay et al58 measured 14.0 placing filter pads in special single- or double-unit mg/m3 of parathion in the breathing zone air of respirators designed to prevent direct impingement the operator. The following day, the airborne con­ of spray droplets onto the respirator pads. The centration of parathion was diminished to 0.09 total dermal exposure was calculated on the basis mg/m3 and approximately 3 weeks later it was of the exposed person wearing a short-sleeved, measured at 0.03 mg/m3. open-necked shirt, no gloves or hat, with his Jegier107 reported on the health hazards to trac­ clothing providing complete protection of the tor operators from insecticide spraying of crops. areas covered. Since drenching sprays can wet the Air samples were collected at the tractor opera­ worker’s clothing, dermal absorption can occur tors’ breathing zone and the results of the analyses through nonimpervious clothing; however, the for parathion were used to calculate respiratory dermal exposure values calculated by Wolfe et exposures. Filter pads attached to double-unit al109 on the basis of minimal protective clothing respirators and to the forehead and wrists of ob­ would tend to provide work practice recommenda­ servers riding beside the tractor drivers were used tions on the conservative side. The amount of to calculate respiratory (a second method) and parathion drawn into the respirator with sufficient dermal exposures. Parathion was applied to apples velocity to reach the absorbent pad was con­ as a spray in concentrations of 0.4-4.0 lb of 15% sidered to represent respiratory exposure. The cal­ wettable powder/100 gal of water. The air concen­ culated potential dermal exposure for operators of trations of parathion ranged from 0.05 to 0.26 low-volume spray equipment was 27.9 mg/hour as mg/m3 with a mean of 0.15 mg/m3 (10 samples). compared to 19.4 mg/hour with high-volume (ie, Jegier estimated a mean respiratory exposure of dilute spray) equipment. The authors109 attributed 0.03 mg/hour (range of 0.01-0.05 mg/hour) from the difference to an observed greater parathion analyses of the filter pads. Calculation of respirato­ contamination of the hands of the spraymen ry exposure based on the air sampling results and working with the low-volume spray. Potential res­ a lung ventilation rate of 444 liters/hour provided piratory exposure for low-volume spraying was an estimated respiratory exposure to parathion of 0.055 mg/hour, or about 2.7 times that estimated 0.07 mg/hour. The mean dermal exposure was for operators of conventional high-volume mach­ estimated at 2.4 mg/hour (range of 0.7-5.8 ines (0.020 mg/hour). mg/hour). Samples of spray mist were taken during and Using similar absorption pad techniques to mea­ after spraying operations with parathion in a sure the potential respiratory and dermal exposure study110 of orchard workers in Quebec. Parathion of workers spraying parathion on vegetable crops was applied as a spray (a fine mist) composed of with hand knapsack-misters, Simpson and Beck108 1.5-4 lb of 15% wettable powder/1,000 lb of water estimated the daily (8 hours) dermal and respira­ to apple trees. During the spraying operations, air tory exposures at 72.8 mg and 2.32 mg, respec­ samples were taken in the tractor-drivers’ tively. A study of the blood ChE activity of the breathing zones using fritted-glass bubblers con­ sprayers indicated that 30% of those tested had taining alcohol. Both air residual and leaf residue decreased levels. The investigators did not specify analyses were performed subsequent to applica­ what level of enzyme depression they regarded as tion. For sprays containing 3-4 lb of parathion significant; however, they stated that workers with 15% wettable powder/1,000 lb of water, applied at activities less than 60% of their preexposure values the rate of 0.12-0.15 lb (of 15% wettable powder) were removed from exposure. All samples col­ for each tree, average spray concentrations in the lected in the operator’s breathing zone by midget operators’ breathing zones ranged from 0.29 to impingers contained parathion in excess of 0.1 0.52 mg/m3 of air. Under near-windless conditions, mg/m3. the investigators found an airborne parathion con­ Wolfe et al109 studied the exposure to parathion centration of 0.12 mg/m3 in the orchard 1 hour of orchard spraymen operating low-volume spray after spraying. Parathion was not detected in the 38 orchard air after 1 hour of completing spraying in 112-113, and packed adsorbent columns, such as alu­ winds of 3-4 mph. mina.112,122 Nylon chiffon screens have also been Braid et al"1 assessed the potential exposure used.123 Each device has its advantages and disad­ from drifting parathion dust by taking samples of vantages, summarized by Miles et al118 as follows: the airborne dust and of vegetation at distances up . . packed columns are very efficient for to 400 feet from the dusting machine. One percent trapping vapors, but recovery of the sample is parathion dust was applied at a rate of 40 lb/acre frequently difficult; the filter systems permit the from a tractor-drawn duster which dispersed the collection of large volumes of air in short periods material at a height of approximately 2 feet above of time, but their efficiency for vapors is low and ground. The air was sampled at a height of 4 ft unknown losses of particulate and aerosol samples above ground, corresponding to the average occur during the sampling period; the scrubbers breathing zone height of people working in the are good for aerosols and vapors, but the sampling field, using electrostatic precipitators. Thirty-nine rate is slow and the use of sintered glass precludes cubic feet of air was sampled in each of five 13- the collection of particles; and cold traps are of minute dusting trials. Airborne dust loads were limited value iri field work in view of the main­ determined at distances of 50, 100, 200, 300, and tenance problem. Midget and Greenburg-Smith 400 feet from the application equipment. Average type impingers seem to offer a compromise in that wind speed during the 5 trials was 6.6 mph. The they can be operated at a reasonably fast rate, airborne parathion concentrations at downwind they are very efficient for collection of particulate distances of 50. 100, 200, 300, and 400 feet were matter, and with proper selection of solvent they 3.0. 0.85, 0.22, 0.07, and 0.03 mg/m'’1, respective­ can collect aerosols and vapors efficiently.” ly- Durham and Wolfe,112 in their review of sam­ From the results of these studies, it is evident pling methods for human respiratory exposure to that dermal exposure to parathion is significant pesticides, stated that the midget impinger has and actually constitutes a greater potential hazard been reported 1o duplicate “reasonably well” the than respiratory exposures in most occupational spectrum of particle sizes picked up by the nostrils situations. in breathing. They further stated that the Green­ General room ventilation is needed in parathion- burg-Smith impinger has the advantage of sam­ manufacturing and formulating areas. In addition, pling large volumes of air in a given time, thus im­ exhaust systems are needed at loaders, blenders, proving sensitivity where the concentration of mills, kettles, packaging equipment, and all other pesticide is low or the exposure time is brief. possible sources of vapor, spray, or dust containing Using a 4-hour sampling time for the Greenburg- parathion. Liquid and dust exhaust systems must Smith impinger, Miles et al118 reported a sensitivity be so designed that neither the workers nor other of 2.0 ng/m:! of parathion in air, or 1/25,000th the human and animal life in the surrounding area are airborne concentration permitted in the proposed at risk. Dust exhaust systems should be vented environmental standard. through a dust collector and organic vapor ab­ Because of the low air sampling rate inherent in sorber, so that air vented to the atmosphere is the midget impinger,117 sensitivity for similar sam­ adequately scrubbed.’* Detailed information on the pling times is less than for the Greenburg-Smith design and installation of exhaust systems for impinger though still very high. However, the size vapor and dusts of parathion should be sought of the midget impinger imparts greater adaptability from competent sources, such as ventilation en­ to the air sampling procedure without sacrificing gineers or industrial hygienists. precision. The midget impinger appears to be the Air Sampling Methods recommended collection device of choice for ob­ taining parathion-containing air samples. However, The sampling of air for parathion is complicated neither the sampling efficiency nor the overall by the fact that it may exist in vapor or particulate precision of the sampling and analytical method (ie, aerosolized liquid or dust) form. Thus sam­ are known. (RH Hill, Jr, written communication, pling devices must be versatile in their ability to March 1976) In addition, the Environmental Pro­ trap all the physical states of airborne parathion. tection Agency has withdrawn this sampling The most widely used pesticide air sampling method (ie, midget impinger using purified devices include: Greenburg-Smith or midget impin- ethylene glycol) from its pesticide sampling and gers5«,iofi. 10«,112-1ih bubblers or scrubbers (fritted analysis manual since “a controversy concerning glass absorbers)58’114-11*-119-120, glass fiber filters118,121 the reliability of the data” has arisen from using or cellulose filter pads10*1’11”' 112.113.118.12 0^ gauze pa(js the method. (RH Hill, Jr, written communication, 39 March 1976) Despite this, the impinger is technical parathion and formulations, it is applica­ presentl) the best available sampling device for ble to trace analysis where relatively high concen­ parathion in air. Since parathion may occur in air trations of PNP or the S-ethyl isomer of parathion as vapor, liquid droplets, or as an adsorbed film on ( 0,S-diethyl O-p-nitrophenyl phosphorothioate ) solid particles, it is essential that the impinger be are present. operated at a flow rate which will efficiently col­ Parathion, itself, has a moderate absorption lect all forms of airborne parathion. Appendix I maximum in the near ultraviolet spectrum at 274 gives details of the sampling and air flow calibra­ nm; Hirt and Gisclard11'1 utilized this property for tion procedures to be followed when using this direct analysis of the insecticide in air sampling method. Other air sampling methods which can be devices. The solution from a bubbler or midget shown to be equivalent, or superior, in efficiency impinger is diluted to a known volume, the ab­ to the impinger method may be used. sorbance of the parathion being measured spec- trophotometrically. Parathion Analysis Range and sensitivity of the spectrophotometric The first step in all the analytical methods con­ methods are limited by two factors, the ab­ sidered here is the removal of the pesticide and sorbance of the material analyzed and the sen­ other compounds of interest from the substrate or sitivity of the instrument used to perform the anal­ trapping medium. Filters and solid adsorbents are ysis. They also suffer from a variety of inter­ amenable to solvent extraction or desorption. The ferences. Many compounds absorb light in the extraction solvent must be compatible with sub­ near ultraviolet region, especially aromatic com­ sequent analytical procedures unless the solvent is pounds; therefore, the Hirt and Gisclard"6 method to be removed in the procedure. The contents of is especially susceptible to interferences. Com­ impingers or bubblers using nonvolatile solvents pounds that absorb in the visible spectrum are less must be partitioned into an immiscible, volatile common and would not normally be expected to solvent. For example, parathion collected in appear in air sampling devices and, as such, do not ethylene glycol is extracted from it with a light represent a problem in the Averell-Norris124 hydrocarbon, preferably hexane. method. However, aromatic nitro or amino com­ The variety of techniques available for assay of pounds can potentially behave like parathion by parathion-containing materials covers the gamut of forming a dye in the color development procedure, testing procedures from titration to the more com­ which may absorb at the same wavelength and plex instrumental methods. Several techniques are thus interfere. Isomers of parathion, its oxon, and applicable to the analysis of large amounts of p-nitrophenol are especially likely to give high parathion, such as are found in the technical parathion assays in the Averell-Norris method material or its formulations. Analysis of trace which is not specific for parathion. amounts of chemicals presents problems in sen­ Of the spectrophotometric methods, that of sitivity and specificity which can be overcome only Gage'2r> is the only one to have any specificity for with certain instrumental methods. The spec- any of the isomers of parathion; however, none of trophotometric methods can be used to analyze them estimates paraoxon separately from parathion directly or to assay it after derivatiza- parathion, it is either lost by hydrolysis or is read tion. as parathion. There is no UV-visible spec­ The residue method most commonly used before trophotometric scheme of analysis for the separate the development of a gas chromatographic detec­ determination (ie, limit of detection) of paraoxon tor specific for phosphorus was that of Averell and in the presence of parathion. Norris.124 In this method, the nitro group of the In 1964, the thermionic emission or alkali flame parathion is reduced to an amino group with zinc ionization detector (AF1D) was introduced by and hydrochloric acid. The amino group is then Giuffrida12,i; in 1966, Brody and Chaney127 in­ diazotized with nitrite and coupled with N-( 1 - troduced the flame photometric detector (FPD). naphthyO-ethylenediamine dihydrochloride. The Both detectors are modifications of the universal resulting dye has a deep magenta color, absorbing flame ionization detector and are highly specific at 555 nm. The light absorption of the colored for phosphorus. Since the development of the derivative is measured at 555 nm and is compared phosphorus-specific detectors, the preferred to a standard curve for quantitation. method for the analysis of parathion has been gas The spectrophotometric method of Ciage125 is a liquid chromatography (GLC) for the following modification of the Averell-Norris method. reasons: GLC offers the advantage over the spec­ Although it was developed as an assay method for trophotometric methods of superior specificity in 40 that it separates the components of the sample bility is another factor in precision. A dirty detec­ under scrutiny before the compound is quantitized; tor, especially with the AFID, a bad column, or a that is, the instrumental signal from the gas chro­ faulty electrometer or recorder will cause loss of matograph, as it is recorded, has a higher proba­ sensitivity and erratic responses. Overall precisions bility of arising from a true response to the com­ of±5% are not uncommon. Factors affecting accu­ pound being assayed than that from a spec­ racy are extraction efficiency, interferences, instru­ trophotometer. Thus, GLC offers simultaneous ment stability, and frequent use of standards. In­ qualitative and quantitative analysis. For parathion tegration of the areas of various peaks is a critical collected in air sampling devices, analysis should step in deriving numbers related to sample com­ be straightforward and should require no elaborate position; it is the conversion of the record cleanup steps.12” Analysis follows direct extraction produced by the detector from analog to digital of filters or vapor adsorbent and concentration of form. the extracting solvent to an appropriate volume. All the methods for estimation of parathion A pertinent problem in trace analysis of a pesti­ discussed in this document, photometric, spec- cide is the choice of a detector system. As men­ trophotometric, and GLC, quantitate their respon­ tioned above, two widely used phosphorus-specific ses to unknown quantities of the insecticide by detectors have been developed for pesticide comparing them with standard curves. The stan­ residue analysis, the FPD and the AFID.126,127 The dards used are originally weighed out and brought FPD has much less stringent requirements than the to known concentrations by serial dilutions and, as AFID for detector gas flow control and, thereby, such, are secondary gravimetric standards. Thus, requires less time for maintenance and adjustment all the methods yield values that are in units of of the detector. The FPD also maintains a more weight of parathion, so that the estimates obtained stable response during a period of time than the by different methods are comparable directly. AFID and requires less frequent injection of stan­ Air monitoring should produce samples relative­ dards for proper calibration. In addition, the AFID ly free of interferences when analyzed with a gas is responsive to organic compounds containing chromatograph equipped with a specific detector chlorine, nitrogen, and sometimes sulfur, though to of phosphorus. Any organophosphorus compound a lesser degree than to phosphorus when the in­ that survives pyrolysis will be detected, but only strument is tuned properly. Therefore, the FPD is those having a retention time close to that of considered to be superior to AFID. parathion will interfere. Large quantities of or­ Great sensitivity is also a major advantage of the ganic material will increase background noise for GLC-phosphorus specific detector method of anal­ the FPD, thereby reducing the accuracy of the ysis. Averell and Norris124 reported that 20 /xg of method. In summary, GLC with FPD offers the parathion in the final 50-ml aliquot represented following advantages over the photometric and the sensitivity of their method. Because of great spectrophotometric methods: differences in extinction coefficients, the Averell- ( 1 ) Less subject to interferences from con­ Norris method is inherently a thousand times more taminants. sensitive than the method of Hirt and Gisclard.116 (2) Specific for parathion. In contrast, Guiffrida126 detected 0.024 ¡ig of (3) Greater sensitivity. parathion using GLC with AFID. For normal (4) Greater precision and accuracy. The analytical work, a convenient working range for GLC with FPD method is therefore recommended. AFID i's between 50-1,000 picograms (pg)/injection volume. GLC with FPD was re­ Plasma and RBC ChE Analysis ported127 to be sensitive to 250 pg of parathion As the identification of the various ChE en­ using a 526-nm filter; the response was linear from zymes developed, the determination of the cata­ 6 ppb to 60 ppm. lytic ability of enzymes in tissue by various The precision of GLC analysis depends largely methods was performed to determine the effects of on several factors. Syringe-handling technique is various inhibitors on tissue enzyme activities. very important for the small volumes of samples The early methods of determination of ChE ac­ used with the phosphorus-specific detectors. Injec­ tivities used principally acetylcholine as a substrate tions are commonly made against 20-40 psi of car­ and measured the release of H-ions as the esters rier gas pressure, and a worn syringe or injection- were hydrolyzed. This change has been measured port septum can cause serious sample loss. Use of manometrically,129,1:10 by change in an acid-base in­ a solvent-flush technique usually increases the dicator,131,132 and by electrometric pH measure­ reproducibility of sample analyses. Instrument sta­ ment.133 41 Manometric methods for analysis of ChE’s have tory variation. The pH-stat method employs a been found to be among the most precise but have titration at constant pH. Although the activity of the inherent drawbacks of time-consuming ChE enzymes has been observed to be pH-depen- manipulations and procedures. These methods dent, the small change in pH observed in the ApH have been used for both RBC and plasma ChE as­ methods has a comparatively small and correctible says.134'136 effect on the activity of ChE. Thus, the pH-stat Methods using a change of indicator color have method does not have a significant advantage in been successfully used with serum ChE samples,112 this regard; it does have the advantage that a 5- but are not applicable to hemolyzed RBC samples minute titration is usually sufficient for estimating or plasma because of the turbidity of such solu­ the ChE activity of a sample. Furthermore, normal tions. Unless dialysis membranes are used,137 the human values are less well established with this analytical precision decreases because of the tur­ method than with that of Michel.134154 bidity.|:,2-13K The principle of this method has led to Other methods have been used to determine the several useful field screening methods. Such field rate of hydrolysis of various substrates by enzyme- methods have poor precision, ±25%, but this containing biologic samples. This has been done degree of precision is not inappropriate for screen­ by estimating the amount of unreacted ACh after ing methods.137144 a period of incubation with a source of ChE155157 The electrometric method of Michel133 was and by measuring the release of thiocholine from developed primarily to decrease the time required acetylthiocholine by ChE’s.158, ,59-16°.161 The for analysis and has been found to be well-suited methods for the determination of unreacted ACh for determinations of both RBC and plasma ChE have been used primarily with serum samples and activities. This method has been widely used in the have not been used frequently in this determina­ measurement of RBC and plasma ChE in men ex­ tion after OP exposures. The method of Hestrin, posed to OP ChE-inhibitors. In fact, the ApH which appears to be the standard method for method has been the one used in most of the re­ serum ChE,162,163 has been used in establishing nor­ ported determinations of normal human RBC and mal values,154 and has precision comparable with plasma ChE values.134 Additionally, the best the ApH method.136 The method has apparently established normal values for humans were deter­ not been used for determining ChE in plasma or mined145 using the original ApH method of RBC’s, presumably because of the turbidity of Michel.133 The studies by Vorhaus and Kark146 of such solutions. The method can be used under a changes in serum ChE activities due to disease great variety of experimental conditions, however, also used the original ApH method of Michel. including wide ranges of pH’s, substrate concentra­ Variations of the original Michel method have tions, enzyme concentrations, and buffer solu­ been proposed to make the method more con­ tions.136 A method which can accommodate varia­ venient. Procedures have been proposed using ble conditions does not necessarily gain an ad­ capillary blood sampling methods rather than vantage from this fact, however, because such those involving venipuncture,147 automated variations usually are not encountered in the rou­ systems,148 less analysis time,149 and a single mea­ tine analysis of human ChE’s. surement of pH 150 The method of Wolfsie and The methods which estimate ChE by determin­ Winter147 has the advantage of not requiring sam­ ing the amount of hydrolyzed acetylthiocholine ples as large as those of the original Michel have been used for several years since they were method, without any apparent loss of precision.151 first developed by Koelle and Friedenwald159 for The production of acid has also been monitored histochemical determinations. Methods have been by continuously adding base to maintain a con­ developed using several reagents which form stant pH as hydrolysis occurs. Such methods are colors with the thiocholine present after hydrolysis referred to as PH -stat methods.152,153 The pH -stat of acetylthiocholine.1581“1164 Determinations of methods have not been reported in surveys and ChE’s in plasma, serum, RBC’s, and other tissues case studies of OP poisoning as often as the ApH were possible using the method of Ellman et al,164 methods. Equipment required is more difficult to but there are possibilities of interferences by icter­ operate and maintain than the relatively simple ic or hemolytic plasma. This method has been equipment of the ApH methods. The pH-stat adapted for use with an automatic analyzer and is method was found by Crane et al151 to be less thus useful-for the routine analysis of large num­ precise (1.70% relative standard deviation) than bers of samples. Normal activities of human ChE’s the ApH method (1.45% relative standard devia­ with these methods have not been reported exten­ tion), and to exhibit a high degree of interlabora­ sively.134 The precision of these colorimetric 42 methods is not as great as that of the ApH Clearly, there is much overlap of the distributions methods,164,185 and there are some additional of normal ChE activities in the two studies, and characteristics which may detract from their suita­ the difference in means should not be given undue bility for routine analysis. Among these are the significance in these comparatively small samplings fact that the substrate concentration is too low for from the entire population. the determination of plasma ChE,1*5 and that auto­ The standard deviations for chemical analyses of oxidation of thiocholine is possible165; there is also ChE’s by the methods of Wolfsie and Winter147 some disagreement over the relative specificities of and Rider et al,145 0.03 ApH/hr, are small in com­ acetylcholine and acetylthiocholine.159,lfi0,l(!4 parison to the interindividual variations ob­ Several other laboratory methods have been served.145 They are included in the overall stan­ devised, such as the amperometric method dard deviation reported. described by Einsel et al1'* and the radioassay The means of the normal populations by these methods of Winteringham and Disney,lfi7,lwi and two “ApH” methods145,147 are closer for plasma Potter.1® A gas chromatographic method was ChE activity than for RBC ChE activity. The developed by Cranmer and Peoples170 and an means of the plasma ChE activities of the 2 groups acetylcholine-ion-selective electrode was of normal subjects were found by Wolfsie and developed by Baum.171 These alternate methods Winter 147 and Rider et al145 to be 0.912 and 0.95 3 have not received widespread acceptance and have ApH/hr, respectively, and the standard deviations not been well documented in the open literature. were 0.11 and 0.19, respectively. The ranges for The principal reasons are that these methods plasma ChE in normal humans of Wolfsie and require more expertise than the colorimetric and Winter and Rider et al were 0.408-1.652 ApH/hr ApH methods. Equipment used in these methods is and 0.52-1.39 ApH/hr, respectively, indicating more specialized and expensive than that used in again that the group of normal subjects used by manual colorimetric and ApH methods. A com­ Rider et al had plasma ChE activities included parison of normal values of activity for RBC ChE within the range determined by Wolfsie and in humans by the Wolfsie and Winter147 method Winter. and the original method of Michel used by Rider Based upon the consideration of means, stan­ et al,145 shows similar values for mean activity of dard deviations, and ranges, the conclusion can be RBC ChE. Wolfsie and Winter147 found a mean of made with a high degree of reliability that there is 0.861 ApH/hour with a standard deviation of not an appreciable difference in either the normal 0.091. Rider et al145 found a mean of 0.766 values determined in the 2 studies or the analytical ApH/hour with a standard deviation of 0.081. methods used in them. Rider et al explained the difference between the In studies of serum ChE activities in various mean RBC ChE activity that they determined and groups, different normal values have been found that of Wolfsie and Winter on the basis of proba­ for men and women.154 In the largest study re­ ble contamination of red cells by plasma in the last ported,145 the mean of the female plasma ChE was two authors’ work, since the RBC’s were not found to be lower than the plasma ChE of men. washed during that study. Witter1® suggested that The female/male ratio of 0.86 found by Rider et the difference may have been due to increased al145 was representative of those found in several packing of RBC's in the Wolfsie and Winter study. other studies reported by Wetstone and LaMot- Also, this difference in means may be due, in part, ta.154 to the fact that the same persons were not tested Based on the foregoing, the biochemical assay in the two studies. In establishing their mean, method of Michel1“ has been selected as the Rider et al145 sampled 400 men, whereas Wolfsie method of analysis to be recommended because it and Winter sampled 255 men. The two groups of has been the most popular, is the most widely subjects were small enough to allow the discrepan­ documented, and is unsurpassed in precision. The cy in mean values without necessarily concluding laboratory equipment necessary is standard, rela­ that the RBC’s were contaminated, especially in tively inexpensive, and simple to use. Although the view of the ranges and standard deviations in the method is not automated, it does provide small studies. The ranges determined by Wolfsie and laboratories with the capability to analyze many Winter and by Rider et al were 0.554-1.252 samples without excessive expense. Normal values ApH/hr and 0.58-0.95 ApH/hr, respectively. The using this method are based upon the largest ex­ range of ChE activities of the group of subjects tant survey of a nonexposed population. (Table studied by Rider and his associates fell within the XI-2) The micromodification of the sampling range for the group of Wolfsie and Winter. method used in the original Michel method, 43 described by Wolfsie and Winter,147 used in con­ junction with the original biochemical assay method of Michel will provide sufficient precision in analysis without excessively great bloodletting.H8-172

44 V. DEVELOPMENT OF STANDARD

Basis for Previous Standards Parathion appeared in both the tentative A federal ambient air (ie, workplace) standard Threshold Limit Value and established value lists for parathion of 0.1 mg/m3, with a warning con­ of the American Conference of Governmental In­ cerning skin absorption, has been promulgated by dustrial Hygienists (ACGIH) in 1954,173 with a the Occupational Safety and Health Administra­ suggested TLV of 0.1 mg/m’1. tion under the authority of the Occupational Documentation for the ACGIH value174 was Safety and Health Act of 1970 (29 CFR Part published in 1962. The TLV of 0.1 mg/m1 was 1910.93 published in the Federal Register primarily based on conclusions drawn from the 39:23542, June 27, 1974). This standard is based studies of Kay et al58 and Brown and Bush.79 Kay upon the recommendation of the ACGIH. The use et al5h measured airborne parathion levels ranging of the word skin following parathion in the federal from 2 to 15 mg/nr1 in the breathing zones of wor­ standard is intended to suggest appropriate mea­ kers engaged in orchard spraying. At the end of a sures for the prevention of cutaneous absorption 2-month spraying period, during which time the so that the ambient air limit is not invalidated. workers were intermittently exposed, the blood There are no state environmental limits more ChE levels of the sprayers were decreased about restrictive than the federal. 25% below control values. The average daily expo­ Permissible levels of toxic substances in the sure was estimated174 by the Committee on work environment for a number of countries in ad­ Threshold Limit Values to be not more than 2.0 dition to the US have been published by the Joint mg/nr1 even though the range of measured air­ ILO/WHO Committee tin Occupational Health.177 borne parathion levels was 2-15 mg/m3. Brown and Finland, the Federal Republic of Germany, Japan, Bush79 measured airborne parathion levels ranging Rumania, and Yugoslavia all have occupational ex­ from 0.1 to 0.8 mg/m:i in a manufactur­ posure standards of 0.1 mg/nr1, while Bulgaria, ing/formulating plant in which workers showed Hungary, and the USSR adopted 0.05 mg/m3 as a decreased RBC and plasma ChE activities. The maximal acceptable concentration (MAC). In the TLV documentation states,174 “Based on these cal­ USSR, MAC’s are defined as . . absolute culations, 2 mg/m3 would appear to be an exces­ limits that should not be exceeded during any part sive exposure. From the work of Brown and Bush, of the working day, regardless of lower concentra­ 0.5 mg appears excessive. It is concluded that the tions that may have existed during any of its figure of 0.1 mg/m3 provides the best estimate for period. They are set at a value which will not a threshold limit from available data.” produce, in any of the persons exposed, any devia­ In the 1966 Documentation of Threshold Limit tion from normal, or any disease which can be de­ Values,175 the results of various animal feeding stu­ tected by the most modern research methods dies were reported. In addition, the results of available.”177 Smelyanskiy and Ulanova,178 in a Edson’s study35 involving the daily oral ingestion of paper dealing with Russian MAC’s, stated that parathion by human volunteers were presented; methods for investigating CNS function and higher “doses of 1.47 mg/man/day produced no effect in nervous activity, biochemical and delicate volunteers, while a dosage of 5.46 produced morphologic and histologic techniques, and the moderate depression of blood cholinesterase.”175 use of both conditioned and unconditioned The TLV' was believed to be sufficiently low to reflexes, among others, are of value in detecting prevent significant depression of blood ChE activi­ early manifestations of chronic toxicity of work­ ty provided that contamiantion of the skin was place substances. prevented. The data of Arterberry et al50 showing a slight Basis for the Recommended Environmental depression in blood ChE activity at a urinary PNP Standard excretion of about 2 mg/liter in workers repeatedly The characteristic signs and symptoms of exposed to parathion was included in the Third parathion poisoning, discussed in Chapter III and Edition (1971) of the Documentation of the listed in Table III-1, are due to cholinergic stimula­ Threshold Limit Values.176 The recommended tion resulting from inhibition of the activity of TLV' remained at 0.1 mg/m3. neuroeffector and other tissue ChE’s.1 There is 45 evidence from experiments with DFP71 that RBC produce the same effects, with further depression and plasma ChE’s serve as “buffers" protecting in blood ChE’s and urinary excretion of PNP. the more vital tissue ChE’s from inhibition. Karcz- Thus, the likelihood of detecting continuing mar and Koppanvi71 demonstrated in animals with parathion absorption with resultant ChF. depres­ a normal amount of neuroeffector ChE that sion through a routine biologic monitoring pro­ lowered activities of plasma and RBC ChE’s in­ gram is gieater by estimation of blood ChE’s than creased responses to ACh, BC'h. and DFP. They of urinary p NP. Cholinesterase activity levels ap­ were able to demonstrate also that, in animals in pear to be netter indicators of OP exposure since which the tissue ChE’s had been reduced to near the regeneration/replacement rates are slow zero, the infusion of ChE-rich blood probably did enough18 to integrate the exposure effectively and not restore activity at the neuroeffector sites. In allow practical sampling frequencies. In addition, such animals, however, responsiveness to injected workers engaged in formulation, mixing, and appli­ ACh was nearly the same as that of control cation of parathion arc likely to be simultaneously animals. exposed to other ChE-inhibiting insecticides, such The absorption and subsequent metabolic con­ as mevinphos, , TFPP, azinphos- version23'25 of parathion by the body reduce the methyl, and ofhers, which do not result in urinary ChE activities in central, peripheral, and au­ excretion of PNP. In cases of exposure to mixed tonomic nerve tissues, RBC’s. and blood plasma.18 anticholinesterase pesticides, urinary monitoring of Grob et al18 demonstrated that the blood ChE’s PNP levels would not necessarily provide warning are depressed along with tissue ChE’s in humans of additional inhibition of blood ChE’s. Workers poisoned by parathion. Other investigators have exposed to parathion alone are the exception shown8,!M1,13- significant depressions of rather than the rule. both RBC and plasma ChE’s in workers exposed The metabolism and hydrolysis of OP pesticides to parathion but not exhibiting signs and symptoms in mammals result in the excretion in urine of a of parathion poisoning as well as in those exposed variety of alkyl phosphates.181182 Shafik et al182 fed and exhibiting signs and symptoms of poisoning. parathion to rats at 1/10 the LD50 for this species In addition to blood ChE determinations, esti­ and recovered both 0,0-diethyl phosphate (DEP) mation of metabolites such as urinary PNP as a and O.O-diethyl thiophosphate (DETP) in the measure of human exposure to parathion has been urine. The total DEP and DETP excreted in the proposed.37'4B'5I,10‘ I7!' Determinations of blood and urine accounted for 30-40% of the parathion ini­ urine alkyl phosphates have been suggested tially fed. Their results suggested that the DEP also.1"0'1*2 In 1970, Wolfe et al51 reported that PNP arose from the action of hydrolytic enzyme(s) on excretion levels correlated well with exposure to paraoxon, a metabolite of parathion. Excretion of parathion. The average peak excretion level oc­ these metabolites remained relatively constant dur­ curred 8.7 hours after exposure; the levels of PNP ing exposure and dropped rapidly to zero upon were insignificant 48 hours after exposure. Thus, it cessation of feeding. Blood and urine alkyl is important to obtain urine samples soon after ex­ phosphate (ie, phosphates, thiophosphates, and posure. Arterberry et al50 concluded in 1961 that dithiophosphates) determinations are presently un­ PNP excretion is not a reliable measure of the dergoing additional research and evaluation; they severity of poisoning. In agreeing with the conclu­ show great promise for the future as diagnostic sion of Arterberry et al, Wolfe et al51 stated that procedures. PNP was a more sensitive measure of exposure Electromyography (EMG)li7,,i8 has been used to than were blood cholinesterase levels though the measure the effects of mixed pesticide exposure latter seemed to correlate better with occurrence (organochlorine and organophosphorus pesticides) of poisoning than did PNP excretion. As a on the neuromuscular system. No studies showing hypothetical example, following an exposure to altered electromyographic response in workers ex­ parathion sufficient to depress the RBC and posed to parathion alone have been published. plasma ChE’s to 60% of their preexposure values, Neither the alkyl phosphate metabolite method PNP will be excreted in the urine. In order to nor the EMG technique is currently acceptable determine the extent of this exposure, the urine since the test results cannot be satisfactorily quan­ would have to be collected within approximately 9 titatively related to either the extent of exposure hours of exposure.51 About 2 days later, the urina­ or the hazard to the worker. ry PNP excretion would have ended51 whereas the Thus, because RBC ChE activity levels provide blood ChE’s would still be depressed from nor­ an acceptable means of correlating the extent of mal.18 Subsequent significant exposures would exposure with the immediate effect, and because 46 these levels are relevant to mixtures of ChE-in- have been reported72'74 to be depressed in persons hibiting pesticides and allow for practical sampling afflicted with liver disease, anemia, acute infec­ frequencies, routine biologic monitoring of the tious and chronic debilitating diseases, and mal­ RBC ChE and monitoring of both RBC and nutrition. Drugs such as and related plasma ChE’s in emergency exposure situations are xanthine compounds,183 chloroquine and other an- recommended for the prevention of adverse health timalarial drugs,™ chloroform,184 ether,184 narcotic consequences in parathion-exposed workers. analgesics such as morphine and codeine,77 and There are daily variations, both in the plasma thiamine185 have been shown to depress the activi­ and RBC ChE activities of normal, healthy persons ty of serum ChE. A few drugs have been reported who are unexposed to ChE-inhibiting OP pesti­ to depress RBC ChE activity, including quinine,7H cides, including parathion.181'1’1 ^,172 Fryer et al172 other antimalarial drugs,7*’ and .1W1 determined the probable daily variations of plasma Fryer et al,7;! analyzed the day-to-day variations and RBC ChE activities for a normal, healthy in­ in the ChE’s of the blood of 17 unexposed sub­ dividual using a micromodification of the Michel jects during 5 days and concluded that 95% of method. In this study of 17 volunteers from a normal people would have day-to-day variations of university staff with no known exposure to OP in­ not more than 0.171 ApH/hr in RBC ChE and not secticides, the normal daily variation from the more than 0.351 ApH/hr in plasma ChE. Applying group mean in both plasma and RBC ChE’s was these criteria to a group of 89 agricultural workers determined. Five consecutive daily samples were who had not knowingly been exposed to OP com­ taken from each volunteer except one; in that pounds for at least three months, they found, with case, there was a one-day gap in the series. For 95% confidence, that there were 3 true positive re­ RBC ChE activity, the range was ¿23% from the ports, 12 false positive reports, and no false nega­ group mean; for plasma, the range was±37%. The tive reports of decreased RBC ChE, and one false day-to-day variation within individuals for RBC negative report and no positive report of decrease and plasma ChE activities was ±5% and +9%, plasma ChE. The authors pointed out that a respectively, for the group as a whole. Individual knowledge of preexposure ChE activities is neces­ maximal variations were+13% and±23% for RBC sary for any degree of accuracy in determining and plasma ChE activities, respectively. The whether a particular individual’s ChE’s have been authors172 did not indicate race, age, or sex dif­ altered, but that their tolerance limits may be use­ ferences in the volunteer group. It must be noted, ful in interpreting measurements of ChE activities however, that any extrapolation of these data to a in blood samples submitted at random from the larger group must consider the possible changes in field. variation that may occur because of these factors. The two populations differed somewhat in mean Rider et al145 have shown that the plasma ChE age: 30 years for the unexposed group and 38 levels are higher in men than in women and in­ years for the group of agricultural workers. Fryer crease slightly with age. In men, the increase was et al did not give any further identification of the 0.002 ± 0.001 ApH/hour/year of age and twice that test populations by sex or race or give any indica­ in women. The authors did not Find significant dif­ tion of other possible exposures that might have ferences in RBC ChE with age or sex. On the affected blood ChE levels except that they ruled other hand, Vorhaus and Kark14,i could not find a out recent known exposure to OP insecticides. difference in plasma enzyme activity that could be The most striking, and perhaps the most signifi­ correlated with age, sex, weight, or height. They cant, difference between the handling of the blood did not evaluate differences in RBC ChE. samples from the two groups was that those from Reinhold et al13H also found plasma ChE activity the agricultural workers were not refrigerated for higher in men than in women. They noted also dif­ about 6 hours after their collection and during that ferences between blacks and whites in both men time were subjected to some agitation. The finding and women. The group mean of 0.926 for the that the unexposed individuals had a higher mean serum ChE activity of white men was significantly RCB ChE activity and a lower mean plasma ChE higher than the observed group means of 0.814 activity than the agricultural workers could mean and 0.768 for black men and women, respectively. that their blood samples underwent slight hemoly­ In this study, 130 white men, 46 black men, 70 sis during transport to the laboratory. Such an ef­ white women, and 28 black women were com­ fect could contribute to the false negative reports pared. of decreased RBC ChE but would not increase the In addition to changes in blood ChE activities ChE activity of the plasma sufficiently to explain due to sex, race, and age, serum ChE activities the excess activity there in the group of agricul­ 47 tural workers. Some other factor seems to be in­ ing/formulating plant resulted in average depres­ volved, therefore, in generating the differences sions of plasma of 34% and RBC ChE activities of between the two groups. 61%, without the appearance of signs and symp­ Even though the effect of these limitations can­ toms of poisoning. not be assessed, the estimates by Fryer et al172 of Rider et al14 observed depressions in plasma normal daily variations in plasma (9%) and RBC ChE-. of 50%, 52%, and 54% in 3 subjects receiving (5%) ChE activities among individuals are in ap­ daily oral doses of 7.5 mg parathion for approxi­ proximate agreement with those determined by mately 30 days without signs and symptoms of Callaway et alIS5 and Wetstone and LaMotta.1’4 poisoning. In these same individuals, the lowest Callaway et al1:l5 found that the daily variations in RBC ChE activity levels observed during the study the plasma and RBC ChE activities of normal, were 63%, 78%, and 86%: of pretest levels (ie, healthv men were 8.5% and 6.6%, respectively. depressions of 14-37%). Wetstone and LaMotta151 reported that the overall In 4 female volunteers receiving 7.2 mg intra-individual variation in serum ChE activity for parathion/day orally, the plasma and RBC ChE ac­ 82 subjects tested 373 times during a 1- to 250- tivities declined to 84% and 63%, respectively, of week interval was 8.4%. In 1975, Sidell and control activity after 6 weeks of exposure.'15 Kaminskis187 reported on the temporal variability Neither signs nor symptoms of poisoning occurred of human ChE. Twenty-two subjects were studied in these subjects. during a 1-year period. The coefficients of varia­ Hartwell and associates'17 observed no signs or tion for plasma ChE activity were reported to be symptoms of poisoning in a volunteer exposed for about 6% for both males and females. In agree­ 30-minute periods on each of 4 consecutive days ment with previous investigators, the authors to vapors of heated parathion when the RBC and found that the activity of the RBC ChE was more plasma ChEi activities were depressed 30% and constant, the average coefficient of variation was 53%, respectively. However, signs of parathion 2.1% for males and 3.1% for females. poisoning appeared in the subject 10 minutes after Based on the aforementioned experimental the parathion was mistakenly heated to 150 F; a evidence, depressions in plasma and RBC ChE ac­ subsequent determination of blood ChE activity tivities less than 369; and 22%, respectively, from levels indicated that RBC and plasma ChE were mean normal values can be due to normal daily depressed 98% and 83%. respectively. variations. Another important consideration in Plasma and RBC ChE activity levels were selecting a particular percentage level of blood depressed 98.6% and 93.3% respectively, from ChE depression for both worker prolection and normal, iri a 15-year-old girl suffering from compliance purposes is the correlation between parathion poisoning.52 Prior to blood ChE activity blood ChE activity depression and the appearance determinations, she exhibited the following signs of of signs and symptoms of parathion poisoning. The parathion poisoning: shallow and irregular respira­ level of depression to be tolerated must be such tion, constricted pupils, low systolic blood pres­ that it will demonstrate that an exposure to sure, inspiratory rales in all lung fields, muscle parathion has occurred before the worker actually lasciculations in the limbs, and bronchopharyngeal becomes ill and allows immediate steps to be secretions, among others. taken to correct the situation leading to the expo­ Grob et al18 studied the effects of parathion on sure. It is important also that the worker not be 40 men and women who had been exposed to the removed from his job unnecessarily, so that a compound on one or more days during the month warning level of RBC ChE depression and an ac­ preceding the appearance of symptoms. Only 5 of tion level, at which the worker must be removed the 40 (12.5%) poisoned individuals experienced from potential exposure, seem desirable. any “warning” symptoms, including intermittent In general, the literature indicates11-18"""1'’’' nausea, vomiting, giddiness, weakness, drowsiness, :i7,:w,5-j.7!» normally only at depressions ofand twitching of the eyelids, prior to the day on plasma and RBC ChE activities considerably which severe signs and symptoms appeared. The greater than 30% do signs and symptoms of average period of exposure was 8 hours/day for 1 2 systemic parathion poisoning appear in individuals. days. Six men died, 2 men and 2 women ex­ Certain degrees of depression of blood ChE activi­ perienced severe but not fatal symptoms, and 24 ties are not accompanied by a significant men and 6 women had mild to moderate symp­ prevalence of local or systemic effects. toms. Four patients who survived despite severe In the study by Brown and Bush,79 exposure to symptoms and 2 who died had plasma and RBC parathion of 5 of 12 workers in a manufactur­ ChE depressions (compared to normal values) of 95% or greater and 78-89% (average 86%), plasma ChE is inhibited more promptly and to a respectively. These values averaged 90% and 78%, greater extent than the RBC enzyme in individuals respectively, in 6 other subjects with symptoms of initially exposed to parathion. The rate of return moderate degree. of inhibited plasma ChE exceeds that of the RBC Hartwell and Hayes:i8 reported the case of a enzyme so that, during a period of consistent but pilot who became ill with mild poisoning after ap­ moderate exposure, the ChE activity of plasma plying both dust and liquid forms of parathion in­ may actually be greater than that of the RBC’s. 18 termittently for severals days; his RBC and plasma Grob et al,18 in their study of 18 workers poisoned ChE activities were depressed 48% and 44%> from by parathion found that plasma ChE increased at normal, respectively, measured on the day of onset an average rate of approximately 9% of normal ac­ of illness. RBC and plasma ChE activities were tivity during each of the first 3 days following ter­ depressed 34% and 28%, respectively, in a second mination of exposure, while the RBC ChE activity pilot engaged in crop-dusting who complained of increased at an average daily rate of approximately excessive sweating and a mildly upset stomach. 3%. However, averaged over the entire period of In a group of 4 workers exposed to parathion recovery, the rates of return approximated 1 - residues during apple thinning, in whom signs and 2%/day and 3-4%/day for RBC and plasma ChE’s, symptoms of parathion poisoning occurred, RBC respectively. Thus, under certain exposure situa­ and plasma ChE activity depressions ranged from tions, the plasma ChE activity could return to nor­ 61-66% and 71-83%, respectively.11 The enzyme mal while the RBC ChE activity remained activities were measured by the Michel method 2 depressed. For this reason, it is more likely that days following the onset of symptoms (percentexcessive absorption of parathion resulting from depressions were calculated using the mean values relatively low-level repeated exposure can be de­ for the Michel method determined by Rider et tected by routinely monitoring for RBC ChE ac­ al).145 Nausea, vomiting, sweating, weakness, short­ tivity. In addition, the plasma enzyme is subject to ness of breath, headache, giddiness, and twitching greater normal daily variation than the RBC ChE, of the eyelids were seen in these workers. approximately 9% versus 5%, respectively.172 Important conclusions can be evolved from the Previously, we have pointed out that the plasma preceding discussion: ( 1) there may be day-to-day ChE can be lowered in individuals with liver dis­ variations in both the RBC and plasma ChE’s of ease, anemia, debilitating disease, or malnutrition; normal, healthy individuals,58 135154-172 and (2) signs drugs such as quinine,711 morphine, and codeine77 and symptoms of chronic systemic parathion also depress the plasma ChE activity. Thus, moni­ poisoning usually do not appear in humans until toring plasma ChE activity increases the likelihood these enzyme activities are depressed by about of false positive results. On the other hand, the 50% below normal levels.n’18-34’35, ■17-38-52'79 Even RBC ChE has not been shown to be affected by greater depressions of the ChE’s of the blood may such diseases; a depression in the RBC ChE activi­ be incurred without the appearance of signs or ty exceeding normal variation in parathion-ex- symptoms of poisoning by parathion. posed workers is almost certainly due to the ef­ In many cases, individual worker preexposure fects of the insecticide. A similar reduction in the blood ChE activity values will not be available, activity of the plasma enzyme is considerably less thereby necessitating the use of mean values deter­ certain to be clue to exposure to parathion. There­ mined for normal populations. Because of the fact fore, routine monitoring of RBC ChE will provide that both the individual preexposure and group a better estimate of exposure to parathion. How­ mean activity levels will be used as the situation ever, an RBC ChE monitoring program based on a warrants, it would be arbitrary to set an allowable preset sampling frequency should be effective in level of blood ChE depression based solely on the detecting the slow development of systemic variation calculated for 95% of the population at a parathion poisoning due to progressive inhibition 95% confidence level, namely, approximately 22% of the activity of AChE at various sites throughout and 36% for RBC and plasma ChE, respectively. the body; it is intended to warn of excessive Therefore, in the case of RBC ChE, a depression parathion absorption in a situation involving long­ exceeding 30% of the worker’s baseline value will term, low-level exposure. Routine RBC ChE moni­ be considered as indicating excessive exposure to toring will not, in all likelihood, provide a warning parathion. Only the RBC ChE is recommended for of impending poisoning from massive exposures, routine monitoring for the following reasons. resulting in precipitous declines in both the blood Although the results of studies18,34,81,103 involving and tissue ChE’s, such as in the case of inhalation animals and human volunteers have shown that exposure to high concentrations of parathion dust or aerosol or dermal exposure to spills, sprays, or in industry in which both air samples indicating splashes of concentrated material on the skin or significant exposure and RBC and plasma ChE clothing. Also, since relatively nonsevere signs and monitoring showing biologic response were ob­ symptoms of cholinergic stimulation can occur as tained is the often-cited work of Brown and the result of localized effects of parathion expo­ Bush.79 Thirteen workers in a plant manufacturing sure, a biologic monitoring program based on the concentrated parathion and dusts of varying con­ activity levels of the blood ChE’s may not prevent centration were studied. Twelve of the 13 workers or warn of the development of such signs and were exposed to airborne concentrations of symptoms under certain exposure conditions. For parathion ranging from 0.1 to 0.8 mg/m3 (0.1 example, miosis and blurred vision can result from mg/m3 being the lower limit of detectability) as direct exposure of the eyes to parathion, local determined using sintered glass absorbers, midget fasciculations can occur in the immediate area of impingers, and Greenburg-Smith impingers. Six absorption of parathion from the surface of the general location and 6 worker breathing zone air skin, and bronchial secretions can result from samples were collected. The average airborne respiratory exposure, all in the absence of signifi­ parathion concentration for 8 sampling sites was cant effects on the blood ChE’s. Good work prac­ 0.2-0.3 mg/nv1. Because of rotation of plant per­ tices and the use of personal protective clothing sonnel, the workers were only intermittently in and equipment will best serve to protect workers contact with parathion-contaminated air. Both from such effects, particularly those resulting from plasma and RBC ChE activity levels were deter­ accidental spills, sprays, or splashes. Also, since mined during a 10-month period; however, preex­ the plasma ChE is inhibited more readily than the posure control values had been obtained for only 6 RBC ChE1"34,87,103 under acute exposure condi­ of the 12 parathion-exposed workers. A maximum tions, the plasma ChE activity may decline of 3 blood samples was collected during a 5-month precipitously in massive exposure situations while exposure period; control values for the other ex­ the RBC enzyme at first is relatively uninhibited. posed workers were determined from blood sam­ Therefore, in cases of known or suspected ples collected 5 months after the end of exposure. parathion overexposure (ie, exposure to either air­ Five of the 6 workers with preexposure ChE ac­ borne concentrations exceeding the environmental tivities experienced the following depression of limit or to spills or splashes, etc), both the RBC plasma and RBC ChE activities, respectively: 22% and plasma ChE activities should be determined. and 73%, 7% and 42%., 46% and 63%, 52% and Kay et al5K demonstrated that workers engaged 60%, 41% and 66%. The reductions in plasma and intermittently in the ground spraying of parathion RBC ChE activities averaged 34% and 61%, experienced significant seasonal declines in blood respectively. An engineer in the plant, the sixth ChE activities. They found no significant dif­ worker for whom baseline blood ChE values were ference in the RBC ChE activity levels between available, experienced no significant decline in sprayers reporting symptoms of parathion blood ChE activities. Several other workers for overexposure and those apparently symptom-free. whom no preexposure ChE activities had been ob­ However, the plasma ChE activity was 20% lower tained appear to have exhibited significant depres­ in the group with symptoms of parathion sions in blood ChE activities. The results of this overexposure than in those not complaining of study indicate that continuous exposure to air­ symptoms. The sprayers were exposed for a few borne parathion in a concentration range of 0.1- days during each 10-day interval over a 2-month 0.8 mg/m3 may pose a hazard to the health of wor­ period. Airborne parathion concentrations col­ kers. However, the data do not provide firm lected in the operators’ breathing zone ranged evidence of what airborne concentration of from 2.0 to 15.0 mg/m3. Erythrocyte and plasma parathion, if any, in this range constitutes a safe ChE activities were determined both during and exposure. The results obtained by Brown and subsequent to spraying in order to establish normal Bush79 can be used only to indicate a suspected activity levels. These results of intermittent expo­ unsafe continuous exposure level to airborne sure demonstrate the hazard involved in a continu­ parathion, namely, the average value obtained for ous exposure to airborne concentrations of the 8 sampling sites, or approximately 0.25 mg/m3. parathion in the range of 2.0 to 15.0 mg/m3. Con­ In the absence of additional published data comitant dermal exposure, which is significant in similar to that of Brown and Bush79 upon which an the application of parathion,46 compounds the environmental standard for parathion can be hazard. directly based, an indirect estimate based on ex­ The only reported study of parathion exposure trapolation from a demonstrated safe daily oral dose in humans must be made. and plasma ChE activities were measured at vari­ Rider et al14 administered parathion to human ous times. Daily ingestion of 0.6, 1.2, 2.4, and 4.8 volunteers at dosages of 3.0, 4.5, 6.0, and 7.5 mg parathion by human volunteers resulted in no mg/day. Each phase of the study was conducted significant effects on whole blood ChE activity. on groups of 7 subjects, 5 of whom served as test However, in 4 women receiving 7.2 mg parathion subjects and 2 as controls. The study was divided daily, 5 days/week, whole blood ChE activity into three periods: ( 1 ) a pretest period of approxi­ declined to 67% of control activity after 6 weeks. mately 30 days during which normal plasma and At this time, RBC and plasma ChE activities were RBC ChE activities were determined; (2) an ap­ 84% and 63% of control levels, respectively. proximately 30-day test period during which Within 28 days of withdrawal of parathion, whole parathion was taken orally by the subjects; and (3) blood ChE was restored to approximately 87% of a post-test period. Plasma and RBC ChE activities control activity. Thus, the daily oral intake of 4.8 were measured twice each week throughout each mg of parathion was shown to be safe for humans phase. None of the subjects receiving the two based on response of the blood ChE activity. The lowest daily dosages, 3.0 and 4.5 mg, exhibited sig­ maximum daily no-effect level was estimated by nificant depressions in either plasma or RBC ChE the authors to be 0.05 mg/kg. activities. The investigators reported a slight but Rider et al! plasma ChE’s occurred as the result of inhalation primarily from skin contact and absorption, it is exposure of male rats to 0.74 mg parathion/m3 of recommended that appropriate work practices and air breathed. protective measures be required regardless of the In adult male dogs exposed to parathion aerosol airborne concentration of parathion. For this 7-hours/day, 5-days/week, for 6 weeks, the follow­ reason, “occupational exposure to parathion” has ing results were obtained: a concentration of 0.001 been defined as employment in any area in which mg/m3 produced no significant inhibition of either parathion or materials containing parathion, alone RBC or plasma ChE’s; one of 0.01 mg/m3 also or in combination with other substances, is produced no significant inhibition of RBC ChE produced, packaged, processed, mixed, blended, during the 6-week exposure period; but the plasma handled, stored in large quantities, or applied. VI. WORK PRACTICES

Work practices are important for the control of trations of parathion were found to range from exposures to parathion. This is particularly true 0.25 to 0.4 mg/nr* in the breathing zone of wor­ because parathion is absorbed through the intact kers filling 50-lb cartons with parathion dust in the skin, mucous membranes, and eyes, as discussed in study by Brown and Bush.79 Airborne parathion Chapter III. Therefore, every effort must be made concentrations measured during mixing and load­ to avoid contamination of the skin via direct spills, ing of water-wettable powder were reported to splashes, or spray/dust, and indirectly via con­ average 2.15 mg/m:i in a mixing plant surveyed by taminated clothing or other materials. Should such Batchelor and Walker.1(Mi Air monitoring was con­ contamination occur, it is essential that the worker ducted by Kay et al5H while workers added 15% involved be taken immediately to an uncon­ parathion wettable powder to spray tanks. A mean taminated area and the contaminated clothing or airborne parathion concentration of 21 mg/m3 was equipment removed from the body, the skin and found. Such exposures are normally of short dura­ hair thoroughly and quickly washed with water tion; however, the level of exposure may be high (and preferably soap) or with other suitable enough to constitute a significant hazard. Where decontaminating solution, a physician contacted, adequate vapor and dust exhaust systems are not and the exposed worker placed under observation feasible, such as in certain field situations, workers for at least 24 hours. Contaminated clothing and engaged in mixing or loading of parathion in liquid other articles should be appropriately labeled and or powder (dust) form must wear a suitable safely stored until they can be washed or respiratory protective device. destroyed. The provision for basic sanitary facili­ Direct contamination is also possible during ties and their use is essential in minimizing dermal spray operations. The results of studies conducted exposures to parathion as reflected in the recom­ by Batchelor and Walker,1“ Jegier,107 and Simpson mendations in Chapter I, Section 7. and Beck10B showed that respiratory exposures of To protect against contamination by direct spraymen ranged from 0.03-0.26 mg/m:i in air-blast spills, it is recommended that workers handling spraying of orchards and fields to greater than 0.1 parathion wear adequate protective clothing in­ mg/m3 during use of hand knapsack sprayers on cluding impervious gloves, coveralls (covering en­ tomatoes. Kay et al5H in their study of Quebec tire body) or rubber aprons, impervious footwear, apple orchards measured airborne parathion con­ and a protective head covering. It is important that centrations ranging from 2 to 15 mg/m3 during the personnel such as shippers and warehousemen use of either hand-type or mechanical-rocker type handling nonleaking sealed containers of sprayers. High-pressure hand sprayers have parathion, such as drums, wear full-body coveralls generated 0.09 mg/m3 levels of airborne para­ and impervious gloves. The routine maintenance thion. 10

57 VII. RESEARCH NEEDS

Despite its decreasing usage, relatively large the demonstrated conversion of parathion quantities of parathion are currently being manu­ deposited on surfaces to other toxic substances. factured, formulated, mixed, and applied to vari­ (6) An epidemiologic study of a worker ous crops in the United States. Accordingly, the population exposed to parathion for a long period following research is recommended in order to add of time. In the event that an adequate cohort of to our existing knowledge of parathion: workers exposed to parathion cannot be identified, (1) Animal experiments to determine a retrospective morbidity and mortality study of a whether or not permanent effects on the central worker population exposed to parathion and other nervous system occur as the result of chronic low- ChE-inhibiting organophosphorus pesticides would level exposure. Well-designed and controlled be of great use in determining the long-term ef­ behavioral studies should be undertaken as a fects, if any, of these compounds. major part of the attempt to better define the ef­ (7) A program to develop more effective fects of parathion on the central nervous system. and satisfactory protective clothing for employees (2) Animal experiments to determine the working with parathion as well as other pesticides mutagenic, teratogenic, and carcinogenic poten­ (eg, cool, lightweight, and impervious to tials of parathion in realistic doses. parathion). (3) Electromyographic testing of human (8) Studies to develop an accurate and subjects exposed to parathion to determine par­ precise solid sampling system for airborne ticularly whether low concentrations of the insecti­ parathion. In addition, the recommended impinger cide produce adverse effects on the neurologic device should be thoroughly evaluated in order to system. determine its sampling efficiency and the overall (4) Studies to determine whether parathion precision of the recommended sampling and exerts any toxicity by a mechanism, or analytical method. mechanisms, other than inhibition of tissue ChE. (9) A research effort to develop an im­ (5) Additional studies to more clearly proved biologic test method to supersede blood define the environmental factors responsible for ChE determinations.

59 VIII. REFERENCES

1. Koelle OB. Drugs acting at synaptic and neuroeffector I 9 4. Safety Guide for Warehousing Parathions Washington. 21. Kalow W, Gunn DR: Some statistical data on atypical DC'. National Agricultural Chemicals Association. 1968, cholincsterase of human serum. Ann Hum Genet 23:239- 19 pp 50, 1959 5. Gaines TB: Acute toxicity of pesticides. Toxicol Appl 22. Diggle WM, Gage JC: Cholinesterase inhibition in vitro Pharmacol 14:515-34, 1969 by 0,0-diethvl O-p nitrophenyl thiophosphate (parathion, 6. Occupational Disease in California Attributed to Pesti E605 ). Biochem J 49:49 1-94, 1951 cides and Other Agricultural Chemicals, 1970. Berkeley, 23. Myers DK, Mendel B, Gersmann HR, Ketelaar JAA: O x­ Cal, California Dept of Public Health. Bureau of Occupa­ idation of thiophosphate insecticides in the rat. Nature tional Health and Environmental Epidemiology, 1971, 30 170:805-07, 1952 PP 24. Kubistova J: Parathion metabolism in female rat. Arch Int 7. Occupational Disease in California. 1970. Berkeley. Cal. Pharmacodyn 118:308-16, 1959 California Dept of Public Health. Bureau of Occupational 25. Murphy SD, Lauwerys RR, Cheever KL: Co nparative an­ Health and Environmental Epidemiology, 1971 ticholinesterase action of organophosphorus insecticides 8. Hatcher RE. Wiseman JS: Epidemiology of pesticide in vertebrates Toxicol Appl Pharmacol 12:22-35, 1968 poisoning in the Lower Rio Grande Valley in 1968 Tex 26. Berends F, Posthumus CH, Sluys IVD, Deierkauf FA: The Med 65:40 3, 1969 chemical basis of the “ageing process” of DEP-inhibited 9. Tabershaw 1R. Cooper WC: Sequel.ae of acute organic pseudocholinesterase Biochim Biophys Acta 34:576-78. phosphate poisoning. J Occup Med 8:5-20, 1966 1959 10. Occupational Disease in California Attributed to Pesti­ 27. Hobbiger F: Reactivation of phosphorylated cides and Other Agricultural Chemicals, 1963. Berkeley, acetylcholinesterase, in Eichler O. Earah A (eds): Hand­ Cal, California Dept of Public Health, Bureau of Occupa­ buch der Experimentellen Pharmakologie. Berlin, tional Health and Environmental Epidemiology. 1965, p 8 Springer-Verlag, 1963, vol 15, pp 92 1-88 11. Milby TH, Ottoboni F, Mitchell HW: Parathion residue 28. Wilson IB: Acetylcholinesterase—XL Reversibility of poisoning among orchard workers. JAMA 189:351-56, inhibition. J Biol Chem 190:1 1 I- 1964 ,17. 1951

12. Occupational Disease in California Attributed to Pesti­ 29. Childs AF, Davies DR, Green AL. Rutland JP: The re a c­ cides and Other Agricultural Chemicals, 1969. Berkeley, tivation by oximes and hydroxamic acids of Cholinesterase Cal, California Dept of Public Health, Bureau of Occupa­ inhibited by organo-phosphorus compounds. Brit J Phar­ tional Health and Environmental Epidemiology, 1971, pp m acol 10:462-65, 1955 3-4 30 Wilson IB: Molecular complementarity and antidotes for 13. Ouinbv GE, Lemmon AB: Parathion residues as a cause alkylphosphate poisoning. Fed Proc 18:75 2-58, 1959 of poisoning in crop workers. JAMA 166:740-46, 1958 31. Wilson IB;, Ginsburg S: Reactivation of 14. Holmstedt B: Structure-activity relationships of the or- acetylcholinesterase inhibited by alkylphosphate^. Arch ganophosphorus anticholinesterase agents, in Eichler O, Biochem Biophys 54:569-70, 1955 Earah A (edsi. Handbuch der Experimentellen Phar­ 32. Wilson IB: Transactions of the Faraday Society Meeting makologie. Berlin, Springer-Verlag, 1963, vol 15, pp 428- on the Physical Chemistry of Enzymes, 1955 85 33. Wilson IB, Ginsburg S: A powerful reactivator of al- 15. Metcalf RL, March RB: Studies of the mode of action of kylphosphate-inhibited acetylcholinesterase. Biochem parathion and its derivatives and their toxicity to insects. Biophys Acta 18:168-70, 1955 J Econ Entomol 42 721-28, 1949 34. Rider JA, Moeller HC, Puletti EJ, Swader Jl: Toxicity of 16. Hamblin DO, Golz HH: Parathion poisoning—A brief parathion, Systox, octamethyl pyrophosphoramide, and review. Ind Med Surg 24:65-72, 1955 methyl parathion in man. Toxicol Appl Pharmacol 17. Grob D, Garlick WL. Merrill GG, Freimuth HC: Death 14:603-1 1 , 1969 due to parathion, an anticholinesterase insecticide. Ann Intern Med 31:899-904, 1949 61 35. Edson EF: Summaries of toxicological data—No-effect 53. Kazen C. Bloomer A, Welch R, Oudbier A, Price H: Per­ levels of three organophosphutes in the rat. pig and man. sistence of pesticides on the hands of some occupationally Food Cosmet Toxicol 2:31 1-16, 1964 exposed people. Arch Environ Health 29:315-18, 1974 36 Rider JA, Moeller HC Suader J, Weilerstem RW: The ef­ 54. Williams EF: Properties of O.O-diethyl O p-nitrophen\ I fect of parathion on human red blood cell and plasma thiophosphate and O.O-diethyl O-p-nitropheny i cholinesterase, Section II. Arch Ind Flealth 18:442-45, phosphate Ind Eng Chem 43:950 54, 195! 1958 55. Parathion {0,0-dielhyi O-nitrophenyi phosphoiothioatc ). 37 Hartwell WV, Hayes GR Jr. Funckcs AJ: Respiratory ex­ revised 1969, Hygienic Guide Series Am Ind Hyg Assoc posure of volunteers to parathion. Arch Environ Health 30:308-12, 1969 8:820-25, 1964 56. The Condensed Chemical Dictionary, ed 8. Now York. 38. Hartwell WV. Hayes (iR Jr. Respiratory exposure to or­ Van Nostrand Reinhold Company, 1971, pp 658 59 ganic phosphorus insecticides. Arch Environ Health 57. Grob D: Anticholinesterase intoxication m man and its 1 i 564-68. 1^65 treatment, in Fichier O, Farah A *eds). Handbuch der 39. Hayes OR Jr. hunckes AJ, Hartwell WV: Dermal expo­ Experimentellen Pharmakologie. Bei lin. Springer - Verlag. sure of human volunteers to paiathion Arch Environ 1963. vol ¡5, pp 984 1027 Health fc:X2

66 APPENDICES

67 IX. APPENDIX I SAMPLING AND CALIBRATION PROCEDURES

The sampling method recommended is based on (3) Air pump: Any air mover capable of those described by Miles et al,UK and the NIOSH drawing the desired flowrate through the impinger Manual of Analytical Methods.197 As stated previ­ may be used, so long as the flowrate does not vary ously in Chapter IV, the sampling efficiency and more than ±5% during the sampling period. The the overall precision of the recommended sam­ sampling pump must be capable of operating at a pling and analytical method are unknown. In addi­ pressure drop of 1 inch of mercury while providing tion, the Environmental Protection Agency has the designated flow rate of 1-2 liters/min. The withdrawn the impinger (with ethylene glycol) flowrate of the pump must be calibrated and this sampling method from its pesticide manual. (RH calibration checked periodically to ensure that it Hill, Jr, written communication, March 1976) has not changed. However, the recommended method remains the (4) An integrating volume meter such as a best one presently available for collecting and dry-test or wet-test meter. determining the concentration of parathion in air. (5) Thermometer (6) Manometer Atmospheric Sampling (7) Stopwatch When sampling is performed for determination (8 I Filter cassette with glass-fiber filter, 8/u., of compliance with the recommended workplace 37 mm. air standard, the sample shall be taken within the (b) Calibration breathing zone of the exposed employee to ascer­ Since the accuracy of an analysis can be no tain the employee’s actual exposure to airborne greater than the accuracy of the air volume mea­ parathion. A description of sampling location and surement, the accurate calibration of a sampling conditions, equipment used, time and rate of sam­ pump is essential. How often the calibration must pling, and any other pertinent information shall be be performed is dependent on the use, care, and recorded at the time of the sample collection. handling of the pump. Pumps should also be re­ (a) Equipment calibrated if they have been misused or if they The sampling train consists of a midget impinger have just been repaired or received from a manu­ filled with 15 ml of ethylene glycol, an absorption facturer. If the pump receives hard usage, more tube, and an air pump. A prefilter unit consisting frequent calibration may be necessary. Regardless of the filter media and cassette filter holder can be of use, maintenance and calibration should be per­ used if needed. formed on a regular schedule and records of these (1) Midget impinger: All portions of the kept. impinger which may contact the collection medi­ Ordinarily, pumps should be calibrated in the um or the air stream before collection is effected laboratory both before they are used in the field must be made of glass. The collection medium is and after they have been used to collect a larpe ethylene glycol. The ethylene glycol used must be number of field samples. The accuracy of t'Lslih- free of substances that will produce interfering tion is dependent upon the type of instrument used peaks upon hexane extraction and subsequent gas as a reference. The choice of calibration instru­ liquid chromatographic analysis. Consequently, the ment will depend largely upon where the calibra­ only ethylene glycol suitable is that which has tion is to be performed. For laboratory testing, pri­ been preextracted and found to be free of interfer­ mary standards such as a spirometer or soapbubble ing substances by gas-liquid chromatography using meter are recommended, although other standard a flame photometric detector. calibration instruments (such as a wet-test meter (2) Absorption tube: An absorption tube or dry-gas meter) can be used. The actual setups loosely packed with a plug of glass wool is inserted will be similar for all instruments. between the exit arm of the impinger and the air Instructions for calibration with the soapbubble pump to protect against splash-over or water con­ meter appear below. If another calibration device densation. is selected, equivalent procedures should be used. 69 Since the flowrate given by a pump is dependent dividual employee's respiratory exposure are col­ on the pressure drop of the sampling device, in lected with the midget impinger by fastening the this case a midget impinger, the pump must be impinger to a coat lapel or shirt collar, or by hold­ calibrated while operating with a representative ing the impinger near the face of the employee midget impinger in line. The calibration train thus during the sampling period. The duration of sam­ consists of a soapbubbie meter, a midget impinger, pling shall be such that a concentration of 10^ of an absorption tube, a pressure gauge capable of the recommended environmental standard, as measuring 20 inches of water, and an air pump. specified in Chapter I, Section 1(a), may be de­ (1) The voltage of the pump battery is tected accurately by the recommended analytical checked with a voltmeter to ensure adequate volt­ method. An air sample of 25-50 liters should be age for calibration. The battery is charged if collected. The temperature and pressure of the at­ necessary. mosphere being sampled are measured and (2) The pump is turned on. The inside of recorded. the soapbubbie meter is then moistened by im­ After a sample is taken, the impinger stem is mersing the buret into the soap solution and draw­ removed and washed with 2-5 ml of ethylene ing bubbles up the inside until they are able to glycol. This wash solution is included in the imp­ travel the entire buret length without bursting. inger, and the amount of washing solution (3) The pump rotameter is adjusted to pro­ recorded. The top of the impinger is sealed tightly vide the desired flowrate. with a hard, nonreactive stopper (preferably (4) A water manometer is checked to en­ Tefloh). Do not seal with rubber. The impinger is sure that the pressure drop across the sampling placed upright in a carrying case, with care taken train is maintained at approximately 12 inches of to prevent losses due to spillage or evaporation. water at 2 liters/min. The trapped parathion is extracted into hexane (5) A soapbubbie is started up the buret, and analyzed as described in Appendix II. Other and the time required for the bubble to move from collection methods shown to be equivalent or su­ one calibration mark to another is measured with perior may be used. If shipment of the impingers a stopwatch. with the stems is preferred, the outlets of the (6) The procedure in (5) is repeated at stems should be sealed with paraffin sheet or other least twice, the results averaged, and the flowrate nonrubber covers, and the ground glass joints calculated by dividing the volume between the should be sealed (ie, taped) to secure the tops preselected marks by the time required for the tightly. A “ blank” impinger should be handled as soapbubbie to traverse the distance. the other samples (fill, seal, and transport) except (7) Calibration data which are to be that no air is sampled through this impinger. recorded include the volume measured, elapsed Where a prefilter has been used, the filter cas­ time or number of strokes, pressure drop, air tem­ settes are capped and placed in an appropriate perature, atmospheric pressure, serial number of cassette shipping container. One filter disc should the pump, date, and name of the person perform­ be handled like the other samples (seal and trans­ ing the calibration. port) except that no air is drawn through it. This is (c) Sampling Procedure labeled as a blank. Breathing zone samples representative of the in­

70 X. APPENDIX II ANALYTICAL METHOD FOR PARATHION

The gas-liquid chromatographic method (b) The cost of the equipment and supplies presented in the NIOSH Manual of Analytical may be somewhat expensive for some laboratories. Methods'1,7 is recommended for analysis of The sensitivity of the equipment depends on care­ parathion in air. NIOSH classifies the method as ful adjustment of the operating parameters. Con­ Class C (tentative), which is described as a tamination can occur easily through equipment method in wide use and which has been adopted and reagents. If interfering compounds are an­ as a standard method or recommended by another ticipated, a lengthy cleanup procedure is required. government agency or one of several professional agencies. Apparatus (a) Forceps. Principle of Method (b) Glass stirring rods. Parathion in workplace air is trapped in ethylene (c) Separatory funnels, 60-ml and 125-ml glycol contained in a midget impinger. The with Teflon stopcock. ethylene glycol solution is diluted with water and (d) Beakers, l()0-ml. extracted with hexane. The resulting solution of (e) Funnels, 65- or 75-mm (diameter at top). parathion in hexane is concentrated and subjected (f) Glass wool (preextracted with hexane). to gas-liquid chromatographic analysis using a (g) Hot water bath. phosphorus-specific flame photometric detector. (h) Kuderna-Danish evaporator-concentrator, consisting of a 125-ml Erlenmeyer-type flask, 3- Range and Sensitivity ball Snyder column, and 10-ml receiver graduated The linear range of the flame photometric de­ in milliliters. tector is 0.5-25 ng for parathion. For a 50-liter air (i) Glass beads, 3-mm. sample carried through the following procedure to (j) Volumetric flasks for standards. solution in I ml of hexane, 2 fx\ of which is in­ (k) Graduated cylinders, 25- or 50-ml. jected into the gas chromatograph, the range of (1) Syringes, 5- or 10-//.1 and 100-/U.1. workplace air concentrations over which analysis (m) Transfer pipets, volumetric. is linear is 5-250 /txg/m:i. These limits can be (n) Gas chromatograph, with attendant lowered or raised by changing (1) the volume of equipment, including a phosphorus flame air sampled, (2) the volume of the final hexane photometric detector. The following modification solution, or (3) the size of the aliquot injected into is suggested for operation of the GC with flame the gas chromatograph. photometric detection and is generally applicable to any GC. A switching valve should be interfaced Interferences between the gas chromatographic column and the detector. The valve, which is heated with a 432- Phosphorus compounds having retention times watt 2 V2 ” x 24” insulated heating tape, permits in­ close to that of parathion will interfere with the terchange of column effluent and nitrogen purge. analysis. The equipment used must be scrupulously The nitrogen purge flow rate is adjusted to equal cleaned to remove any traces of phosphate deter­ the flow from the gas chromatographic column so gents. Glassware should, in addition, be rinsed that when an interchange of flows is made for the with hexane immediately prior to use. purpose of venting solvent, no change is observed in the recorder baseline. This arrangement avoids Advantages and Disadvantages extinguishing the flame when sample injections are (a) The method is very sensitive and the de­ made. tector exhibits high specificity for phosphorus (o) Gas chromatography column constructed compounds. The analysis is performed directly on from 6 ft x 4 mm inside diameter borosilicate glass the compound of interest. Separation and quantifi­ (silanized) packed with one of the following: cation are accomplished in a reasonable amount of (1) 10% DC-200 (12,500 cst) on 80-100 time. mesh Gas Chrom Q. 71 (2) 15% OF-1 (10,000 cst)/ 10% DC-200 separatory funnel with 3 consecutive 2-ml portions ( 12,500 cst) on 80-100 mesh Gas Chrom Q. of hexane, washing down the walls of the funnel. (3) 2% diethylene glycol succinate (DECS) Allow each rinse to elute before adding the next. (C6 stabilized) on 80-100 mesh Gas Chrom O Finally, rinse the funnel and the sodium sulfate (4) 40} SE-30/6% QV-210 on 80-100 mesh with 2 more 2-ml portions of hexane. Chromosorb W, HP. (e) Set the Kuderna-Danish assembly in a Columns 1 and 2 are conditioned by heating 2-4 boiling watei bath and concentrate the extract to days at 240-250°C under nitrogen flowing at 60 about 5 ml. Remove the assembly from the bath ml/min, then primed by repeated injections of and, after it is cool, disconnect the receiving tube standard parathion solution under the conditions from the flask, rinsing the joint with a little hex­ of analysis given below Column 3 is conditioned ane Place the tube under a nitrogen stream at by heating 12 hours at 225-230°C under nitrogen room temperature and further concentrate the ex­ flowing at 60 ml/min. Column 4 is conditioned for tract to about 0.5 ml. Rinse down the wall of the at least 3 days at 245°C under nitrogen flowing at tube with hexane, delivered from a 1 00 -/la1 syringe, 60 ml/min. A column of 10% Carbowax 20M on diluting the extract to exactly 1.0 ml, and stir. 80-100 mesh silani/ed support (2 in x 4 mm inside (f) Inject a2-/xl aliquot of the hexane solution diameter glass tubing) is then attached before into the gas chromatograph and obtain a chro­ column 4 and the assembly is heated at 230-235°C matogram. The chromatographic conditions are: for ¡7 hours under nitrogen flowing at 20 ml/min. The 10% Carbowax 20M column is subsequently removed. Column temperature 220 C for columns 1 and 2 Reagents 210 C for column 3 200 C for column 4 interference-free(a) Ethylene glycol, interference-free(a) Injection port 225 C (pesticide quality). temperature (b) Hexane, interference-free (pesticide quality). Detector temperature 200 C (c) Distilled water, interference-free. Transfer line 235 C (d) Saturated aqueous sodium chloride, inter­ temperature ference-free. Switching valve 235 C (e) Anhydrous sodium sulfate. temperature (f) Parathion of known purity. Carrier gas (nitrogen) 120 ml/min for columns 1 and 2; flow 60 ml/min for column 3; and Procedure 75 ml/min for column 4. (a) The sample in 17-20 ml of ethylene glycol is transferred to a 125-ml separatory funnel. (The reagent quantities and glassware sizes The retention times (relative to parathion) at specified below apply to a sample in 20 ml of these conditions for parathion, related analytes, ethylene glycol and must be scaled proportionately and some interfering organophosphorus pesticides for different volumes.) Wash the sample container are tabulated Table X -l. with a measured amount of water and add the The solvent-flush sample injection technique is washings to the separatory funnel. Dilute the recommended. Duplicate injections should be ethylene glycol with a total of 70 ml of water. made. The hexane, which precedes the parathion (b) Extract the aqueous solution 3 times with should be vented according to (n) under Ap­ 1 2-ml portions of hexane (total of 36 ml). paratus so that the detector flame is not extin- (c) Extract the combined hexane extracts 2 guished. The conditions of the run should be such times with 10-ml portions of distilled water. that no parathion is lost during the venting (d) Dry the hexane solution by passing it process. through 2.6 g of anhydrous sodium sulfate con­ (g) By comparison to standard curves for tained in a funnel with a glass wool retaining plug parathion, average of the area under the parathion at the top of the stem. Collect the eluate in a 125- peak is converted to the amount in ng of parathion ml Kuderna-Danish flask which has been fitted seen by the detector. Paraoxon, if present in the with a 10-ml receiving tube containing one 3-mm sample, can be quantitated by comparison of its glass bead. W'hen the extract has eluted, rinse the peak area with a standard curve for paraoxon. 72 TABLE X -l RETENTION TIMES — PARATHION AND OTHER COMPOUNDS OF INTEREST OP Compound Column 1 Column 2 Column 3 Column 4 Parathion 1.00 1.00 1.00 1.00 (4.4 min) (8 min) (3 4 min) Paraoxon 0.77 1.13 1.23 1.17 Methyl parathion 0.73 0.78 1.18 0.76 Methyl paraoxon 0.56 0.88 1.41 0.90 Amino parathion 1.04 0.78 Dursban 1.00 0.97 Ruelene 1.01 1.12 Adapted from NIOSH Manual of Analytical Methods [197].

Calibration and Standards (a) Prepare at least 3 standard solutions in from calibration curve based on peak area the concentration range 100-10,000 ng/ml from a responses stock solution of parathion in hexane. Solution = volume in ¿¿1 of the final hexane (b) Make duplicate injections of aliquots of volume solution (usually 1 ml) each parathion standard solution onto the chro­ Injection = volume in ¿¿I of the aliquot of the matographic column and determine the peak volume final hexane solution injected into areas. the gas chromatograph (c) Plot the amount in ng of parathion seen by the detector vs the peak area. A straight line passing through the origin should result. If these (b) Convert the volume of air sampled to conditions are not observed, either the linear standard conditions (25°C, 760 mmHg): range of the detector has been exceeded or a system malfunction has occurred. (d) Injections of standards should be inter­ spersed among sample injections in order to moni­ where: V(s) = volume of air in liters at 25°C and 760 tor detector sensitivity. mmHg Calculations V = volume of air in liters as measured P = barometric pressure in mmHg (a) Determine the total amount in ng of T = temperature of air in degrees Celsius parathion present in the sample: (c) The concentration of parathion can be expressed in ng/liter or £ig/m:i: Sample weight _ ^ Solution volume of parathion (ng) = ng(0) X-——------; ------(u) g/cu m = ng/liter Injection volume or where: (u) g/cu m = total ng ng(0) = nanograms of parathion determined V (s)

73 XI. APPENDIX III METHOD FOR BIOCHEMICAL DETERMINATION OF BLOOD CHOLINESTERASES Apparatus The method of Wolfsie and Winter,147 a micromodification of the Michel method,133 is (a) Centrifuge capable of 3,500 rpm and recommended for the measurement of holding capillary sample tubes. cholinesterase activity. (b) A pH meter, calibrated to 0.01 pH units. (c) 0.02 ml Sahli-type hemoglobin pipet. Reagents (d) Constant-temperature bath, 25°C. All reagents should be at least ACS reagent (e) 100-and 1,000-ml volumetric flasks. grade. (f) Heparinized capillary tubes. (a) Buffer Solution I (for erythrocytes) (g) A Bunsen burner. For 1 liter of buffer, dissolve 4.1236 g sodium Sampling, Handling, and Preparation barbital (0.02 M), 0.5446 g potassium orthophosphate, di-H (0.004 M), and 44.730 g Blood is collected from a clean, dry fingertip in potassium chloride (0.60 M) in 900 ml of distilled a heparinized glass capillary tube. The blood is al­ water; 28.0 ml of 0.1 N hydrochloric acid is added lowed to flow into the capillary tube until the tube while shaking the solution, and the flask is brought is approximately % full, leaving one end free by 1- to volume with distilled water. The pH of Buffer I 1.25 inches, to permit flame-sealing of the tip of should be 8.10 at 25°C. the tube without overheating the blood sample. (b) Buffer Solution II (for plasma) The finger should be pricked deeply and care For 1 liter of buffer, dissolve 1.2371 g sodium should be taken to collect only free-flowing drops barbital (0.006 M), 0.1361 g potassium of blood in order to guard against the initiation of orthophosphate, di-H (0.001 M), and 17.535 g the clotting process before the blood contacts the sodium chloride (0.30 M) in 900 ml of distilled heparin lining in the wall of the capillary. water and add 1 1.6 ml of 0.1 N hydrochloric acid One end of the capillary is plugged with solid before bringing to volume. The pH of Buffer II (room temperature) paraffin and the other (free) should be 8.00 at 25°C. end is sealed in the flame of a Bunsen burner. The The pH of the buffer solutions will decrease capillary may now be labeled with an adhesive over a period of several weeks. The pH should be tape tag bearing a serial number or name and checked before using and, if it has dropped more date. The sample should then be centrifuged at than 0.03 pH units, it should be discarded and a 3,000-3,500 rpm for 50-60 minutes. When the fresh solution made. sample has been so treated, it may be shipped to a (c) Acetylcholine Substrate (for erythro­ laboratory, if necessary, or stored for several days cytes) (preferably in a refrigerator) without appreciable This is 0.1 1 M acetycholine chloride (2.000 g in change. 100 ml of distilled water). (d) Acetylcholine Substrate (for plasma) Analysis This is 0.165 M acetycholine chloride (3.000 g For analysis, the capillary is cut cleanly with a in 100 ml of distilled water). sharp ampul file. From the packed-cells section of A few drops of toluene are added to each the capillary, draw 0.02 ml directly into a Sahli- acetylcholine substrate solution as a preservative, type hemoglobin pipet. The ends of the capillary and the solutions are refrigerated when not in use. must be cut evenly to provide satisfactory jux­ The acetylcholine solutions should not be retained taposition with the tip of the pipet. Discharge the for more than 1 week. contents of the pipet directly into 1.0 ml of 0.01% (e) Saponin Solution saponin solution in a microbeaker, and rinse the This is 0.010% saponin (100 mg in 1,000 ml of pipet well (3 times) into the solution. Glass vials, I distilled water). This solution should be made inch (2.5 cm) deep by % inch (19 mm) in diame­ fresh as needed. ter, are convenient for electrometric testing. They 75 will fit in the carrier of a standard pH meter, and, Calculations when used with a clean rubber stopper, will The final units derived from this assay are eliminate transfer of the sample from a test tube ApH/hour: for each pH measurement. Plasma is taken from the appropriate section of the capillary in the same manner as the packed erythrocytes and discharged Delta pH/hour = pH (i) - pH (f) - be into 1.0 ml of distilled water, the Sahli pipet being t(f) -t(i) rinsed into the solution (3 times) as with the erythrocytes. where: Erythrocyte Cholinesterase Assay pH (i) = initial pH pH (f) = final pH (a) One milliliter of hemolyzed erythrocytet (f) — t (i) = time elapsed inhours between reading solution is added to 1 ml of buffer solution I and pH (i) and reading pH (f) placed in a 25°C water bath. (b) After a 10-minute equilibrium period, the b = nonenzymatic hydrolysis corresponding initial pHi is determined to the nearest 0.01 pH to pH (f) unit with the pH meter. c = correction forvariations in delta (c) Two-tenths miliiliter of 0.11 M pH/hour with pH, corresponding acetylcholine chloride solution is added with rapid to pH (f) mixing and the time is recorded. (d) The reaction proceeds for 1-1.5 hours be­ fore the final pHf is noted. The b and c correction factors are given in The beaker containing the solution should be Table XI-1.,M Average baseline values of erythro­ shaken when the glass electrode is introduced to cyte and plasma cholinesterase activity determined speed the establishment of equilibrium. by this method for healthy nonexposed men and Note: The buffer solution I is designed to yield a women are given in Table XI-2.145 147 The value for pH of 8.00 after the addition of hemolyzed human average RBC ChE activity for men is drawn from erythrocytes. Wolfsie and Winter.14, The value for women is ob­ tained by multiplying the average RBC ChE activi­ Plasma Cholinesterase Assay ty figure for men147 by the ratio of mean ApH/hr (a) One milliliter of diluted plasma is mixed for women to mean ApH/hr for men derived from with 1 milliliter of buffer solution II. the data of Rider et al.145 The use of the data of (b) The solution is allowed to equilibrate in a Wolfsie and Winter147 allows for the increased 25°C water bath for 10 minutes. packing and possible contamination of RBC’s by (c) At the end of 10 minutes, the initial pHj plasma ChE. Plasma ChE values were selected is noted to the nearest 0.01 pH unit. from Rider et al,145 since their larger data base (d) Two-tenths milliliter of 0.165 M probably provides a closer approximation of the acetylcholine chloride solution is added with rapid true population mean of normal values tor plasma mixing. ChE activity. For the same reason, their data pro­ (e) The reaction mixture is incubated for 1- vide the most reliable women/men ratio for 1.5 hours before the final pHf is noted. RBC ChE activities.

76 TABLE XI-1 TABLE XI-2 CORRECTION FACTORS FOR USE IN EQUATION FOR ApH/HR MEAN BASELINE VALUES Erythrocyte/ Plasma/ OF ERYTHROCYTE AND Cholinesterase Cholinesterase PLASMA CHOLINESTERASE IN MEN Corrections Corrections AND WOMEN [a pH /H R ] pH (f) b c b c Erythrocyte Cholinesterase 7.9 0.03 0.94 0.09 0.98 Men Women 7.8 0.02 0.95 0.07 1.00 Mean 0.861 0.843 7.7 0.01 0.96 0.06 1.01 7.6 0.00 0.97 0.05 1.02 Plasma Cholinesterase 7.5 0.00 0.98 0.04 1.02 ______M ean______0.953______0.817______7.4 0.00 0.99 0.03 1.01 Adapted from Rider et al [145] and Wolfsie and Winter [147]. 7.3 0.00 1.00 0.02 1.01 7.2 0.00 1.00 0.02 1.00 7.1 0.00 1.00 0.02 1.00 7.0 0.00 1.00 0.01 1.00 6.8 0.00 0.99 0.01 1.00 6.6 0.00 0.97 0.01 1.01 6.4 0.00 0.97 0.01 1.02 6.2 0.00 0.97 0.01 1.04 6.0 0.00 0.99 0.01 1.09 Adapted from Michel [133]. TABLE XI-3

NORMAL VALUES FOR CIRCULATING CHOLINESTERASES IN HEALTHY NONEXPOSED PERSONS* Subjects Erythrocyte Cholinesterase Plasma Cholinesterase Reference Activity (A pH/hr) Activity (A pH/hr) Range Mean SD Range Mean SD 400 men 0.58- 0.52- Rider et al** 0.95 0.766 0.081 1.39 0.953 0.187 [145] 400 women 0.56- 0.38- 0.94 0.750 0.082 1.25 0.817 0.187 255 men 0.554- 0.408- Wolfsie & Winter*** 1.252 0.861 0.091 1.652 0.912 0.112 [147] 120 men & 0.58- Vorhaus and Kark women —— — 1.37 0.94 0.16 [146] 20 men ——— — 0.95 0.24 Fremont-Smith et al [200] 20 women —— — ■—■ 0.78 0.12 * All analyses performed by method of Michel. [133] ** Ranges, means, and standard deviations in this study are estimates based on data extrapolated to age 40; ranges reflect elimination of highest 1% and lowest 1% of values. *** Analytic method modified for smaller blood sample.

77 XII. APPENDIX IV DIAGNOSIS AND MEDICAL MANAGEMENT OF PARATHION POISONING

The text appearing immediately below is to the provision of very rigorous supportive and adapted in large part from a publication entitled antidotal measures in severe cases. In the Prevention and Management of Organophosphate moderate to severe cases, weakness of the muscles Poisoning. This material, approved in 1970 by the of respiration may necessitate the use of positive AMA Committee on Occupational Toxicology ofpressure artificial respiration. Careful attention the Council on Occupational Health, originally ap­ must be paid to removal of secretions and to main­ peared in the Journal of the American Medical tenance of a patent airway. Anticonvulsants, such Association in 1971.201 as trimethadione and sodium thiopental, may be (a) Diagnosis necessary. The critical point is that respiration A diagnosis of parathion intoxication is based must be maintained since death usually results primarily on a definite history of exposure to the from respiratory failure (usually accompanied by a material usually 6 hours or less before onset of ill­ secondary cardiovascular component) due to ness plus clinical evidence of diffuse parasym­ weakness of the muscles of respiration and to ac­ pathetic stimulation. Laboratory verification is cumulation of excessive secretions in the upper based on depression of plasma and RBC ChE to a respiratory tract. If therapy is to be effective, it level substantially (509Î or more) below preexpo­ must be instituted with the least possible delay. To sure values determined according to the recom­ relieve the symptoms of excess parasympathetic mended standard. Monitoring of RBC ChE activity stimulation, large (heroic) doses of atropine are levels, as specified in the recommended standard, usually required. is intended to prevent the development of poison­ For adults, as much as 2-4 mg (1/30 g to 1/15 ing by removing the exposed worker from the g) should be administered by intravenous or in­ toxic environment at a point prior to the develop­ tramuscular injection every 5-10 minutes until ment of signs and symptoms. In actual practice, signs of atropinization appear: dry, flushed skin; the ChE test is often of value as a confirmatory, tachycardia as high as 140 beats/minute; dilation rather than a diagnostic, procedure. In treating pa­ of the pupils. Obviously, caution must be exercised tients with moderate to severe parathion poison­ in administering these amounts of atropine. No ing, the clinician should act on his clinical impres­ generalization of the amount necessary is possible; sion and on the history of exposure rather than the dose is administered according to the patient’s wait for laboratory confirmation of ChE activitycondition. As much as 50 mg may be required the depression. first day. A mild degree of atropinization should Initial signs and symptoms of parathion intoxica­ be maintained as long as symptoms are in tion are usually giddiness, sometimes accompanied evidence. by headache, constriction of the pupils (miosis), Although atropine remains the drug of choice, and tightness in the chest. Nausea, vomiting, particularly if the treatment must be continued for sweating, blurred vision, weakness, diarrhea, ab­ more than a day or two, pralidoxime (Protopam; dominal cramps, and pallor may follow. In 2-PAM) chloride is a commercially available an­ moderate to severe cases of intoxication, signs and tidote which complements atropine and hastens symptoms may also include dyspnea, salivation, the reactivation of parathion-inhibited ChE’s. For lacrimation, muscular twitchings, convulsions, adults moderately to severely poisoned by cyanosis, shock and cardiac arrhythmias, coma, parathion, pralidoxime chloride should be used and possibly death. Greatly increased salivary and along with atropine, injected intravenously as an bronchial secretions are common. In the case of initial dose of 1 g at a rate not in excess of 500 mild poisoning, where the differential diagnosis mg/minute. If weakness is not relieved or if it may be puzzling, the results of the cholinesterase recurs after 20 minutes, the dose may be repeated. test may be necessary to establish a definite diag­ After an overwhelming inhalation, skin exposure, nosis. or ingestion of parathion, the doses may be dou­ (b) Treatment bled. For children, the usual dose is 25-50 mg/kg Treatment of parathion poisoning ranges from of body weight. Treatment with pralidoxime simple removal from exposure in very mild cases chloride will be most effective if given within 24 79 hours after poisoning. (Its usefulness after 36-48 suspected, the following measures should be put hours is questionable.) Together, the 2 antidotes, into effect immediately: atropine and pralidoxime chloride, are more effec­ (1) If the patient is not breathing, start ar­ tive in treating parathion poisoning than is either tificial respiration. one alone. Morphine and other respiratory depres­ (2) In all cases of suspected parathion sant drugs, theophylline and aminophylline, are poisoning, call a physician at once. specifically contraindicated because they accentu­ (3) If parathion has been swallowed, in­ ate symptoms. duce vomiting by sticking a finger into the throat, It is of great importance to decontaminate the by giving warm salt water (one tablespoonful of patient. The stomach should be lavaged and a salt to a glass of water), or by giving soapy water. saline cathartic administered if parathion has been Repeat until vomit fluid is clear. Make the victim ingested. However, nothing should ever be given drink plenty of water or milk, if available; how­ by mouth to an unconscious person. Contaminated ever, NEVER GIVE ANYTHING BY MOUTH clothing should be removed at once and the skin TO AN UNCONSCIOUS PERSON. and hair should be washed with generous amounts (4) If the patient has been poisoned by of water (and preferably soap) or other suitable contact with the insecticide, move him away from decontaminating solution. Cleansing may be best the possibility of any further exposure. If parathion accomplished under a shower or by submersion in has been spilled or splashed onto the clothes or a pond or other body of water it the exposure oc­ skin, remove clothing immediately and wash the curred in the field. Careful attention should be skin thoroughly with water (and preferably soap) paid to cleansing of the hair. The patient should or other suitable decontaminating solution; use be attended and monitored continuously for a copious amounts of water/decontaminating solu­ minimum of 24 hours, since serious and sometimes tion in rinsing. If splashed into the eyes, wash con­ fatal relapses have occurred because of continuing tinuously with copious amounts of water for at absorption of the insecticide or dissipation of the least 15 minutes. Care should be taken to prevent effects of the antidote. contamination of the skin and clothing of those (c) First-Aid Measures providing first aid. Industrial handbooks discussing the use of vari­ (5) Keep the patient lying down, quiet, and ous OP compounds typically include a section on warm. Take him to the nearest source of medical first aid. care if not available at the scene of poisoning. General signs and symptoms of parathion (6) Try to find out the names of all pesti­ poisoning are headache, blurred vision, weakness, cides (including the names of their active in­ nausea and vomiting, cramps, looseness of the gredients) with which the patient has been work­ bowels and pain or tightness in the chest. Signs ing or with which he has been contaminated and and symptoms may also include sweating, pinpoint tell the physician. Take a label from the container pupils (even when in the shade), drooling, water­ (or a clean, labeled container) to the physician ing eyes, difficulty in breathing, and convulsions. along with any other available literature describing If the above warning signs and symptoms are the products involved. definitely observed and parathion poisoning is

80 XIII. APPENDIX V MATERIAL SAFETY DATA SHEET

The following items of information which are system of nomenclature. Where possible, avoid applicable to a specific product or material shall using common names and general class names, be provided in the appropriate block of the such as “aromatic ,” “safety solvent,” or Material Safety Data Sheet (MSDS). “aliphatic hydrocarbon,” when the specific name The product designation is inserted in the block is known. in the upper left corner of the first page to The “%” may be the approximate percentage by facilitate filing and retrieval. Print in upper case weight or volume (indicate basis) which each letters as large as possible. It should be printed to hazardous ingredient of the mixture bears to the read upright with the sheet turned sideways. The whole mixture. This may be indicated as a range product designation is that name or code designa­ or maximum amount, ie, “ 10-40% vol” or “ 10% tion which appears on the label, or by which the max wt” to avoid disclosure of trade secrets. product is sold or known by employees. The rela­ Toxic hazard data shall be stated in terms of tive numerical hazard ratings and key statements concentration, mode of exposure or test, and are those determined by the rules in Chapter V, animal used, eg, “ 100 ppm LC5()-inhalation-rat,” Part B, of the NIOSH publication, An Identification “25 mg/kg LD50-skin-rabbit,” “75 ppm L.C man,” System for Occupationally Hazardous Materials. or “permissible exposure from 29 CFR The company identification may be printed in the 1910.1000,” or, if not available, from other upper right corner if desired. sources of publications, such as the American (a) Section I. Product Identification Conference of Governmental Industrial Hygienists The manufacturer’s name, address, and regular or the American National Standards Institute Inc. and emergency telephone numbers (including area Flammable or reactive data could be flashpoint, code) are inserted in the appropriate blocks of shock sensitivity, or other brief data indicating na­ Section I. The company listed should be a source ture of the hazard. of detailed backup information on the hazards of (c) Section III. Physical Data the material(s) covered by the MSDS. The listing The data in Section III should be for the total of suppliers or wholesale distributors is mixture and should include the boiling point and discouraged. The trade name should be the melting point in degrees Fahrenheit (Celsius in product designation or common name associated parentheses); vapor pressure, in conventional mil­ with the material. The synonyms are those com­limeters of mercury (mmHg); vapor density of gas monly used for the product, especially formal or vapor relative to the density of air (air=l); chemical nomenclature. Every known chemical solubility in water, in parts/hundred parts of water designation or competitor’s trade name need not by weight; specific gravity (water=l); percent be listed. volatiles (indicated whether by weight or volume) (b) Section II. Hazardous Ingredients at 70 degrees Fahrenheit (21.1 degrees Celsius); The “materials” listed in Section II shall be evaporation rate for liquids or sublimable solids, those substances which are part of the hazardous relative to the evaporation rate of butyl acetate; product covered by the MSDS and individually and appearance and odor. These data are useful meet any of the criteria defining a hazardous for the control of toxic substances. Boiling point, material. Thus, one component of a multicom­ vapor density, percent volatiles, vapor pressure, ponent product might be listed because of its tox­ and evaporation rate are useful for designing icity, another component because of its flamma- proper ventilation equipment. This information is bility, while a third component could be included also useful for design and deployment of adequate both for its toxicity and its reactivity. Note that a fire and spill containment equipment. The ap­ MSDS for a single component product must have pearance and odor may facilitate identification of the name of the material repeated in this section substances stored in improperly marked con­ to avoid giving the impression that there are no tainers, or when spilled. hazardous ingredients. (d) Section IV. Fire and Explosion Data Chemical substances should be listed according Section IV should contain complete fire and ex­ to their complete name derived from a recognized plosion data for the product, including flashpoint and autoignition temperature in degrees clude those products released under fire condi­ Fahrenheit (Celsius in parentheses); flammable tions. It must also include dangerous products limits, in percent by volume in air; suitable extin­ produced by aging, such as peroxides in the case guishing media or materials; special firefighting of some ethers. Where applicable, shelf life should procedures; and unusual fire and explosion hazard also be indicated. information. If the product presents no fire hazard, (g) Section VII. Spill or Leak Procedures insert “NO FIRE HAZARD” on the line labeled Detailed procedures for cleanup and disposal “Extinguishing Media.” should be listed with emphasis on precautions to (e) Section V. Health Hazard Information be taken to protect workers assigned to cleanup The “Health Hazard Data” should be a com­ detail. Specific neutralizing chemicals or bined estimate of the hazard of the total product. procedures should be described in detail. Disposal This can be expressed as a TWA concentration, as methods should be explicit including proper label­ a permissible exposure, or by some other indica­ ing of containers holding residues and ultimate tion of an acceptable standard. Other data are ac­ disposal methods such as “sanitary landfill,” or ceptable, such as lowest LD50, if multiple com­ “incineration”. Warnings such as “comply with ponents are involved. local, state, and federal antipollution ordinances” Under “Routes of Exposure,” comments in each arc proper but not sufficient. Specific procedures category should reflect the potential hazard from shall be identified. absorption by the route in question. Comments (h) Section VIII. Special Protection Informa­ should indicate the severity of the effect and the tion basis for the statement, if possible. The basis might Section VIII requires specific information. State­ be animal studies, analogy with similar products, ments such as “Yes,” “No,” or “If necessary" are or human experiences. Comments such as “yes" or not informative. Ventilation requirements should “possible” are not helpful. Typical comments be specific as to type and preferred methods. might be: Respirators shall be specified as to type and NIOSH or US Bureau of Mines approval class, ie, Skin Contact—single short contact, no ad­ “Supplied air,” “Organic vapor canister,” verse effects likely; prolonged or repeated “Suitable for dusts not more toxic than lead,” etc. contact, local sweating and muscular fibril­ Protective equipment must be specified as to type lation. and materials of construction. (i) Section IX. Special Precautions Eye Contact—constriction of iris; poor vi­ “ Precautionary Statements” shall consist of the sion in dim light; scleral injection. label statements selected for use on the container or placard. Additional information on any aspect of safety or health not covered in other sections “Emergency and First Aid Procedures” should should be inserted in Section IX. The lower block be written in lay language and should primarily can contain references to published guides or in- represent first-aid treatment that could be pro­ house procedures for handling and storage. De­ vided by paramedical personnel or individuals partment of Transportation markings and classifi­ trained in first aid. cations and other freight, handling, or storage Information in the “Notes to Physician” section requirements and environmental controls can be should include any special medical information noted. which would be of assistance to an attending (j) Signature and Filing physician including required or recommended Finally, the name and address of the responsible preplacement and periodic medical examinations, person who completed the MSDS and the date of diagnostic procedures, and medical management completion are entered. This will facilitate cor­ of overexposed workers. rection of errors and identify a source of addi­ (f) Section VI. Reactivity Data tional information. The comments in Section VI relate to safe The MSDS shall be filed in a location readily ac­ storage and handling of hazardous, unstable sub­ cessible to workers potentially exposed to the stances. It is particularly important to highlight in­ hazardous material. The MSDS can be used as a stability or incompatibility to common substances training aid and basis for discussion during safety or circumstances such as water, direct sunlight, meetings and training of new employees. It should steel or copper piping, acids, alkalies, etc. assist management by directing attention to the “Hazardous Decomposition Products” shall in­ need for specific control engineering, work prac- 82 tices, and protective measures to ensure safe han­ dling and use of the material. It will aid the safety and health staff in planning a safe and healthful work environment and suggesting appropriate emergency procedures and sources of help in the event of harmful exposure of employees.

83 MATERIAL SAFETY DATA SHEET 1 PRODUCT IDENTIFICATION

REGULAR TELEPHONE NO. MANUFACTURER'S NAME EMERGENCY TELEPHONE NO

ADDRESS TRADE NAME SYNONYMS II HAZARDOUS INGREDIENTS

MATERIAL OR COMPONENT % HAZARD DATA

III PHYSICAL DATA

BOILING POINT 760 MM HG MELTING POINT

SPECIFIC GRAVITY tHjOM) VAPOR PRESSURE

VAPOR DENSITY IAlR- 1} SOLUBILITY IN H20. % BY WT

% VOLATILES BY VOL EVAPORATION RATE (BUTYL ACETATE U

APPEARANCE AND ODOR

84 IV FIRE AND EXPLOSION DATA

FLASH POINT AUTOIGNITION (TEST METHOD) TEMPÉRATURE

FLAMMABLE LIMITS IN AIR, % BY VOL. LOWER UPPER

EXTINGUISHING MEDIA

SPECIAL FIRE FIGHTING PROCEDURES

UNUSUAL FIRE ANO EXPLOSION HAZARD

V HEALTH HAZARD INFORMATION

HEALTH HAZARD DATA

ROUTES OF EXPOSURE

INHALATION

SKIN CONTACT

SKIN ABSORPTION

tYE CONTACT

INGESTION

EFFECTS OF OVEREXPOSURE ACUTE OVEREXPOSURE

CHRONIC OVEREXPOSURE

EMERGENCY AND FIRST AID PROCEDURES

EYES

SKIN

INHALATION

INGESTION

NOTES TO PHYSICIAN

85 VI REACTIVITY DATA

CONDITIONS CONTRIBUTING TO INSTABILITY

INCOMPAT iBILITY

HAZARDOUS DECOMPOSITION PRODUCTS

CONDITIONS CONTRIBUTING TO HAZARDOUS POLYMERIZATION

VII SPILL OR LEAK PROCEDURES

STEPS TO BE TAKEN IF MATERIAL IS RELEASED OR SPILLED

NEUTRALIZING CHEMICALS

WASTE DISPOSAL METHOD

VIII SPECIAL PROTECTION INFORMATION

VENTILATION REQUIREMENTS

SPECIFIC PERSONAL PROTECTIVE EQUIPMENT

HESPIRATORY (SPECIFY IN DETAIL)

EYE

GLOVES

OTHER CLOTHING AND EQUIPMENT

86 IX SPECIAL PRECAUTIONS

PRECAUTIONARY STATEMENTS

OTHER HANDLING AND STORAGE REQUIREMENTS

PREPARED BY

ADDRESS

DATE

87 XIV. APPENDIX VI SUMMARY OF PERTINENT CALIFORNIA STATE PESTICIDE REGULATIONS, 1974

Under the California regulations,202 employers occurred that might reasonably be expected to must arrange medical supervision for all workers lead to an illness.”202 To prevent the simple mask­ who mix, load, apply, or flag Category 1 (highlying of symptoms, atropine may not be taken by an toxic) pesticides for more than 30 hours in any 30- employee except under direction of a physician. day period. According to these regulations, Neither pilots of agricultural aircraft nor em­ parathion is considered a Category 1 pesticide. ployees under the age of 1 8202 are permitted to This supervision includes preexposure baseline mix or load pesticides in Category 1 or 2 unless ChE determinations and periodic biologic monitor­ closed mixing or loading systems are used. Persons ing of RBC and plasma ChE activities. It also in­ handling pesticides in Category 1 are not allowed cludes authority for the physician to instruct the to work alone. Radio, telephone, or personal con­ employer to remove an employee from all occupa­tact at least once every 2 hours during the day or tional exposure to and carba­ every hour at night may be substituted for the mates should monitoring reveal depression of presence of a second person. Operators of ground plasma ChE to 50% of the preexposure baseline or vehicles who are able to see each other’s applica­ RBC ChE to 40% of the preexposure baseline. tion vehicles or operating lights are not considered Both ChE activities must return to within 20% of to be working alone. Pilots and either mixer- the preexposure baseline before the employee can loaders or flaggers are not considered alone when resume exposure to organophosphates or carba­ working as a team. mates. Whenever a ChE test indicates a depression Changing areas equipped with towels, soap, and of 30% or more, a retest is required. Laboratories sufficient water are required for mixers, loaders, performing ChE assays must be approved by the applicators, and flaggers202 handling pesticides in California State Department of Health. Category 1 or 2 who work for more than 30 hours Closed mixing and loading systems are in any 30-day period. Contaminated equipment or required202 to prevent exposure to concentrates work clothing may not be taken home by em­ caused by spills in the course of pouring. Ground ployees. In addition, minimum amounts of water and aerial application tanks must have an external are required at work sites, along with soap and means for determining the internal liquid level, or towels, for routine or emergency washing. the filler hose must have an automatic shut-off Mixers, loaders, applicators, and flaggers han­ device to prevent overfilling. Such transfer hoses dling Category 1 or 2 pesticides202 must be pro­ must be equipped with a device to prevent vided daily by the employer with clean outer dripping from the outlet end after filling. In addi­ clothing. Contaminated clothing must be im­ tion, no unshielded flexible hoses carrying liquid mediately removed. Mixing and loading sites must pesticide may pass through the driver’s compart­ have at least one change of clean outer clothing. ment of an application vehicle. The employer is required to provide respiratory If employees have not received training previ­ and other personal protective equipment, to clean ously, employers must instruct employees202 on theit as necessary, and to provide new respirator filter safe handling of pesticides used, including personal pads and cartridges according to the manufac­ protective equipment, common poisoning symp­ turer’s instructions. Employees who service or toms, the necessity for eating and smoking rules, repair mixing, loading, or application equipment availability of emergency medical treatment, and must be informed of the hazards associated with the rationale for biologic monitoring. Close super­ exposure to residues and must be provided with vision is required during training. suitable protective equipment and clothing by their Employers must make prior arrangements for employer. emergency medical services and must take an em­ Subsequent to the issuance of the above regula­ ployee to a physician immediately “when the em­tions in 1974, the California State Department of ployer has reasonable grounds to suspect a pesti­ Health sought to guide physicians providing medi­ cide illness or when an exposure to a pesticide has cal supervision in the selection of blood ChE test- ing intervals.203 The table (XIV-1) was provided in a letter to physicians with the caveat that im­ mediate testing was indicated in the event of ac­ cidental exposure from splashes, spills, or other mishaps. Only workers exposed to Category 1 or 2 pesticides for 30 hours or more in a 30-day period were covered. TABLE XIV-1 RECOMMENDED FREQUENCY OF CHOLINESTERASE TESTING IN NUMBER OF WEEKS BETWEEN ROUTINE TESTS, CALIFORNIA STATE DEPARTMENT OF HEALTH, MAY 1975 Work Activity Days of Exposure/Week 2 Days or Less 3 Days or More Mixer-Loader* 2 1 Ground applicator 4 2 Agricultural pilot 4 3 Flagger 4 2 *When closed mixing and loading systems are used exclu­ sively, increase the interval between ChE tests by 1 week for this group. Adapted from Kahn [203], XV. APPENDIX VII SUMMARY OF PERTINENT STATE (EXCLUDING CALIFORNIA) PESTICIDE REGULATIONS

Of the 53 administrative units within the United but in a few administrative units they are made the States and its possessions, all except Guam have at responsible governmental authorities to control the least one law relating to the control of pesticides. use of pesticides and to license or certify custom The laws of Nebraska and American Samoa are or private applicators of pesticides. quite general, without specific provisions in the In 22 administrative units other than California, law. In all other administrative units except the law gives to the responsible authority the Michigan, the law or laws give to the responsible power to require reports of illness due to ac­ governmental authority powers to regulate storage, cidental exposure to pesticides. These administra­ transportation, and disposal of pesticides, to tive units are: Alaska, Arkansas, Colorado, restrict the uses of pesticides, and to hold discipli­ Florida, Hawaii, Indiana, Iowa, Louisiana, Missou­ nary hearings on alleged infractions of regulations ri, Nevada, New Mexico, North Dakota, Ohio, on the use of pesticides. In 35 of the 53 adminis­ Pennsylvania, Rhode Island, South Carolina, South trative units, the responsible authority is given the Dakota, Texas, Vermont, Virginia, Virgin Islands, power to license dealers in pesticides. In 49 ad­ and Washington. This power generally has been ministrative units, the responsible authority licen­ available for only a short time in the administra­ ses or certifies custom applicators of pesticides; in tive units other than California, where it has ex­ 35, the responsible authority also certifies private isted since the passage of the Injurious Materials users of pesticides for the use of restricted-use Law in 1949. California has, therefore, a particu­ pesticides. larly extensive, but not necessarily complete, in­ In most of the administrative units, the responsi­ ventory of illnesses due to pesticides. ble authority is a governmental department, most In general, the various administrative units have commonly the Department of Agriculture or its no statutory authority to require information on equivalent. Departments of Environmental Protec­ the use of pesticides. In Maine, New Hampshire, tion or Conservation are designated as the respon­ and Rhode Island, however, the law provides that sible authorities in several administrative units. renewal of licenses or certifications requires full Other governmental entities (Department of Natu­ reporting of pesticide usage during the previous ral Resources, Department of Health, State period of licensing or certification. A number of Clinics, and Director of Regulatory and Public the other administrative units do have a means for Service Programs of Clemson University) appear obtaining approximations of such information occasionally as responsible authorities. Thirty-nine through requiring use or purchase permits for administrative units provide for Pesticide Boards, pesticides. Maine, New Hampshire, and Rhode Councils, or Committees. In most cases, these ad­ Island have this mechanism as a check on the ministrative units have advisory capacities only, required reporting of use of pesticides.

91 XVI. TABLES

93 TABLE XVI-1 Ethyl parathion Phosphemol Etilon Phosphenol PHYSICAL PROPERTIES OF TECHNICAL Folidol Phosphostigmine GRADE PARATHION Fosferno RB Fosfex Rhodiatox Chemical names Phosphorothiotic acid, 0,0-diethyl Fosfive SNP O-(P-nitrophenyl) ester, 0,0-diethyl Fosova Stabilized ethyl parathion O-p-nitrophenyl phosphorothioate, 0,0-diethyl 0-(4-nitrophenyl) thio- Fostern Sulphos phosphate, diethyl p-nitrophenyl Genithion T-47 thionophosphate Kolphos Tiofos Common names Parathion or ethyl parathion Kypthion Thiophos Form and color Liquid, straw-yellow or amber Lirothion Thiophos 3422 Odor Pungent, -like Metacide Tox 47 Molecular weight 291.3 Murfos Vapophos Molecular formula C10H14N05PS Adapted from the Registry of Toxic Effects of Chemical Boiling point 375 C at 760 mmHg Substances [204], Melting point 6.1 C (freezing point) TABLE XVI-3 Vapor pressure 0.003 rnmHg at 24 C Specific gravity 1.27 at 25 C OCCUPATIONS WITH POTENTIAL Viscosity 15.30 cp at 25 C EXPOSURE TO PARATHION Solubility Parathion is miscible with acetone, alcohol, benzene, CC14, CHC13, Aerial application personnel Flaggers ethyl acetate, o-dichloro-benzene, Area cleanup crews Ground applicator toluene, . Bagging machine operators vehicle drivers Parathion is slightly soluble in kero­ Janitorial personnel sene, petroleum ether, other paraf- Basic manufacturing finic solvents. employees Laundry workers Parathion is relatively insoluble Haulers of Laundry Maintenance personnel (very slightly soluble) in water — Drum fillers Mixer and blender 24 (n) g/ml at 25 C. Drum reconditioning operators (formulators, Conversion factors 1 ppm = 11.9 mg/cum personnel “swampers”) (25 C; 760 mg Hg) 1 mg/cu m = 0.084 ppm Dump personnel Refuse haulers Adapted from [3, 54, 56, 198], Field checkers Tractor tank loaders Field workers (exposed to Truck loaders TABLE XVI-2 “residues” on fruits, Warehouse personnel vegetables, foliage, etc.) SYNONYMS, INCLUDING TRADE NAMES, FOR PARATHION TABLE: xvi-4 AAT Niran PULMONARY VENTILATION RATES AATP Nitrostigmine FOR VARIOUS WORK LEVELS Alkron Niuif-100 Metabolic Level Minute Volume Aileron Nourithion (liters) American Cyanamid 3422 Oleofos 20 Bladan F Oleoparathion Sleep 6.0 Corothion Orthophos Rest 9.3 Corthione PAC Light work 19.7 Danthion Paramar 50 Medium work Diethylparathion Paraphos 29.2 DNTP Parathion-ethyl Medium heavy work 40 E605 Parawet Heavy work 59.5 Ecatox Pestos Plus Maximum work 132.0 Ekatox Pethion Derived from [199]. Ent 15,108 Phoskil 95 TABLE XVI-5 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE INHIBITION IN DOGS FOLLOWING 4-HOUR INHALATION EXPOSURES TO PARATHION Parathion Ct Toxic Cholinesterase, % of normal Concentration (mg min/ Signs (avg of 4 dogs) Mortality (mg/cu m*) cu m) Time RBC Plasma (24-hour) 37.1* 8912 4 hours 73 20 0/4 24 hours 45 8 48 hours 78 16 7 days 65 38 14 days 85 76 8.93 2143 Lacrimation 4 hours 64 14 0/4 occurred in 24 hours 42 7 1 of 4 dogs 48 hours 37 7 7 days 27 21 14 days 37 32 3.42 821.0 4 hours 71 23 0/4 24 hours 44 13 48 hours 39 4 7 days 19 9 14 days 24 30 0.145 34.8 4 hours 70 40 0/4 24 hours 56 20 48 hours 57 17 7 days 57 28 14 days 60 37 0.015 3.672 4 hours 62 18 0/4 24 hours 49 14 48 hours 44 15 7 days 72 35 14 days 58 75 * Average of 2 chamber samples collected at 1 and 2 hours.

96 TABLE XVI-6 PROBIT ANALYSIS OF ERYTHROCYTE (RBC) CHOLINESTERASE INHIBITION IN RATS FOLLOWING 4-HOUR INHALATION EXPOSURES TO PARATHION Percent RBC Bliss Statistical Analysis Parathion Cholinesterase ------Dose Inhibition Cholinesterase Dose 95% Confidence Limits (mg/cu m) (34 rats) Inhibition, % (mg/cu m) Lower Upper 0.04 7 16 0.38 0.17 0.83 0.21 8 50 5.43 4.20 7.03 0.24 28 84 78.20 26.43 231.34 0.83 17 0.91 8 1.21 11 2.17 30 2.27 60 Probit Y = 4.369 + .859 Log X 12.8 58 19.1 69 26.1 85 31.4 80 35.0 68 Blood sampled 24 hours postexposure.

TABLE XVI-7 PROBIT ANALYSIS OF PLASMA CHOLINESTERASE INHIBITION IN RATS FOLLOWING 4-HOUR INHALATION EXPOSURES TO PARATHION Percent Plasma Bliss Statistical Analysis Parathion Cholihesterase------Dose Inhibition Cholinesterase Dose 95% Conlidence Limits (mg/cu m) (34 rats) Inhibition, % (mg/cu m) Lower Upper 0.04 0 16 0.51 0.51 1.18 0.21 0 50 7.28 5.24 10.12 0.24 24 84 103.85 27.23 396.05 0.83 37 0.91 12 1.21 0 2.17 28 2.27 58 Probit Y = 4.257 + .862 Log X 12.8 69 19.1 52 26.1 58 31.4 77 35.0 74 Blood sampled 24 hours postexposture. 97 TABLE XVI-8 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY IN RATS EXPOSED BY INHALATION TO PARATHION AEROSOLS FOR 4 HOURS Percent Cholinesterase Activity from Start of Exposure Concentration* 4 Hours 24 Hours 48 Hours 168 Hours 336 Hours (mg/cu m) RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma 0.04 84 100 93 100 91 100 91 100 83 100 0.21 67 81 92 100 100 100 98 100 70 100 0.24 100 80 73 76 86 80 100 76 74 67 0.83 66 63 83 63 66 76 74 90 85 69 0.91 100 88 92 88 81 68 88 81 77 74 1.21 100 100 89 100 79 100 80 100 95 100 2.17 84 65 70 72 69 69 74 74 78 71 2.27 56 52 40 42 72 68 78 81 53 50 12.8 66 48 42 31 46 44 60 73 61 67 19.1 43 47 31 48 18 59 49 60 78 78 26.1 24 33 15 42 42 38 46 64 58 58 31.4 42 40 20 23 19 27 57 67 74 63 35.0 44 24 32 26 27 28 49 61 60 77 * 34 rats exposed/concentration level.

TABLE XVI-9 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY IN MALE RATS EXPOSED BY INHALATION TO PARATHION AEROSOLS FOR 7 HOURS/DAY, 5 DAYS/WEEK, FOR 6 WEEKS Parathion Percent Cholinesterase Activity from Start of Exposure Concentration 1st Week 2nd Week 3rd Week 4th Week 5th Week 6th Week (mg/cu m) RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma 0.01 88 96 93 100 — — 69 97 70 77 97 99 0.10 57 99 60 66 — — 65 79 67 92 Exposure terminated 0.74 58 68 50 67 24 23 33 21 16 34 26 40 Percent Cholinesterase Activity —Postexposure Period 0.01 82 97 84 127 — — 94 99 —— 119 141 0.10 61 116 76 133 82 119 — — 81 113 — — 0.74 44 113 _ _ 65 100 — — — — 88 117

98 TABLE XVI-10 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY IN MALE DOGS EXPOSED BY INHALATION TO PARATHION AEROSOLS FOR 7 HOURS/DAY, 5 DAYS/WEEK, FOR 6 WEEKS Parathion Percent Cholinesterase Activity from Start of Exposure Concentration Day 1 1st Week 2nd Week 3rd Week 4th Week 5th Week 6th Week (mg/cu m) RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma 0.001 101 88 135 88 129 96 106 95 —— 135 102 135 91 0.01 124 113 106 92 79 70 86 72 — — 97 72 101 58 0.20 89 46 75 41 54 26 74 35 — — 57 53 41 36 Percent Cholinesterase Activity — Postexposure Period 0.001 — — 95 99 95 79 — — 86 97 90 131 98 103 0.01 — — 98 91 104 91 0.20 — — 77 72 61 94 — — 86 115 84 134 79 112

TABLE XVI-11 RAT 24-HOUR LD50 FOLLOWING ORAL ADMINISTRATION OF PARATHION IN CORN OIL Parathion Percent Bliss Statistical Analysis (95% Confidence Limits) Dose Mortality Percent Dose Lower Limit Upper Limit (mg/kg) (10 rats/dose) Mortality (mg/kg) 10.0 100 16 5.72 5.01 6.53 7.9 80 50 6.85 6.18 7.60 6.3 20 84 8.21 7.17 9.40 5.0 10 4.0 0

TABLE XVI-12 DOG 24-HOUR LD50 FOLLOWING ORAL ADMINISTRATION OF PARATHION IN CORN OIL Parathion Percent Bliss Statistical Analysis (95% Confidence Limits) Dose Mortality Percent Dose Lower Limit Upper Limit (mg/kg) (4 dogs/dose) Mortality (mg/kg) 20.0 100 16 4.42 1.29 15.07 15.8 75 50 8.27 4.79 14.29 10.0 50 84 15.50 6.61 36.34 6.3 50 2.5 0

99 TABLE XVI-13 RAT ACUTE ERYTHROCYTE (RBC) ChE50 FOLLOWING ORAL ADMINISTRATION OF PARATHION Percent RBC Bliss Statistical Analysis (95% Confidence Limits) Parathion Dose Inhibition Percent Dose Lower Limit Upper Limit (mg/kg) (10 rats/dose) Inhibition (mg/kg) 0.18 8 16 0.410 0.318 0.527 0.35 13 50 2.579 2.117 3.141 0.70 27 84 16.236 11.716 22.499 1.40 32 2.80 52 5.60 70 7.00 69

TABLE XVI-14 RAT ACUTE PLASMA ChE50 FOLLOWING ORAL ADMINISTRATION OF PARATHION Percent Plasma Bliss Statistical Analysis (95% Confidence Limits) Parathion Dose Inhibition Percent Dose Lower Limit Upper Limit (mg/kg) (10 rats/dose) Inhibition (mg/kg) 0.18 0 16 0.622 0.416 0.930 0.35 9 50 2.546 2.123 3.054 0.70 23 84 10.424 5.813 18.692 1.40 45 2.80 34 5.60 78 7.00 75

TABLE XVI-15 DOG ACUTE ERYTHROCYTE (RBC) ChE50 FOLLOWING ORAL ADMINISTRATION OF PARATHION Percent RBC Parathion Bliss Statistical Analysis (95% Confidence Limits) Dose Inhibition Percent Dose Lower Limit Upper Limit (mg/kg) (4 dogs/dose) Inhibition (mg/kg) 10.0 73 16 0.114 0.032 0.412 2.50 64 50 1.497 1.060 2.115 1.26 50 84 19.619 6.620 58.141 0.50 29

100 TABLE XVI-16 DOG ACUTE PLASMA ChE50 FOLLOWING ORAL ADMINISTRATION OF PARATHION Percent Plasma Bliss Statistical Analysis (95% Confidence Limits) Parathion Cholinesterase------Dose Inhibition Percent Dose Lower Limit Upper Limit (nig/kg) (4 dogs/dose) Inhibition (mg/kg) 10.0 65 16 0.020 0.000 0.893 2.50 59 50 1.670 0.942 2.960 1.26 40 84 141.422 4.061 4,294.465 0.50 42

TABLE XVI-17 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY IN MALE RATS DOSED ORALLY WITH PARATHION 5 DAYS/WEEK FOR 6 WEEKS Percent Cholinesterase Activity from Start of Exposure Daily Dose 1st Week 2nd Week 3rd Week 4th Week 5th Week 6th Week (mg/kg) RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma

0.05 85 98 95 127 — — 119 133 — — 115 156 0.10 87 106 79 20 — — 78 94 —— 81 115 0.25 74 103 — — 66 106 44 1 15 57 54 46 52 Percent Cholinesterase Activity —Postexposure Period 0.05 85 96 0.10 119 109 141 1 17 — — 72 103 ———— 0.25 44 76 69 101 — — 68 106 — — 159 119

TABLE XVI-18 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY IN MALE DOGS DOSED ORALLY WITH PARATHION 5 DAYS/WEEK FOR 6 WEEKS Percent Cholinesterase Activity from Start of Exposure Daily Dose 1st Week 2nd Week 3rd Week 4th Week 5th Week 6th Week (mg/kg) RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Plasma RBC Pla^.m

0.05 82 44 105 68 — — 101 87 — — 83 54 0.10 73 24 86 32 — — 81 44 — — 80 61

0.50 74 22. 65 37 — — 51 80 — — 42 15 Percent Cholinesterase Activity - Postexposure Period

_ — 0.05 70 74 95 92 101 99 — — ——

— — 0.10 77 165 90 94 91 90 — — — —

0.50 50 70 49 90 — 68 93 — — 67 74

101 TABLE XVI-19 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY RECOVERY IN MALE RATS FOLLOWING A SINGLE ORAL DOSE (2.8 mg/kg) OF PARATHION *lme Percent Residual Cholinesterase Activity (Postexposure) ------Hours RBC Plasma 4 44 35 24 45 49 48 56 52 72 51 85 168 60 70 336 67 89

TABLE XVI-20 ERYTHROCYTE (RBC) AND PLASMA CHOLINESTERASE ACTIVITY RECOVERY IN MALE DOGS FOLLOWING A SINGLE ORAL DOSE (2.5 mg/kg) OF PARATHION Time Percent Residual Cholinesterase Activity (Postexposure) Hours RBC Plasma 24 36 41 264 53 78 360 58 85 696 67 117 864 89 112

102 * U.S. GOVERNMEKT PAINTING OFFICE: 1977— 7 5 7 - 0 5 7 / 5 7 3 9 DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE PUBLIC HEALTH SERVICE

CENTER FOR DISEASE CONTROL

NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH

ROBERT A TAFT LABORATORIES

4'576 COLUMBIA PARKWAY. CINCINNATI. OHIO 45226 POSTAGE a n d f e e s paio

„ ______U.S. DEPARTMENT OF H.E.W.

HEW 399 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. $300

DHEW (NIOSH) Publication No. 76-190