Organophosphate Pesticide Poisoning

Refer to: Peoples SA, Maddy KT: Organophosphate pesticide poisoning. West J Med 129:273-277, Oct 1978

Organophosphate Pesticide Poisoning STUART A. PEOPLES, MD, and KEITH T. MADDY, DVM, Sacramento, California

A total of 118 workers from a 120-person grape picking crew became ill in early September 1976. Of these (108 men and 10 women), 85 received medical attention and three of the 85 were admitted to hospital. The symptoms were typical for organophosphate poisoning. Average plasma and red cell cholines- terase values for the affected workers were depressed more than 60 percent. Most were treated with atropine and some were also treated with 2-PAM (pralidoxime). The exposure to residues of the organophosphate pesticides dialifor (TorakR) and phosalone (Zolone`) occurred in one grower's vineyards near Madera, California. It appeared that workers had been allowed into recently-treated areas before the expiration of the required 30-day safety interval for dialifor, and that excessive skin exposure to residues of this pesticide had resulted. The clinical management of these cases and the occupational surveillance of the workplace became quite complex. The grower sustained significant losses of grapes during the period in which some of his vineyards were under quarantine and he had to pay substantial medical expenses as well as a fine for violating state regulations concerning the proper use of pesticides. Organophosphate pesticides decay more slowly under hot, dry weather conditions than they do when rainfall is frequent. California has imposed a number of specific safety intervals to be observed after the application of these pesticides to certain crops. If, in violation of these regulations, workers are permitted to enter fields too soon, poisoning can occur.

ON SEPTEMBER 8, 1976, out of a crew of 120 Eighty-five of the ill workers received medical adults (110 men and 10 women), 15 field work- attention, three of these were admitted to hospital. ers became ill while hand-harvesting grapes near The medical treatment included outpatient treat- Madera, California, in vineyards managed by one ment of approximately 60 of the workers by two grower. The following day, 100 additional work- Madera physicians, emergency room treatment of ers became ill; and 3 more on September 10. 25 workers by physicians at Madera Community The symptoms exhibited by the affected work- Hospital, and the admission to hospital of three ers were typical for organophosphate poisoning. of the 25 workers seen in the emergency room. They included weakness, one-sided head pressure, Most of the patients were treated with atropine nausea, vomiting, tight chest and blurred vision. and some were also treated with 2-PAM. Clinical but asthenia From the Worker Health and Safety Unit, California Depatrt- recovery was prompt in most cases, nent of Food and Agriculture, Sacramento. were a in several Presented at the Annual Meeting of the United States PuLblic and other symptoms problem Health Service Professional Association. San Francisco, April a number of weeks. 3-6. 1977. workers for Stubmitted. revised. February 27, 1978. Reprint requests to: Stuart A. Peoples. MD. California Depart- Blood cholinesterase tpsts were conducted on ment of Food and Agriculture. 1220 N Street. Sacramento. CA Plasma and 95814. the workers at the time of treatment.

THE WESTERN JOURNAL OF MEDICINE 273 ORGANOPHOSPHATE PESTICIDE POISONING red blood cell values averaged 60 percent below The high levels of dialifor (Torak') and phos- normal levels. Interviews of all 120 workers alone (Zolone@) residues found on the foliage of showed that 33 of the workers who became ill vines in certain locations did not support the had not sought medical attention; these workers grower's records of application date, volume and had exhibited only mild symptoms of weakness, rate per acre of application for the pesticides in dizziness and blurred vision. All exposed workers question. Comparison of these high residue levels (in addition to those initially treated) were ex- with samples collected in previous years for amined by a physician and received blood tests studies by the University of California and by the as soon as the grower was required to furnish Department indicated either a later date of appli- medical supervision. cation, at least for dialifor, or a higher rate of A Madera labor contractor had provided the application than had been indicated by the grow- crew whose members became ill. The 1976 grape er's records. harvest began approximately two weeks before the first evidence of illness which was suspected Regulatory Actions as being due to exposure to cholinesterase-inhibit- On September 13 an order was issued by the ing compounds. The source of the workers' ex- Department to the grower, prohibiting any of the posure was determined to have been pesticide workers who became ill from returning to the residues in the vineyards of one grower, who unharvested section of the suspect field. farmed approximately 2,300 acres of grapes at On September 15 orders were issued to the several locations southeast of Madera, California. grower and his three labor contractors requiring that any employee hand-harvesting grapes in any Investigation of his vineyards be provided with medical super- On September 10, 1976, the California De- vision. This required medical supervision for all partment of Food and Agriculture (henceforth pickers was to include periodic plasma and red referred to as the Department) was notified of the cell cholinesterase tests and periodic examination illnesses, and personnel were assigned to investi- by a physician to look for signs or symptoms of gate the incident. The Environmental Protection organophosphate poisoning. A prohibition of the Agency, Region IX, the California Department of harvest of grapes at two specific locations was Health, and the California Division of Industrial also included in this same order. Safety (CAL-OSHA) were immediately notified. That same day, the grower obtained the serv- Prior agreement has designated the Department ices of a physician as medical supervisor. On as the primary enforcement agency in this type of September 16 a mobile medical laboratory was occupational exposure incident. set up at the vineyard where harvest was continu- Personnel from the Madera County Agricul- ing, and specimens of the workers' blood were tural Commissioner's Office immediately obtained drawn by a laboratory technician for cholines- grape foliage and fruit samples from the vineyard terase determination. The workers were examined locations where the workers had been harvesting by the medical supervisor. Following these exami- when they became ill. Samples were also taken nations and subsequent ones, the workers were from vineyards that the workers had harvested issued an identification card and were instructed immediately before the onset of their illnesses. to carry it with them. All new workers who were These samples were sent to Department labora- brought in to hand-harvest grapes on the grow- tories for analysis. The Department's two mobile er's other properties also had their blood drawn Pesticide Residue Laboratories were moved to and analyzed for cholinesterase levels; all of Madera to help analyze the large numbers of leaf their cholinesterase enzyme levels were in normal and grape samples that were drawn. Laboratory ranges. None of the new employees became ill or findings of pesticide residues often did not corre- experienced cholinesterase level depression while spond with the grower's pesticide application harvesting. records. Commencing September 17, 1976, personnel The grower's records of pesticide applications from the Department and the Madera County were reviewed to determine the workers' probable Agricultural Commissioner's Office began a daily exposure to pesticide residues before the onset of inspection of the workers entering the vineyards. the illnesses, as well as their possible further ex- The workers' identification cards were checked posure were the harvest allowed to continue. to verify that they were under medical supervision

274 OCTOBER 1978 * 129 * 4 ORGANOPHOSPHATE PESTICIDE POISONING and the workers were observed to be sure that vineyard with a soap and water solution applied they were wearing clean outer clothing at the be- with a motorized pesticide spray rig. In addition ginning of each work day. Workers who had no to this washing, a rainstorm helped to reduce the evidence of being under medical supervision or amount of pesticide residues present, as verified were not wearing clean outer clothing were not by laboratory analysis. On October 5 this order allowed to work. was amended to permit the machine-harvest of The grower and medical supervisor made ar- these grapes remaining under quarantine. Hand- rangements for a medical laboratory technician to harvesting of this vineyard was not permitted due be present on several occasions to draw blood to high residue levels of dialifor still remaining specimens from workers arriving at the ranch for on the foliage, even though residue levels on the the first time for employment as grape harvesters. fruit itself were below the legal tolerance of 1 Several hundred persons who had been harvest- ppm permitted for human consumption of grapes. ing grapes in other locations in the San Joaquin The driver of a machine harvester rides far above Valley were screened in this way on arrival and the grape foliage. none was found to have low cholinesterase levels. Estimates were made of the levels of pesticide The medical supervisor returned to the ranch residues to which the original work crew had been a number of times to examine workers individu- exposed before the onset of the illnesses. These ally for signs of organophosphate poisoning. All estimates were based upon comparison of pesti- depressed cholinesterase levels found in blood cide residue level at the time of sampling, the samples during these follow-up visits were found dates of harvest, and the dates and rates of appli- only in the first work crew of 120 persons who cation with the results of available pesticide resi- had been poisoned and there was no evidence of due degradation studies. further depression in these same workers after Workers had been exposed to foliage contain- the initial exposure. Those workers from the ing up to 57 ppm of phosalone and up to 2.3 ppm initial poisoning episode who were found to have phosalone oxon. Carefully conducted studies of severely depressed cholinesterase levels were or- workers in citrus groves and peach orchards dur- dered by the medical supervisor not to engage in ing the summer seasons of 1974, 1976 and 1977 any activity that would involve substantial body in this same locale did not show significant cho- contact with treated foliage; these employees linesterase depression or illness when workers were assigned to other tasks on the ranch. Those were exposed to levels of phosalone and phosa- workers with moderate cholinesterase depressions lone oxon residues on foliage which were higher were allowed to continue work in those fields than these actually measured levels. Therefore, found to have no residues, or very low residues these levels of phosalone or phosalone oxon (or of organophosphate or carbamate pesticides on both) on grape foliage were not considered to the foliage. present a toxic hazard to persons picking grapes On September 22 the order prohibiting the by hand. harvest of grapes at one location was amended It appears that the workers had been exposed after laboratory tests showed a degradation of the to residues of up to 100 ppm of dialifor and more residue levels on the fruit and foliage. This vine- than 2 ppm of dialifor oxon when working in the yard was released to be hand-harvested. No em- three different locales. These levels of dialifor ployee from the work crew originally poisoned and dialifor oxon were determined to have been was permitted to harvest in this vineyard. On toxic to the workers harvesting these grapes. The October 1 the order issued prohibiting the harvest investigation led to the conclusion that a number of a second block of grapes was amended to per- of rows in several vineyards had apparently been mit the hand-harvesting of a section of this field, treated late in the season, and that probably only with similar restrictions on persons who were al- about half of the required 30-day worker safety lowed to pick. Pesticide residue levels on the fruit interval had passed when workers were exposed and foliage had been found to have decayed to a to the residues of dialifor and dialifor oxon. safe level. Within two weeks after this poisoning incident Subsequent to the initial issuance of an order occurred, foliage and grape samples were col- prohibiting the harvest in a third vineyard the lected from 79 other vineyards that had been grower had attempted to remove some of the resi- treated with dialifor. Blood specimens were col- dues from the fruit and foliage by washing this lected from workers harvesting grapes in these

THE WESTERN JOURNAL OF MEDICINE 275 ORGANOPHOSPHATE PESTICIDE POISONING vineyards. Growers and workers were interviewed quirements; these three vineyards were placed concerning work experience in these other vine- under quarantine. For the vineyards that had yards. No evidence was found concerning adverse foliage with appreciable (but not high) levels of health effects associated with working in these organophosphate residues (previously considered other vineyards. nontoxic for normal workers) the medical super- visor allowed harvest by workers with normal Discussion cholinesterase levels and by some workers with Since 1949 California has had experience with moderate but not severe depression of cholines- poisoning of field workers exposed to residues of terase values. For the workers with severely de- organophosphate pesticides. The state has im- pressed cholinesterase levels, the medical super- posed worker safety reentry intervals for organo- visor permitted work only at jobs that either did phosphates on a number of crops. In most cases not involve contact with foliage or involved pick- when poisoning of this type occurs there usually ing in fields with no organophosphate or carba- is evidence that entry was not in compliance with mate residues present. specified intervals. The Federal Environmental In the process of analyzing the cholinesterase Protection Agency at present is evaluating Cali- level data for workers at the close of the picking fornia's approach to protection of field workers. season on this ranch, it was noted that of the It appears that they may require adherence to originally exposed workers, although further de- safety intervals for more pesticides and crops than pression of the low cholinesterase levels did not are required now and for longer periods than the occur while under medical supervision, the return current average length of 48 hours for the Federal of levels toward normal was slower than consid- Safety Intervals. Many of the required safety in- ered desirable. In retrospect it appears that work- tervals in California exceed seven days. ers with significantly depressed cholinesterase Several recent studies by the Department on levels, but who appear to be clinically normal, foliage residues at the time of harvest, and of should be assigned only to jobs picking crops in blood and urine studies of field workers by the fields where there are no detectable levels of Department and the University of California at organophosphate or carbamate pesticide residues Davis, indicate that almost all growers are adher- or assigned to other jobs where no such exposure ing to prescribed preharvest and worker safety would be expected to occur. If such work could intervals. not be found they should be placed on disability It is significant that several hundred new work- compensation until their cholinesterase levels re- ers brought in from other vineyards in the San turn to normal. Joaquin Valley had normal cholinesterase levels Poisoning of field workers by exposure to pesti- upon arrival at the ranch where pesticide misuse cide residues on foliage in a treated field is not a had led to the above-mentioned poisoning inci- problem commonly diagnosed and reported by dent. During the same month in which this poison- physicians. Most reported occupational exposures ing incident occurred the University of California to pesticides in California occur in persons in- at Davis was in the midst of a study on grape volved in mixing, loading and applying pesticides. pickers. The study was underway in a nearby It is possible that there is some underdiagnosis county in which the rates of organophosphate and underreporting of such incidents. pesticide application for grapes are the highest in Of the 1,746 physicians' reports filed in 1975 the San Joaquin Valley. No depressed cholines- that contained a suggestion of possible pesticide terase levels were noted among these workers. involvement in an occupational exposure, 240 As for the medical management of this specific were classified as involving employed persons who incident, it was determined that most of the work- were exposed to pesticides with no obvious illness ers desired to return to work within a few days of resulting (primarily firemen and policemen), an- the onset of illness and treatment. They wanted other 163 were placed in a category of uncon- to avoid being assigned a lower-paying nonpick- firmed or negative for actual pesticide exposure. ing job or being placed on disability compensa- It appears that about 1,343 of the cases may have tion at a lower rate of pay. The medical supervisor resulted from actual pesticide exposure. Of these, had ordered that the vineyards with high levels 797 were only eye or skin problems; although of foliage residues would not be harvested by these can be very troublesome, they all appear to hand even though the grapes met tolerance re- have been treatable without permanent adverse

276 OCTOBER 1978 * 129 * 4 ORGANOPHOSPHATE PESTICIDE POISONING effects. Only 546 persons developed systemic cide exposure and interfered with the worker's effects attributed to pesticide exposure. This group right to file a claim for workman's disability com- deserves very careful study and attention. Most pensation. of these persons were not ill for more than a few Early in 1977 an inquiry about pesticide poi- days and chronic problems apparently did not soning of workers in general and about this often occur. specific incident was conducted by a committee In 1975, in the category of field workers ex- of the Senate of the California Legislature. Later posed to pesticide residues, there were 28 sys- in the legislative session, a new law (AB 1307) temic, 115 skin, 21 eye, and 3 eye and skin cases was enacted which went into effect in January reported by physicians. Most of the systemic ill- 1978. This new law requires that all suspected nesses occurred as a result of one incident in pesticide illnesses be reported to the county health which the grower allowed citrus harvesters to officer by telephone within 24 hours. In the case pick before the safety interval for ethyl parathion of occupatonal reports, one copy of the Doctor's had expired. In this incident, the grower experi- First Report of Work Injury is to be mailed to the enced crop losses due to the quarantine imposed, county health officer within seven days. Details and paid sizable medical expenses and a fine for of these reporting requirements can be obtained violation of state regulations. from the county health departments. Deaths attributable to occupational pesticide exposure rarely occur in California. Four such Appendix since 1971. In 1972 an Some useful sources of medical information for phy- deaths have occurred sicians about pesticides include the following: applicator in a peach grove became intoxicated from drinking alcoholic beverages while working, Addresses Telephone Numbers spilled some parathion upon himself, and died; a California Department of Health, (415) 843-7900 Pesticide Study Unit Ext. 505 jail trustee working as a gardener drank paraquat 2151 Berkeley Way from an unlabeled wine bottle and died. In 1973 Berkeley, California 94704 a structural pest control worker died and in 1975 California Department of Food and (916) 445-8400 another structural pest control worker died-both Agriculture, Medical Consultant 1220 N Street when cyanide was grossly mishandled and il- Sacramento, California 95814 legally used indoors. In 1974 there were no oc- Donald Morgan, MD (EPA Consultant) (3 19) 353-5558 cupational deaths. (In 1975 in California, there Iowa Epidemiologic Studies Program or 338-8474 attributed to occupa- University of Iowa Medical School were 20. deaths pesticides: lowa City, Iowa 52240 tional, 1; accidental or homicide, 1; homicide, 1, Sacramento Poison Center (916) 453-3692 and suicide, 17. This has been the typical pattern Sacramento Medical Center for pesticide-caused deaths in recent years in 2315 Stockton Blvd. California.) Sacramento, California 95817 San Diego Poison Control Center (714) 291-4000 The large number of acutely ill patients in this University Hospital incident severely taxed the medical resources of 225 W. Dickson Street the physicans involved with the result that they San Diego, California 92103 treat- Los Angeles (Thos. Fleming) (213) 664-2121 directed their attention to giving emergency Poison Center ment which left no time for filling out required Children's Hospital of Los Angeles state forms. This was made increasingly difficult 4650 Sunset Blvd. by the fact that few patients spoke English, and Los Angeles, California 90054 Denver Poison Center (303) 629-1123 that they left after being treated and before the Denver General Hospital physicians could get the necessary information. 301 W. 7th Street The physicians believed that they had neither the Denver, Colorado 80204 for these Chevron Chemical Comp4py (415) 233-3737 time nor facilities locating workers; Research Laboratories therefore, few reports were filed. 940 Hensley Way Concerns were expressed by several groups Richmond, California 94806 representing the workers' interests that the lack Dow Chemical Company (517) 636-4400 2030 Dow Center Road of complete reporting of each case on appropriate Midland, Michigan 48640 forms separately to the Division of Industrial Shell Chemical Company (415) 837-1531 Safety and to the Department of Health allowed 2401 Crow Canyon Road or 837-3120 for continued underreporting of this type of pesti- San Ramon, California 94583

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