Organophosphate Pesticide Poisoning
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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.