The hazards of organophosphorus (OP) pesticides to agricultural workers are reviewed. Restrictions implemented by the Department of Labor for Guthion (86500), Trithion (786196), Systox (8065483), Disyston (298044), EPN (2104645), methyl-parathion (298000), Phosdrin (7786347), Azodrin (6923224), parathion (56382), Dimecron (13171216), and tetraethyl-pyrophosphate (107493) (TEPP) are discussed. The mechanism of OP poisoning is described; it is primarily due to acetylcholinesterase inhibition that results in accumulation of acetylcholine (ACh) within the body. The ACh accumulation produces a classical cholinergic syndrome. Acute dermal toxicity ranges from 2.4 milligrams per kilogram (mg/kg) for TEPP to 230mg/kg for EPN. Episodes of mass agricultural worker poisonings are cited for some pesticides, including parathion, ethion (563122), and Guthion. Dissipation and degradation of OP pesticides are assessed. Some degradation products are less toxic than others. The hazards of worker contact to OP pesticide residues on foliage from inherent dermal and oral toxicity are stressed. It is estimated that several hundred thousand agricultural workers are potentially exposed to OP pesticide residues on crops every year. About 120 to 200 pesticide deaths per year are estimated, based on a pesticide morbidity reporting system. Actual numbers may be higher; the true extent of pesticide related death and illness is not known. An improved reporting system for pesticide accidents is suggested. Proposed strategies to provide protection to exposed workers include biological controls, substitutions of pesticides that are not ACh inhibitors, shorter lived pesticides, encapsulated pesticides, better protective clothing, improved personal hygiene, mechanical harvesters, use of decontamination agents, and establishment of field reentry safety intervals. The author concludes that the greatest cooperation is necessary between OSHA, NIOSH, and the Environmental Protection Agency to provide adequate protection for exposed workers while producing minimum disruption in agriculture.
NIOSH, U.S. Department of Health, Education, and Welfare, 17 pages, 8 references