Establishment of reentry intervals for organophosphate-treated cotton fields based on human data: I. Ethyl-and methyl parathion

In each of two studies, two human volunteers entered methyl- or methyl-ethyl parathion-treated cotton fields for 30-minute periods at 0, 12, 24, 48, and 72 hours after treatment; foliage residues, and skin, clothing, inhalation, and biomedical data were obtained. The hands are probably the greatest source of absorbed pesticide chemical while the respiratory system is an insignificant source. Trousers collect the largest amounts of residue but the residue on them does not necessarily undergo absorption by the skin. There is not any evidence of plasma- or red-cell cholinesterase depression or a detectable amount ofpara-nitrophenol, following one-day, single, 30-min exposure. It is estimated that an individual can absorb up to 6.0 milligrams of parathion from cotton 24 hours after treatment with parathion and up to 3.0 milligrams 48 hours after such treatment, during an actual 5-hour work day field exposure. Skin-, and clothing contamination data are inadequate bases for evaluating hazard of possible parathion poisoning. Far more useful are measurements of serum parathion, serum-, and cell cholinesterase activities, and urinary excretion ofpara-nitrophenol in exposed individuals.Contribution to Regional Project W-45, Residues of Selected Pesticides-Their Nature, Distribution, and Persistence in Plants, Animals and the Physical Environment. University of Arizona Agricultural Experiment Station journal series, number 1983.