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Occupational exposure of fieldworkers to organophosphate pesticide residues: environmental correlates of hazard.

Spear RC; Popendorf WJ
Proceedings of the VII International Congress of Rural Medicine, September 17-21, Salt Lake City, Utah. International Association of Agricultural Medicine, 1978 Sep; :304-309
The problem of occupational exposure to organophosphate pesticide residues in California was discussed. An overview of the problem of parathion (56382) poisonings in fieldworkers in the State of California was presented. More than 30 incidents of poisoning in California field workers have been recorded. The outbreaks were apparently the result of dermal contact with parathion on crop foliage or the soil and depended on the intensity of parathion use. Attempts to estimate the respiratory and dermal doses received by a typical worker led to the speculation that the observed cholinesterase (ChE) decreases and other symptoms of organophosphate poisoning were due to parathion being degraded to a more toxic product, probably its oxygen analog paraoxon (311455). Studies of the environmental chemistry of parathion were reviewed. These have shown that dislodgeable residues of parathion and other thiophosphate pesticides contain the more toxic oxygen analogs. In the case of parathion the decrease in ChE activity can be correlated with the amount of paraoxon in the residue. Most of the dermal exposure occurs above the waist. These findings are taken as evidence that the high incidence of parathion poisonings in fieldworkers in California is due to dermal exposure to and adsorption of paraoxon from the foliage. Paraoxon has been estimated to be 10 to 50 times more toxic than parathion. Additional studies have suggested that ozone (10028156) may be involved in degrading parathion to paraoxon on foliage covered with dust, but not on clean foliage. Regulatory issues involved in protecting fieldworkers against hazardous exposure to pesticide residues were discussed. It was noted that in setting reentry intervals, usually between 24 hours and 30 days post chemical application, the sensitivity of pesticide residues to environmental factors must be considered.
NIOSH-Grant; Grants-other; Occupational-health; Agricultural-workers; Insecticide-poisoning; Organo-phosphorus-pesticides; Biotransformation; Gases; Enzyme-activity; Skin-exposure; Plant-substances; Regulations
Prev Med & Environmental Hlth University of Iowa Inst/agric Med & Environ Hlth Iowa Oakdale, Iowa 52319
56-38-2; 311-45-5; 10028-15-6
Publication Date
Document Type
Conference/Symposia Proceedings
Funding Amount
Funding Type
Fiscal Year
Identifying No.
Priority Area
Other Occupational Concerns; Grants-other
Source Name
Proceedings of the VII International Congress of Rural Medicine, September 17-21, Salt Lake City, Utah
Performing Organization
University of Iowa, Iowa City, Iowa
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division