Sequential cholinesterase tests and symptoms for monitoring organophosphate absorption in field workers and in persons exposed to pesticide spray drift

The Washington aerial spray drift study: Children's exposure to methamidophos in an agricultural community following fixed-wing aircraft applications

“…Pesticides become airborne during and after aerial and ground applications, sometimes resulting in significant offtarget pesticide movement and potential exposure to workers and individuals near sprayed fields (Richter et al, 1986(Richter et al, , 1992. Distance from source, wind direction, and wind speed have been identified as primary determinants of off-target movement (Barnes et al, 1987;Richards et al, 2001).…”

Pesticides and Human Health

“…Dermal absorption of drift may contribute to community exposures, and for evaluation of community exposure, monitoring of respirable residues is important in the research setting (WHO, 1993a). In agricultural communities little studies have been done to evaluate routes of exposure to communities exposed through skin and by aerosol inhalation to drift from adjacent fields, although some studies suggest significant systemic absorption of pesticides, resulting in ChE depression, among persons in such communities under selected conditions (Richter et al, 1986). The provision of dermal absorption data is required for the registration of agrochemicals, particularly in USA (Scott et al, 1992).…”

“…Both the parent compound and the oxon can undergo a series of detoxication reactions that are mediated by various A-esterases (paraoxonase, carboxyesterase), by P450, and by glutathione transeferases. The leaving group, p-nitrophenol in the case of parathion, which is also generated by hydrolytic cleavage, and alkylphosphates are excreted in the urine and can be quantified as an index of OPs exposure (Richter et al, 1986). For occupational exposures, pesticides are unusual in that dermal residues are often the most important source of systemic absorption.…”

“…OPs such leptophos, EPN, cyanofenophos, trichloronate and salithion proved to cause irreversible ataxia in chicken, mice and sheep and their AChE inhibition stands for their acute toxicity, while NTE inhibition is responsible for their paralytic ataxia and can be used as a standard screening method for delayed neuropathy (El-Sebae et al, 1981). The precise measurement of ChE (erythrocyte or plasma) can be useful as a measurement for low level exposure to OPs in epidemiological research (Richter et al, 1986, Dyer et al, 2001). Recent studies conducted have shown that lower group mean plasma and erythrocyte ChE level in populations living adjacent to cotton fields which are sprayed regularly with OPs (Richter et al, 1986).…”

“…The precise measurement of ChE (erythrocyte or plasma) can be useful as a measurement for low level exposure to OPs in epidemiological research (Richter et al, 1986, Dyer et al, 2001). Recent studies conducted have shown that lower group mean plasma and erythrocyte ChE level in populations living adjacent to cotton fields which are sprayed regularly with OPs (Richter et al, 1986). Also, urinary alkylphosphates are sensitive indicators of OPs exposure, and have been shown to correlate with symptoms.…”