Field reentry, pesticide exposure

Dermal Exposure Levels. Setting acceptable maximum dermal exposure levels to specific pesticides has been difficult. This is primarily due to a lack of specific data on dermal transport rates for specific pesticides as related to adverse effect levels and presumed no-effect levels. We are now requiring such data from the registrants, and our Department has a suggested protocol (1) that is offered to registrants that will provide such information from animal exposure studies. This dermal transport rate information is important in setting minimum field reentry intervals for field workers as well as in evaluating exposure levels of mixers, loaders, and applicators. 

The following are some of the data that may be required by CDFA to assist in making exposure estimates of persons involved in various activities involving the use of pesticides indoor exposure field reentry mixer, loader, and applicator exposure, dermal absorption, and dermal dose response data. 

Reentry intervals are now established on the basis of (1) data on dermal absorption or dermal dose response (2) inhalation, dermal, and oral acute toxicity studies in animal models (3) foliar and soil residue dissipation data and, (4) available human exposure data. CDFA recommends several sources as useful guides for determining residues of pesticides on soil and leaf surfaces (dislodgeable residue) and conducting field reentry studies involving human volunteers (1-5). Human exposure studies may not be required if adequate animal data from (1) through (3) above are... 

W.J. Popendorf, Advances in the unified field model for reentry hazards, in Dermal Exposure Related to Pesticide Use Discussion of Risk Assessment, ed. R.C. Honeycutt, G. Zweig, and N.N. Ragsdale, ACS Symposium Series 273, American Chemical Society, Washington, DC, pp. 323-340 (1985). 

The Department has developed methods for monitoring the exposure of workers exposed to organophosphate and carbamate pesticides. These methods utilize the determination of plasma and red blood cell cholinesterase activities and urinary alkyl phosphates. Studies are reported vrti ich show that these methods have proven useful in evaluating the safety effectiveness of closed-transfer systems and in determining reentry times for field workers. 

Scott RC, Ramsay JD (1987) Comparison of the in vivo and in vitro percutaneous absorption of a lipophilic molecule (cypermethrin, a pyrethroid insecticide). J Invest Dermatol 89 142-146 Serat WF (1973) Calculation of a safe reentry time into an rachaid treated with a pesticide chemical which produces a measiuable physiological response. Arch Environ Contam Toxicol 1 170-181 Serat WF, Bailey JB (1974) Estimating the relative toxicologic potential of each pesticide in mixture of residues on foliage. Bull Environ Contam Toxicol 12 682-686 Serat WF, Mengle DC, Anderson HP, Kahn E (1975) On the estimation of worker entry intervals into pesticide treated fields with and without the exposure of human subjects. Bull Environ Contam Toxicol 13 506-512... 

---