Biological monitoring of commercial pesticide applicators for urine metabolites of the herbicide alachlor

Alachlor (2-chloro-2’,6’-diethyl-N-[methoxymethyl] acetanilide), the active ingredient in several trade name herbicides, is absorbed through the skin and readily excreted in the urine as conjugated metabolites. This paper presents the results of a study to measure alachlor metabolites in the urine of commercial pesticide applicators who were applying alachlor to corn and soybean crops under normal work conditions. Three spot urine samples, collected at the beginning and end of the work shift and the morning after the exposure survey, were collected from 20 applicators, 7 hauler-mixers, and 8 controls. Each sample was analyzed using both a competitive, solid-phase, enzyme-linked immunoassay (ELISA) and a high-performance liquid chromatography (HPLC) technique. Although the urine metabolite concentrations measured by ELISA were consistently higher than the respective HPLC measurements, a high correlation (r = 0.90) was observed between the ELISA and HPLC measurements. The controls, with little exposure to alachlor, had metabolite levels below or near the lower limits of detection for each analysis technique. Similar urine metabolite concentrations were observed for the applicators and hauler-mixers, suggesting similar work exposures. The average postexposure urine concentrations were not correlated with the amount of alachlor handled and applied, suggesting that other factors, such as work practices, are greater determinants of absorbed doses of alachlor.