Monitoring study of urinary metabolites and selected symptomatology among Florida citrus workers.

A cross-sectional monitoring study was made of citrus fieldworkers employed during an entire citrus growing season in Florida. A survey questionnaire was administered to 1811 fieldworkers employed as applicators, mixers, loaders, tractor drivers, general combination workers, and pickers on 436 citrus groves throughout Florida. The study was designed to evaluate exposure to organophosphorus pesticides by analyzing the urine of citrus fieldworkers for dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP), dimethyl dithiophosphate (DMDTP), diethyl phosphate (DEP), diethyl thiophosphate (DEPT), and diethyl dithiophosphate (DEDTP), and to relate the findings to the reported occurrence of selected health symptoms associated with pesticide intoxication. Urine samples were collected for analysis from 332 spray-season workers and 265 harvest-season workers. Measurable DEP residue values were found in 68% of the spray season workers and 43% of the harvesters. However, with the exception of DEP and DETP values in the urine of spray-season workers, metabolite residues were low, often at, or just above, detection limits (which were usually 0.02 ppm but occasionally rose higher, with a few at 0.03 ppm and a very few at 0.04 ppm). Although there was clearly exposure to organophosphates among the citrus fieldworkers, there was no apparent association between the reported health symptoms and the relatively low levels of organophosphate metabolites found in the urine of the workers.