Role of individual susceptibility in risk assessment of pesticides

Objectives-This study presents criteria for assessing the individual pestic ide burden of workers in the chemical industry. Methods-A group of 1003 workers exposed to methylparathion or ethylparathio n (alkyl phosphates), propoxur (carbamate), or cyfluthrin (pyrethroid) was investigated. After exposure to methylparathion or ethylparathion the methy lparathion or ethylparathion and methylparaoxon or ethylparaoxon concentrat ions in plasma, the p-nitrophenol concentration in urine, and the activitie s of cholinesterase and acetylcholinesterase were measured. For exposure to propoxur the propoxur concentration in plasma, the 2-isopropoxyphenol conc entration in urine, and the cholinesterase and acetylcholinesterase activit ies were measured. For exposure to cyfluthrin the cyfluthrin concentration in plasma was measured. Results-At the same propoxur concentration only workers with a low individu al acetylcholinesterase activity reported symptoms. Workers who metabolised cyfluthrin rapidly reported less symptoms than workers with a lower rate o f metabolism. This tendency was also evident in cases of mixed exposure (cy fluthrin and methylparathion). Conclusions-In the assessment of exposure to pesticides susceptibility of t he individual person has to be considered.