The influence of individual susceptibility in pyrethroid exposure

The aim of this study was to find a suitable biomarker for pyrethroid adver se effects. It was shown that there is a correlation between the half-life time (t(1/2)) of pyrethroids in plasma and the clinical findings. We hypoth ized that this finding indicates an interindividual different amount of tot al esterase activity or even a polymorphism. By in vitro experiments it was demonstrated that pyrethroids are cleaved by carboxylesterases. After it t urned out that carboxylesterase activity in human plasma is too low for det ection, a method for specific determination of carboxylesterase activity in human isolated lymphocytes was developed. As a substrate for carboxylester ase activity, cyfluthrin was added to the lymphocyte suspension. As a proof for cyfluthrin degradation by carboxylesterases the produced hydrocyanic a cid was determined by GC/MS. First hints for interindividual differences in carboxylesterase activity in lymphocytes were found. (C) 1999 Elsevier Sci ence Ireland Ltd. All rights reserved.