ABSTRACT
Concern over the possibility of hormonal systems being disrupted by chemicals in the environment has led to the development of assays to detect such chemicals. Technical and formulated deltamethrin, a widely used synthetic pyrethroid pesticide, was screened for (anti)estrogenic and (anti)androgenic activities by means of two major in vivo short-term screening tests: the uterotrophic and Hershberger assays. The results reported here indicate the absence of in vivo (anti)estrogenic and (anti)androgenic activities for both technical and formulated deltamethrin at the dose levels tested (2.0 and 4.0 mg/kg/day). However, further tests, including in vitro screening assays, are required to characterize fully the lack of endocrine action of these chemicals.