The potential for oestrogenic effects of pesticides in headwater streams in the UK

Abstract Twenty-six pesticidal compounds and samples of stormwater from two different agricultural catchments were screened for oestrogenic activity using an in vitro recombinant yeast-based assay. Only six fungicides showed an oestrogenic response with low comparative biological activity of 5000 to 2.5 million times less potent than 17β-estradiol (E2), a natural steroidal oestrogen. Concentrations of biological activity expressed as E 2 equivalents for the headwater stream stormwater samples ranged from