Evaluation of estrogenic activity of organic biocides using ER-binding and YES assay

Biocides have been used not only in everyday items such as clothes, kitchenware, daily necessities, and infant utensils, but also in cosmetics and wrapping papers for foodstuffs. Since there is a high possibility of exposure to biocides from such materials, their safety must be assessed adequately using a range of methods. We investigated the estrogenic activity of 20 organic biocides using two in vitro screen assays: estrogen receptor (ER) binding assay and yeast estrogen screen (YES) assay. Twelve of the biocides were positive in the ER-binding assay. Regardless of the presence or absence of rat S9Mix for metabolic activation, 4-chloro-3-methylphenol was positive in both ER-binding and YES assay. 4-Chloro-3,5-dimethylphenol was positive in the ER-binding assay and showed a pseudopositive manner in the YES assay that was observed the dose-independent estrogenic activity at only one dose point. Hiba oil was positive in the ER-binding assay but was positive in the YES assay only in the presence of rat S9Mix. These results suggest that ER-binding and YES assay could be adapted for evaluation of the endocrine-disrupting activity of biocides. The biocides found to be positive in vitro now require assessment by in vivo screening methods.