Estrogenic Activity Profiles of River Water in Kobe, Japan Assessed by In Vitro Bioassay and Chemical Analysis

Abstract

In order to investigate the estrogenic activity profiles and quantitatively characterize the substances contributing to estrogenic activity in the river, biological and chemical analysis were applied to river water extracts. Water samples were collected throughout one year at upstream, midstream and downstream locations of the Akashi River system in Kobe, Japan. The highest estrogenic activity in river water was observed at site A-3 (5.13 × 10^-12 M estradiol equivalent concentration (EEQ)) in Akashi River, which had inflow of discharge effluent from a sewage treatment plant (ESTP) immediately at the upper stream. Results of LC-MS analysis and E-screen assay from samples of A-3 and ESTP demonstrated that estrogens and estrogenic activities detected in site A-3 originated from ESTP. Of the three estrogens and six xenoestrogens analyzed in this study, di (2-ethylhexyl) phthalate (DEHP) and bisphenol A (BPA) were detected in almost all the samples but the calculated EEQ values from these xenoestrogens were below the detection limit of the bioassay. Estrone (E1) was found at sites A-2, A-3 and ESTP, while E2 was found at site A-3 and ESTP. These estrogens (E1 and E2) are the major substances contributing to the estrogenic activity of the samples. However, the EEQ values determined by E-screen assay were lower than those calculated from LC-MS analysis. In consideration of the former reports, the estrogenic activity of river water may be suppressed by estrogen antagonists. Furthermore, the estrogenic activity observed in site I-1 may be affected by some unknown chemicals in the effluent from landfill (EL).