Determination of Estrogenic Substances in the Water of Muko River Using in Vitro Assays, and the Degradation of Natural Estrogens by Aquatic Bacteria

Abstract

In order to determine the level of estrogenic substances in river water and to evaluate the degradation of estrogen by aquatic bacteria, three in vitro assays, E-Screen, Ishikawa cell-alkaline phosphatase (Ishikawa cell-ALP) assay and yeast estrogen screen (YES) assay were used. Water samples were collected throughout one year at upstream, midstream and downstream locations on the Muko River, Hyogo Prefecture, Japan. Estrogenic substances in the water were extracted by solid phase extraction using Sep-pak C18 cartridges. The levels of estrogenic substances in river water changed daily, weekly and monthly. The highest 17β-estradiol equivalent (E2 equivalent) was obtained as 32.9 ng/l at the midstream in July of 2002. Although some differences in E2 equivalent were observed in some water samples between the E-Screen and Ishikawa cell-ALP assays, the levels measured by these assays were generally similar and ranged from not detected (ND) to 32.9 ng/l. E2 equivalent levels assayed by YES were low or below the detection limit. Degradability of estrogen by aquatic bacteria was investigated in the summer and winter. E2 and estrone (E1) were degraded completely within five days in the summer, and within seven days in winter. Bacterial degradation of a synthetic estrogen, 17α-ethynylestradiol (EE2), was much lower compared to that of E2 or E1.