PT14 Toxicity of Mixtures
Exhibit Hall
8:00 AM - Tuesday
(PT223) Combination effects of environmental estrogenic compounds on the reproduction of medaka Oryzias latipes.
Watanabe, Naoko1, Ishibashi, Hiroshi1, Hirano, Masashi1, Iwasaki, Yuko1, Matsumura, Naomi1, Shiratsuchi, Hideki1, Takao, Yuji2, Nishimura, Tetsuji3, Arizono, Koji1, 1 Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Japan2 Faculty of Environmental Studies, Nagasaki University, Japan3 National Institute of Health Sciences, Japan
ABSTRACT- The natural steroid estradiol-17beta (E2) and the synthetic estrogens 4-t-octylphenol (OP) and bisphenol A (BPA) have frequently been detected in the aquatic environments. These estrogenic compounds can thus interact with physiological systems and cause alterations in development, growth and reproduction in wildlife. At present, however, no relative potency estimates have been derived for either their mixtures in the reproductive biology. In this study, the combination effects of a mixture of E2, OP and BPA at environmentally relevant concentrations were assessed in a 21-d reproduction assay using medaka (Oryzias latipes). No reproductive impairment of paired medaka showed significant differences in the number of eggs produced and fertility in the treatment groups at the environmentally relevant concentrations (comprising 3.3 ng/L E2, 3.3 microg/L OP and 3.3 microg/L BPA). However, the mixtures at individual no-effect concentrations (comprising 67 ng/L E2, 67 microg/L OP and 1000 microg/L BPA) affected the reproductive impairment (such as reduction of the number of eggs produced and fertility). These results suggest that the ability of each individual estrogenic compound to contribute to the overall effect of a mixture, although a mixture of E2, OP and BPA at environmentally relevant concentrations may not affect the fish population inhabiting various natural aquatic environments.
Key words: Combination effect, Oryzias latipes, Reproduction, Estrogenicity