Evaluation of reproductivity of medaka (Oryzias latipes) exposed to chemicals using a 2-week reproduction test

Effects of endocrine disrupting chemicals on reproductive ability of medaka (Oryzias latipes) were investigated. Exposure of male medaka to estrogenic chemicals such as 17β-estradiol (E2), p-nonylphenol (NP), 4-t-butylphenol (BP) and bisphenol-A (BPA) caused a decrease in the numbers of eggs hatched rather than those of eggs spawned, which seemed to be affected by estrogen-like effects of these chemicals. Exposure of female medaka to E2 and NP reduced the numbers of eggs spawned rather than those of eggs hatched. The concentrations at which reproductivity of female decreased (E2:0.1 nmol/L, NP:0.03 μmu;mol/L) were lower than those of male (E2:3 nmol/L, NP:μ>0.3 μmu;mol/L). Diethylhexyl phthalate, benzophenone and tributyltin chloride did not affect reproductivity. In this study, adverse effects of estrogenic chemicals on reproductivity of medaka could be detected, so the materials and methods used in this study were considered to be able to be applied for a screening test method.