Susceptibility of male and female Japanese medaka (Oryzias latipes) to 2,4,6-trichlorophenol-induced micronuclei in peripheral erythrocytes

2,4,6-trichlorophenol (2,4,6-TCP) is a widespread probable human carcinogen and has been proven to have genotoxicity in in vitro assays. However, little genotoxicity information and no micronuclei induction data for 2,4,6-TCP is available from in vivo tests, especially for sex-specific differences. Following a preliminary test, a piscine peripheral erythrocyte micronucleus assay was conducted on medaka (Oryzias latipes) after a 28-day exposure to 2,4,6-TCP. In the present study, the mean micronuclei (MNC) frequencies of all of the groups increased in a dose-dependent manner, which indicated the potential genotoxicity of 2,4,6-TCP. Moreover, males were found to be more susceptible compared with females after a 28-day exposure to 2,4,6-TCP in all of the dosed groups above 10 μg·L⁻¹. This is the first report on the potential of micronuclei induction and a sex-susceptible effect in the peripheral erythrocytes of mature fish after 2,4,6-TCP in vivo exposure.