Early life-stage mortality in zebrafish (Danio rerio) following maternal exposure to polychlorinated biphenyls and estrogen

In the present study, specific polychlorinated biphenyl (PCB) congeners were examined far embryo and early life stage mortality in zebrafish (Danio rerio). A set of eight PCBs and two hydroxylated PCBs and 17 beta-estradiol were tested. Of the compounds tested, 4'-OH-PCB30 (hydroxylated polychlorinated biphenyl) and PCB 104 were found to be highly toxic to embryos following maternal exposure and transfer to the oocyte. It was also observed that 17 beta-estradiol exposure resulted in a high incidence of embryo mortality. Analysis of estrogen receptor levels during embryonic development showed increased mRNA (ribonucleic acid) levels from the 1K stage to 50% epiboly. Following injection of the different compounds, the estrogen receptor mRNA levels were also analyzed in adult male fish to determine if there was a correlation between embryo mortality and estrogenicity of the studied PCBs. The two PCBs that were highly embryo toxic were observed to be estrogenic.