Mercury and selenium bioaccumulation in wild commercial fish in the coastal East China Sea: Selenium benefits versus mercury risks.

This study investigated the contents of total mercury (THg), methylmercury (MeHg) and selenium (Se) in 22 fish species and 10 invertebrate species from the coastal East China Sea. The THg and MeHg contents were significantly higher in benthic fishes. Both Hg and Se biomagnified in the food webs, with evidences of associations during trophic transfer. In addition, Se:Hg molar ratio and Se health benefit value (HBV) were used as novel criteria for Hg exposure risk assessments, showing that Se presented in molar excess of Hg in all samples, which would negate the risks of Hg toxicity. HBV provided more informative results than Se:Hg molar ratio, pointing to possibly lower health risks for some fishes containing high levels of Hg and Se. Although the HBV results challenge the traditional Hg health risk assessment, its future application still requires worldwide comprehensive investigations.