Mercury toxicity in beluga whale lymphocytes: Limited effects of selenium protection

► Both inorganic and methylmercury impaired lymphocyte proliferation. ► Organic Hg was more toxic to lymphocytes than inorganic Hg. ► Selenium provided a partial protection against Hg toxicity. ► Metallothionein levels increased with exposure to organic Hg. ► These Hg-related effects occur at concentrations currently observed in free-ranging beluga whales in the Arctic.