The chemical form of mercury in fish

摘要

The primary dietary source of neurotoxic mercury compounds is via the ingestion of methylmercury species accumulated in fish. Methylmercury from fish has been linked to neurological damage (Minamata disease) and increased risk of myocardial infarction. Despite its importance, the complete chemical identity of the mercury coordination in animal tissue remains unknown. The toxic properties of any element are critically dependant on molecular form; for example, dialkylmercury derivatives are toxic atsuch low levels that they are considered supertoxic, whereas mercuric selenide has a relatively low toxicity and accumulates as an apparently benign detoxification product in marine mammals. Knowing the chemical nature of a potential toxicant is, thus, essential to understanding its toxic properties. Mercury is very flexible in its coordination of nonmetallic elements, with structurally characterized species exhibiting coordination numbers between two and eight. X-ray absorption spectroscopy (XAS) is ideally suited to identification of chemical forms in situ, but it previously has not been much applied to molecular toxicology.