The role of biotransformation in organic mercury neurotoxicity.

Although the clinical patterns of organic and inorganic mercury poisoning are very different, systemic toxicity experiments have shown that the histological changes in the kidneys and dorsal root ganglia neurones are identical with the 2 classes of compounds. It has been further suggested that the toxicity of organic mercurials is the result of biotransformation to inorganic mercury. To test this hypothesis, between 10(-7) and 10(-10) mol of mercuric chloride and methyl mercuric acetate were injected directly into the cerebrum of rats. The comparative size of lesions was estimated anatomically and by reference to blood brain barrier dysfunction. Inorganic lesions were only slightly larger than those produced by equimolar amounts of organic mercury. Consequently both organic and inorganic mercury must be regarded as neurotoxic in their own right. Conversion of organic mercury certainly occurs but is not the only mechanism by which organic mercury exerts its toxicological effect.