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Harm of Methylmercury

    Harm of methylmercury to humans include paresthesia, loss of coordination, speech difficulties, reduced vision, hearing impairment, blindness, and even death.


    Ingested methylmercury is easily fully absorbed by gastrointestinal tract. It binds primarily to free cysteine and proteins and peptides containing this amino acid. Methylmercuric-cysteinyl complexes are identified as methionine that transports proteins in the body. Because of this similarity, methylmercury can be transported freely through the body, including across the blood-brain barrier and the placenta, where it is absorbed by the developing fetus. In addition, methylmercury readily binds to proteins, so methylmercury is not easily eliminated. Methylmercury has a half-life of about 50 days in human blood.

    The fetus is most susceptible to mercury. Exposure to methylmercury in utero can adversely affect a baby's developing brain and nervous system. The main health effects of methylmercury are impaired neurodevelopment. Therefore, cognitive thinking, memory, attention, language, fine motor, and visuospatial skills may be affected in children exposed to methylmercury during fetal life.

    Several studies have linked methylmercury to developmental defects in fetuses in the womb, such as reduced IQ and language skills, and memory function and attention deficits. Adult exposure to methylmercury also increases the risk of cardiovascular disease, including heart attacks. Some evidence also suggests that methylmercury may cause autoimmune effects in sensitive individuals. Although some people have proposed a link between methylmercury and autism, there is little data to support such a link.

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