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تسجيل

Mercury

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  108

2026-09-23

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Mercury

Mercury has been used in the manufacture of thermometers and a range of other scientific instruments for hundreds of years, but this use has now declined. Mercury and its compounds have also been used widely in the chemical industry and in the manufacture of drugs and pesticides. Mercury-containing dental amalgam fillings are still used in many countries. The toxicity of mercury and its compounds is influenced greatly by the chemical form and valence state. The most toxic form of inorganic mercury is its divalent (Hg2 ) salt, particularly mercuric chloride, which was used as a disinfect ant in earlier times. The fatal (oral) dose of mercuric chloride is less than 1 g, which led to its popularity as a homicidal and suicidal poison. There is significant toxicity associated with inhalation of (elemental) mercury vapour, which has a very high vapour pressure at normal room temperature. Broken mercury thermometers can constitute a serious risk in children through inhalation of vapour, particularly in a home environment such as a bedroom (Velzeboer et al. 1997). Organic forms of mercury, such as methyl mercury, are strongly neurotoxic and, being relatively lipid-soluble, can accumulate in fatty tissues of the body such as the brain. Large-scale environmental disasters have occurred, such as that involving the Minimata Bay area in Japan where hundreds of people died or became in capacitated. This was caused by the factory discharge of industrial waste that contained mercury, which settled into the sediments of the bay and river and was methylated by microorganisms. The methyl mercury became incorporated into the fish diet on which the residents of Minimata largely existed, and this resulted in so-called Minimata disease. Mercury poisoning may also be seen after the use of traditional medicines and cosmetics (Weldon et al. 2000). The signs and symptoms of acute and chronic mercury poisoning mainly involve the CNS, kidney or skin. Characteristic symptoms in chil dren include acrodynia (‘pink disease’), which include signs such as pink hands and feet (Velzeboer et al. 1997). Mercury species may be retained in the body for a long time after the cessation of exposure, and blood elimination and urine excretion rates show long half-lives. Mercury may be excreted in the urine for 6–12 months after cessation of exposure, which makes urine measurements an attractive way to assess historical exposure, and analysis of hair can be useful in environmental studies or unusual clinical cases. Mercury from the diet (particularly fish) contributes to the concentration of mercury found in blood, but is usually well within normal limits. However, populations who consume unusually large quantities of certain fish (e.g. swordfish) or of whale meat may accumulate high concentrations of (methyl) mercury (Kales and Goldman 2002). There is some evidence that such exposure presents a serious risk in pregnancy and early child development. Reference values for mercury in non-exposed populations in blood and urine are <4 μg/L and <5 μg/L, respectively.