Heavy Metal Toxicity

Mercury is a highly toxic element and an introduced pollutant in the environment. Though its toxicity risk in highly contaminated areas is well-documented, research has shown that mercury is a threat to human health and wildlife. Its toxic effect depends on its chemical form and the route of exposure. Methylmercury [CH₃Hg] is the most toxic form. It upsets the immune system, modifies genetic and enzyme systems, and harms the nervous system. Exposure to methylmercury is usually by ingestion. Elemental mercury is released from broken thermometers, and can cause tremors, gingivitis, and nervousness if its vapours are inhaled for a long time. Most people are exposed to low levels of mercury, often through chronic exposure; however, some people are exposed to high levels of mercury, including acute exposure in industrial settings. This chapter deals with the sources and routes of exposure to mercury, its aetiology, pathophysiology, clinical manifestations, the mechanisms of mercury toxicity, and toxicological effects of mercury.