Mercury is a hazardous chemical and is a naturally occurring element found in air, water and soil with little amount. It can exist in three forms, including elemental (metallic) mercury, inorganic mercury compounds and organic mercury compounds. Elemental mercury is a shiny, silver-white liquid metal and easy to vapourize at room temperature. Inorganic mercury compounds take the form of mercury salts, which are generally in white powder or crystals, with the exception of mercuric sulfide (cinnabar) which is red. Microorganisms can convert inorganic mercury into organic mercury compounds, such as methylmercury which is the most common organic form of mercury found in the environment.
Mercury is used widely in measuring instruments (thermometers and blood pressure instruments), electrical and electronic appliances (thermostats), dental amalgam, and the manufacture of chlorine and caustic soda. It was formerly used in cosmetics, traditional medicines, pesticides and the extraction of gold.
Health effects of mercury
Acute poisoning may result from inhalation of elemental mercury vapour with high amount, or from accidental ingestion of mercury or its salts. Owing to their corrosive nature, it can cause inflammation and necrosis of the oropharynx. Other common symptoms are nausea, vomiting, abdominal pain, bloody diarrhea and renal damage. Exposure of high level of mercury can be fatal.
Chronic exposure to mercury can cause numbness and gradual decreases in the senses of touch, vision, hearing and taste. Progressive loss of memory and balance, insomnia, hand tremors and behavioural changes are common symptoms of its neurological effects. In addition, kidney damage can result in oedema, particularly in the ankles and legs.
Mercury and its compounds are eliminated gradually in urine and faeces. The average half-life of mercury in human is about 60-70 days. However, both elemental and organic mercury can be readily cross the blood-brain barrier and the placenta to foetus, and be excreted in breast milk. In fact, effects of neurological disorder could be irreversible and long lasting. Children and foetuses are more susceptible to mercury poisoning than adults.
How can one reduce the risks of exposure to mercury?
Management of Mercury Poisoning
Laboratory tests are available to measure the amount of mercury in blood or urine. For cases with elevated mercury levels and clinical symptoms and signs, further investigation and in-patient management may be required. Chelating therapy may be indicated in some cases.
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