Mercury, a heavy metal, is toxic to human beings. High levels of exposure to mercury can result in devastating mental and physical effects. In the United States, the chief risk of exposure to mercury is from the consumption of certain types of fish and shellfish, although mercury poisoning also can result from exposure in the air or in other areas of the environment.
Mercury in Food
Methylmercury, an organic form of mercury present in some seafood, is highly toxic to humans, and ingestion of the poison or even direct contact with the skin can cause side effects, especially for young children and unborn babies. The Food and Drug Administration advises pregnant women not to eat specific varieties of fish, including swordfish, shark, tilefish and king mackerel, to avoid exposing their unborn babies to potential mercury poisoning.
Symptoms of methylmercury poisoning might show up in the nervous system and brain, resulting in attention disorders, language problems, memory deficits and reduced fine-motor skills. A child exposed to mercury while in the womb also could have severe birth defects.
Affected children and adults could experience sensation disturbances in their extremities and in their lips and mouths, reduced peripheral vision, muscle weakness that could affect walking and talking, and hearing impairment.
Mercury in the Environment
Mercury, inherent in some elemental metals, acts as a toxin to humans when it is present in the air they breathe, allowing the poison to be absorbed through lung tissue. Mercury is also found in some carbon fuel sources, including coal and crude oil. When refined, it can escape into the air as an environmental toxin.
Symptoms of exposure to elemental mercury in high levels include uncontrollable muscle tremors, moodiness, anxiety, irritability and even pronounced shyness. In addition, a toxic level of elemental mercury in the body can cause insomnia, reduced cognitive function, weakness and muscle wasting, and unexplained headaches.
Other Mercury Compounds
Less common sources of mercury exposure can occur during the mining of gold. Even volcanoes and forest fires can spew mercury into the atmosphere. While most rocks and soil contain trace amounts of mercury, heavy accumulations pose the greatest risk. Inorganic forms of mercury, such as mercury chloride, mercury cyanide or mercury salts, can also cause problems when they are absorbed through the skin or ingested.
Toxic symptoms include irritation and damage to the skin or to the eyes through direct contact, or lung and throat damage from inhaling mercury compounds in the air.
Chronic exposure to mercury also could result in reduced fertility, kidney damage, personality changes and increased skin sensitivity, in addition to similar symptoms caused by methylmercury and elemental mercury.
