Mercury poisoning is exposure to harmful amounts of the toxic element, usually by breathing mercury vapors or ingesting compounds containing mercury. Mercury poisoning can permanently damage the nervous system and immune system, as well as the brain, lungs, kidneys, heart, and liver. High–level exposure can be fatal. Developing fetuses are particularly sensitive to mercury poisoning.
Two early descriptions of mercury poisoning were given by German-Swiss physician and botanist Paracelsus (1493–1541), who was also known as Philippus Aureolus Theophrastus Bombastus von Hohenheim, in 1550, who described symptoms of mercury miners in central Europe; and by Italian physician Bernardino Ramazzini, who wrote about the terrible health conditions of mercury miners, gilders (those who apply thin layers of gold to surfaces), and mirror makers. Before, during, and after these times, mercury was often used as an elixir by alchemists, supposedly to provide immortality to those who drank it.
One of the largest modern cases of mercury poisoning occurred in the 1970s when grain was treated with mercury, as a fungicide, and given to Kurdish peasants who were starving in northern Iraq. It is estimated that 6,000 died from ingesting mercury-infected grain while another 100,000 were sickened.
In the 2010s, the use of mercury has been banned by many industries throughout the world; however, it is still commonly used in the production of batteries, cement, explosives, gold, steel, and other products. Although the use of mercury has been phased out or banned in some industries, it is still widely used in the production of gold, tin, cement, steel, batteries, and explosives, and in laboratories and hospitals.
Mercury (Hg) is a naturally occurring element in air, water, and soil. Three forms of mercury pose different potential health hazards:
Because the body cannot easily rid itself of mercury, repeated exposure results in its build up in tissues. Elemental mercury vapor and methylmercury are the most dangerous forms because they readily reach the brain. Most humans have trace amounts of methylmercury in their bodies. Methylmercury crosses the placenta to the developing fetus, whose red blood cells can have mercury concentrations that are 30% higher than those of the mother. It also passes to the newborn child through breast milk. Fetuses, infants, and young children are significantly more sensitive to the effects of mercury than are adults. During the 1950s, large amounts of organic mercury were dumped in Japan's Minamata Bay, killing some 1,000 people and causing severe nervous system damage in unborn children. Thus, mercury poisoning is sometimes called fetal Minamata Bay disease. Mercury poisonings have also occurred from eating meat from animals fed contaminated grain.
In 2012, the Food and Drug Administration (FDA) warned consumers not to buy skin products that contain mercury. Its report Mercury Poisoning Linked to Skin Products, published March 6, 2012, stated that certain skin creams, beauty and antiseptic soaps, and lotions, such as those that lighten the skin and anti-aging products that remove age spots, come into the country illegally or are brought into the United States from travelers to other countries. Many of these products contain mercury. The FDA states that it “does not allow mercury in drugs or in cosmetics, except under very specific conditions, which these products do not meet.” The FDA recommends that consumers check the labels of such products for the words “mercurous chloride,”“calomel,”“mercuric,”“mercurio,” or “mercury.” If labels or ingredients are not present on the product, then do not use it, and do not use products that are labeled in languages other than English.
The prevalence of mercury poisoning in American children is hotly debated but is generally considered to be rare. Fish and shellfish contaminated with methylmercury are the major sources of mercury poisoning in the United States and around the world. A 2009 study by the U.S. Centers for Disease Control and Prevention (CDC) on the exposure of children to elemental mercury found that the largest exposures to mercury were from children stealing mercury from a school or industrial site. The vast majority of elemental exposures:
Some of the most serious outbreaks of mercury poisoning have occurred in Japan and Iraq. For instance, large outbreaks of methylmercury poisoning (poisoning from mercury and chlorine) occurred in Japan between 1953 and 1965, Iraq from 1971 to 1972, and Ghana and Pakistan in 1969. The consumption of grains and fish contaminated with mercury are two high risk ways of getting mercury poisoning in these countries.
The risk of mercury poisoning also rises when gold rises in price as it has done for many years. This occurs because gold miners often have to separate mercury from ore in which gold is present in a process called gold-mercury amalgam. As the beginning of the 2010s, it was estimated that about 15 to 20 million gold prospectors are active in over 60 countries of the world, especially those of South America, Asia, and Africa. The January 3, 2011 Yale University report Threat of Mercury Poisoning Rises with Gold Mining Boom states: “Today's small-scale mining industry is motivated less by adventure than survival. Poverty-driven miners rely on inexpensive, outdated, polluting technologies and chemicals—chief among them mercury—with heavy costs for human health and the environment.”
The most common cause of mercury poisoning is eating fish and shellfish contaminated with high levels of methylmercury. Less common causes of mercury poisoning include:
The same level of mercury vapor can result in higher mercury concentrations in children than in adults, because children have larger lung surface areas for their body weight. Furthermore, since mercury vapors are denser than air, there are higher levels closer to the ground where children breathe in the vapors. Although elemental mercury vapor is only slowly absorbed through the skin, it can irritate the skin and eyes and cause contact dermatitis. Touching or swallowing elemental liquid mercury is usually not harmful because it rolls off the skin and very little is absorbed by the gastrointestinal tract.
The effects of mercury exposure depend on a variety of factors including the
Symptoms of elemental mercury poisoning appear within a few hours of exposure to high levels of vapor. Smaller amounts inhaled daily cause symptoms that develop over time. Symptoms can include:
Unlike elemental mercury, inorganic and organic mercury are absorbed through the intestinal tract, although a swallowed battery may pass harmlessly through a child. Symptoms of inorganic mercury poisoning include:
Methylmercury can interfere with the neurological development of fetuses, infants, and children, causing the following:
Symptoms of organic mercury poisoning most often develop over years or decades and include:
The diagnosis of people with mercury poisoning includes a complete physical examination, medical tests, and diagnostic procedures.
The child's vital signs—including temperature, pulse, breathing rate, and blood pressure—will be monitored. Important diagnostic information includes:
The following procedures are commonly used to diagnosis mercury poisoning:
Treatment can include traditional methods, including drugs and alternative methods.
Although inhaled elemental mercury poisoning can be difficult to treat, possibilities include:
Inorganic mercury poisoning is treated with supportive measures, including possibly intravenous fluids and electrolytes. Others include:
Treatment for methylmercury poisoning depends on the severity and is similar to treatments for cerebral palsy. It may include fluids and electrolytes and kidney dialysis.
Chelators—drugs that bind mercury and other heavy metals—may be required for weeks or months to remove mercury from the blood and protect the kidneys and brain. Other medications to treat mercury poisoning include:
There are various alternative types of chelation therapy. These include bentonite clay baths and combinations of herbs, amino acids, and other nutritional supplements.
The American Association of Poison Control Centers (AAPCC) should be called for instructions: (800) 222–1222. The AAPCC is a national voluntary health organization that represents 57 poison centers across the United States. According to the website of the AAPCC, the organization is “dedicated to actively advancing the health care role and public health mission of our members through information, advocacy, education and research.” The AAPCC sets standards for poison center operations and certifies specialists in poison information. These professionals are available around the clock seven days a week to respond to all types of emergency requests relating to poisonings. In addition, the AAPCC maintains the only poison information and surveillance database in the United States, what is called the National Poison Data System.
The prognosis for mercury poisoning can include the following:
The U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) recommend that young children and women who are pregnant, may become pregnant, or are nursing:
Other preventions for mercury poisoning include:
See also Explosives ; Mercury .
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Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy., N.E., Atlanta, GA, 30341, (800) 232-4636, http://www.atsdr.cdc.gov/ .
Food and Drug Administration, 10903 New Hampshire Ave., Silver Spring, MD, 20993, (888) 463-6332, http://www.fda.gov/ .
National Institute of Neurological Disorders and Stroke, P.O. Box 5801, Bethesda, MD, 20824, (301) 496-5751, (800) 352-9424, http://www.ninds.nih.gov/ .
Occupational Safety and Health Administration, 200 Constitution Ave., Washington, D.C., 20210, (800) 321-6742, http://www.osha.gov/ .
Margaret Alic, PhD
Revised by William A. Atkins, BB, BS, MBA