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31st January 01:20
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http://www.jamaicaobserver.com/lifestyle/html/20070324T230000-0500_120798_OBS_HEAVY_METAL_POISONING__PART_II____HEALTH_EFFECTS_OF_MERCURY_.asp
Heavy metal poisoning (Part II) - Health effects of mercury Sunday, March 25, 2007 MERCURY is the most toxic non-radioactive element on earth. The term "mad as a hatter" is linked to the madcap milliner in Lewis Carroll's book, Alice in Wonderland. The origin of the saying relates to a disease peculiar to the hat-making industry in the 1800s. A mercury solution commonly used during the process of turning fur into felt caused the hatters to breathe in the fumes of this highly toxic heavy metal. This situation was exacerbated by the poor ventilation in most of the workshops. This, in turn, led to an ac***ulation of mercury in the workers' bodies, resulting in symptoms such as trembling ("hatters' shakes"), slurred speech, loosening of teeth, loss of coordination, memory loss, depression, irritability and anxiety. Hence the term "The Mad Hatter Syndrome". Mercury is receiving considerable attention today because of its ubiquity as an environmental pollutant. The metal is generated naturally in the environment from the degassing of the earth's crust, from volcanic emissions, forest fires and the evaporation of seawater. Mining operations, paper industries and chloralkali plants are significant producers of mercury. Up until 1990, mercury compounds were added to paint as a fungicide; these compounds are now banned. However, surfaces painted with these old supplies still exist. The substance continues to be used in thermometers, thermostats, and dental amalgam. It is also found in many commonly available products including pesticides, fertilisers, auto exhaust, bleached flour, processed foods, drinking water, adhesives, food preservatives and batteries. Medicines, such as mercurochrome and merthiolate contain mercury. Mercury contained in medical, household, and industrial products is able to enter the atmosphere when the products, are discarded, especially when they are incinerated. Mercury is constantly cycling through the environment, evaporating into the atmosphere and returning to the ground as the result of gravity or precipitation and being deposited into lakes and rivers. An estimated two-thirds of mercury in the environment is the result of human activities. Effects of mercury Pure elemental mercury is a ***ulative heavy-metal poison that is moderately absorbed through the skin, poorly absorbed through the gastrointestinal tract, and readily absorbed as vapour through the lungs. The element is strongly toxic when absorbed as vapour from the respiratory tract, but it is considerably less so when exposure occurs via other routes. Elemental mercury often passes through the GI tract without being absorbed; in the past mercury was used for mechanical relief of intestinal obstructions. Compounds of mercury tend to be much more toxic than the element itself, and organic compounds of mercury are often extremely toxic. Mercury damages the central nervous system, endocrine system, kidneys, and other organs, and adversely affects the mouth, gums, and teeth. Exposure over long periods of time or heavy exposure to mercury vapour can result in brain damage and ultimately death. Mercury and its compounds are particularly toxic to foetuses and infants. Women who have been exposed to mercury in pregnancy have given birth to children with serious birth defects. Some of the toxic effects of mercury are reversible. However, heavy or prolonged exposure can do irreversible damage, particularly in foetuses, infants, and young children. Mercury exposure in very young children can have severe neurological consequences, preventing nerve sheaths from forming properly. Mercury poisoning in the young is suspected as a possible cause of autistic behaviour. Methylmercury & fish One of the other forms of mercury is an extremely toxic substance - methylmercury. It dissolves easily in water and bioac***ulates in the food chain. ( Bioac***ulation is the increase in concentration of a substance along the food-chain ). Methylmercury is ingested by fish when it gets in the water then it bioac***ulates in fish. This fish is in turn eaten and can cause many health problems when people eat the mercury contaminated fish. One of the main sources of mercury poisoning is eating methylmercury-contaminated fish. For these reasons, pregnant women and small children should be especially aware of fish advisories in their area. Thimerosal Thimerosal, a preservative that contains mercury, had been added in very minute amounts to vaccines to prevent their deterioration. It has been hypothesised that there could be a potential relationship between thimerosal use in vaccines and neurodevelopmental disorders of autism, attention deficit hyperactivity disorder (ADHD), and speech or language delay. This hypothesis was based on a comprehensive review of the scientific literature on mercury toxicity. At present, all routinely recommended vaccines for Jamaican and American infants are available only as thimerosal-free formulations, with the exception of inactivated influenza vaccine. Dental amalgam Mercury fillings, also known as "amalgam" or "silver fillings," are the most common fillings in the world. They are called silver because of their colour and contain 45 to 52 per cent mercury. The remaining volume is made up with copper, tin, silver and zinc.Exposure to mercury fillings results in a chronic toxicity, not acute poisoning. It has been theorized that amalgam fillings could be part of the explanation for the explosion of learning problems and autism in children since World War II, a time period corresponding with the introduction and widespread use of mercury amalgam. Charles Williamson, MD, co-director of the Toxic Studies Institute in Boca Raton, Florida, states: "Once mothers realise the fillings in their teeth damage the development of their babies' brains while they're in the womb, and once these women understand this damage can result in low IQ, learning and behavioural problems after birth, then we'll see a public outcry against the use of mercury amalgam." Studies in both animals and humans have confirmed the presence of mercury from amalgam fillings in tissue specimens, blood, amniotic fluid, or urine. The American Dental Association ( ADA ) acknowledges that amalgam contains mercury and reacts with other substances. However, to date the ADA maintains that amalgam continues to be a safe material. Of interest, the metallic mercury used by dentists to manufacture dental amalgam is shipped as a hazardous material to dental offices. Treatment To treat patients for mercury overload, doctors recommend a variety of nutrients and drugs to chelate the mercury out of the body. In the process the cells are protected from the effects of the large amounts of free mercury being released into the bloodstream for urinary excretion. Chelation was first used in the 1940s by the United States Navy to treat lead poisoning and was subsequently approved by the Food and Drug Administration as a safe method of treating heavy metal toxicity. Chelation therapy is a medical treatment that improves metabolic and circulatory function by removing toxic metals and abnormally located nutritional metallic ions from the body. It is accomplished by the administration of chelating agents. Dr Jacqueline E Campbell is a family physician in private practice. E mail drjcampbell14@yahoo.com |
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