Mercury

Mercury and mercury compounds including methylmercury and mercuric chloride are environmental contaminants that have toxic effects upon human health. Owing to its properties of preventing fungal and mildew growth, mercury is a component of products such as paints, batteries and grain fungicides. When these and other mercury-containing products such as thermometers are disposed of, or in the case of fungicides when they are used on grain products, mercury can contaminate the soil, water and air. In addition, acid rain is another source of environmental mercury contamination.

Mercury is a potent central nervous system toxin capable of causing a wide spectrum of mental disorders and is also a potential carcinogen.

One of the greatest concerns for human health is the bioconversion by microorganisms in soil and water of inorganic mercury into methylmercury, a highly toxic form of this metal that is rapidly absorbed by the body. Among dietary sources, contaminated fish is the largest source of mercury exposure since methylmercury accumulates in aquatic species. Freshwater fish tends to have slightly higher levels than marine water fish as the selenium concentrations in marine water offer partial protection against mercurys effects. Among the fish varieties most contaminated with methylmercury are pike, trout and bass (freshwater varieties) and shrimp, snapper and halibut (marine water varieties), species that are towards the top of the aquatic food chain.

In addition to dietary sources, individuals living near incineration, waste disposal or recycling facilities or mercury production plants are at greater risk for mercury exposure through environmental contamination. Dental amalgams contain mercury and therefore are another possible source of exposure; dentists and dental assistants may be exposed to higher than average levels of this toxic compound on a daily basis.

While there is limited evidence of carcinogenicity for mercuric chloride in animals, there is sufficient evidence in animals to support the carcinogenicity of methylmercury compounds and therefore they are considered to be possibly carcinogenic to humans. Additionally, mercury compounds have been found to be potent neurotoxins affecting the central nervous system, capable of causing emotional disturbances, mild tremors, dementia and other symptoms in adults (the phrase mad as a hatter reflects the development of mental disorders that occurred in hat makers due to their exposure to mercury which was used to process felt material for hats).

Young children and fetuses are very sensitive to the nervous system manifestations, with the later capable of experiencing severe brain damage upon exposure to mercury compounds transferred across the placenta. Mercuric chloride can cause gastrointestinal effects such as ulcerative colitis and kidney damage and has been found to disrupt immune system function.

In addition to dietary sources, individuals living near incineration, waste disposal or recycling facilities or mercury production plants are at greater risk for mercury exposure through environmental contamination. Dentists and dental assistant may be exposed to higher than average levels of this toxic compound on a daily basis because of the mercury in dental amalgams. Young children and fetuses are very sensitive to the nervous system manifestations of mercury poisoning, with the later capable of experiencing severe brain damage upon exposure to mercury compounds transferred across the placenta.

One of the greatest concerns for human health is the bioconversion by microorganisms in soil and water of inorganic mercury into methylmercury, a highly toxic form of this metal that is rapidly absorbed by the body. Among dietary sources, contaminated fish is the largest source of mercury exposure since methylmercury is biomagnified in aquatic species. Freshwater fish tends to have slightly higher levels than marine water fish as the selenium concentrations in marine water offer partial protection against mercurys effects. Among the fish varieties most contaminated with methylmercury are pike, trout and bass (freshwater varieties) and shrimp, snapper and halibut (marine water varieties), species that are towards the top of the aquatic food chain. Dental amalgams contain mercury and therefore are another possible source of exposure.

While there is limited evidence of carcinogenicity for mercuric chloride in animals, there is sufficient evidence in animals to support the carcinogenicity of methylmercury compounds and therefore they are considered to be possibly carcinogenic to humans. Additionally, mercury compounds have been found to be potent neurotoxins affecting the central nervous system, capable of causing emotional disturbances, mild tremors, dementia and other symptoms in adults (the term mad as a hatter reflects the development of mental disorders that occurred in hat makers due to their exposure of mercury used to process felt material for hats). Mercuric chloride can cause gastrointestinal effects such as ulcerative colitis and kidney damage and has been found to disrupt immune system function.