Hazards of Mercury contamination on health and environment
Mercury is a ubiquitous environmental toxin and a hazardous metal that occurs naturally in the earth’s crust. It is an element which cannot even remove in water by boiling. . Three forms of mercury (elemental, inorganic, and organic) exist, and each has its own toxicity. , mercury and its compounds found in all environment including ambient air, surface and drinking-waters, soil and sediments, biota, food and the occupational environment. Natural phenomena such as erosion and volcanic eruptions, and anthropogenic activities like metal smelting and industrial production may also lead to substantial contamination of the environment with mercury. According to United States “Environmental Protection Agency” mercury is emitted worldwide in the range of 5,000 to 8,000 metric tons per year. From the atmosphere, mercury cycles from rainwater into lakes and oceans, where it is converted by microbial activity into organic methyl mercury. When the term “methyl mercury compounds” was introduced as a medical subject heading, the U.S. National Library of Medicine has listed approx 1,000 publications on experimental toxicology of this substance. At present, methyl mercury has become one of the environmental pollutants. 116
It is a neuro, nephro, and immunotoxic, it transport into tissues, crosses the blood-brain barrier and also crosses the placenta. Methyl mercury accumulates in aquatic food chains and has greater potential toxicity than inorganic mercury. Methyl mercury concentrates in fish, then birds and mammals, including humans, who eat those fishes as a source of food by the consumption of mercury in food induce many diseases and mortality including central nervous system defects and erethrism, arrhythmias, cardiomyopathies, and kidney damage have been associated with mercury exposure. When these fishes consumed by pregnant women may lead to neurodevelopmental problems in their developing fetus, such as mental retardation, vision, hearing loss, and language disorders. Necrotizing bronchitis and pneumonitis arising from inhalation of mercury vapors results in respiratory failure, very high mercury exposure causes paraesthesia ataxia, sensory abnormalities, depression and other neuropsychiatric disorders in adults. Elemental mercury vaporizes at room temperature, these elemental mercury vapors easily passes through pulmonary alveolar membranes through inhalation and enter the blood, where it distributes primarily to the red blood cells, central nervous system, and kidneys. Mercury salts are also hazardous and toxic to the kidneys, causing acute tubular necrosis, immunologic glomerulonephritis, or nephrotic syndrome.
Wildlife exposes to mercury and methyl mercury from a different environmental sources such as mine tailings, industrial effluent, agricultural drain water, impoundments, and atmospheric deposition from electric power generation. Terrestrial and aquatic life may be at risk by the exposure to waterborne mercury and methyl mercury, which accumulates in successive tropic levels in the food chain. If high tropic level feeders, such as piscivorous birds and mammals, ingest sufficient methyl mercury in prey and drinking water, mercury toxicoses occur, including damage to the nervous, reproductive, excretory systems .
Mercury is used in gold mining to extract gold from ore during this process mercury evaporates, these vapors of mercury in the air around amalgam burning sites are alarmingly high and almost always exceed the World Health Organization (WHO) limit for public exposure. These exposures affect not only the workers but also those in the communities surrounding the processing centers. According to WHO the inhalation of mercury vapors produce harmful effects on the digestive, nervous, immune systems, kidneys, lungs and may be fatal, Current studies indicate that those people who are working in the ASGM (Artisanal and small-scale Gold Mining) communities experience neurological effects, kidney effects, and possibly immunotoxicor autoimmune effects from mercury exposure. Elemental mercury in liquid form is found in thermometers, barometers, and other instruments. Dental amalgam, a composite metal that is about 50% mercury, used to fill decayed teeth, Fluorescent light bulbs and disk batteries also contain mercury, indiscriminate disposal of these items is a major source of environmental mercury contamination when they are buried in landfills or burned in waste incinerators rather than recycled. EPA (Environmental Protection Agency) is working with the National Institute of Standards and Technology and stakeholders to reduce the use of mercury-containing non-fever thermometers in industrial setting. Mercury salts are very toxic to the kidneys, causing acute tubular necrosis, immunologic glomerulonephritis, or nephrotic syndrome. Central neuropathy can also occur from mercury salt exposure. Methyl mercury has been used as a fungicide on seed grains. When grain accidentally treated with a mercury fungicide causes food poisoning.
In conclusion mercury contamination in environment are increasing day by day this could be a major health hazard, Mercury and their compound produce adverse health effect on a global scale, fish is an essential part of our lives and if it contaminated with mercury then it is possible that mercury would spread to human so there should be international action to reduce the contamination of mercury or substituting it with safer alternatives, and control anthropogenic releases of mercury from activities such as manufacturing, mining, and power production. Governmental and non-governmental organizations must make a turn in their approach and apply informative and educational programs, as well as make pragmatic decisions aimed at reducing mercury burden both nationally and internationally.