Arsenic in water supplies
Arsenic is a naturally occurring, poisonous metallic element that poses significant health risks when present in drinking water supplies. Found in various forms, including inorganic and organic compounds, arsenic can enter water through both natural processes like weathering and human activities such as mining and industrial pollution. Groundwater sources typically have the highest concentrations of arsenic, which can lead to chronic health conditions like arsenicosis, a disease marked by skin deformities and increased cancer risk. This issue disproportionately affects marginalized communities in developing countries, where access to testing facilities and safe water is limited. The World Health Organization has established a permissible limit for arsenic in drinking water of 10 micrograms per liter, a standard that is often not met in affected regions. Contaminated water sources have been identified in various countries, including India, Bangladesh, and the United States. Efforts to mitigate arsenic contamination include using adsorbents like clays and iron salts, which can help reduce arsenic levels in water. Understanding the prevalence and effects of arsenic in water is crucial for public health, particularly in vulnerable populations.
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Arsenic in water supplies
DEFINITION: Poisonous, crystalline metallic element
Ubiquitous in nature, arsenic represents a major health threat to human water supplies and foods, especially in the world’s poorest countries.
Arsenic is naturally brittle and relatively soluble in water. It is found activated in the owing to a combination of natural processes (weathering, biological activity, and volcanic eruptions) and human activities. In some cases, arsenic is naturally present in aquifers. It is also associated with geothermal waters, and its presence has been reported in several areas with hot springs. Human beings have played a significant role in increasing the rate of natural mobilization of arsenic through activities such as mining, combustion of fossil fuels, and the use of arsenic in pesticides, herbicides, crop desiccants, and food additives. Industrial effluents add to the environmental availability of arsenic. Even though human use of arsenic has been significantly reduced since the mid-twentieth century, the impacts of arsenic on the environment are likely to continue for some time.
Arsenic is found in various forms and is a major constituent of more than two hundred different minerals. Some of the elements with which arsenic often forms compounds are oxygen, chlorine, tungsten, tin, molybdenum, cadmium, sulfur, lead, silver, iron, and even gold. Arsenic is widely found in ores such as arsenopyrite.
Contamination of drinking water is one of the most significant ways in which arsenic threatens human health. Four types of arsenic compounds commonly exist in water: arsenite and arsenate, which are inorganic arsenic compounds, and methyl arsenic acid and dimethyl arsenic acid, which are forms of arsenic. The amount of arsenic present in drinking water varies among different local water sources, which include (rivers, lakes, reservoirs, and ponds), (aquifers), and rainwater. Of these, groundwater contains the highest concentrations.
Long-term to this metal results in chronic arsenic poisoning, or arsenicosis. Prolonged exposure to arsenic causes various types of cancer; other common health effects include diabetes mellitus, hypertension, and respiratory diseases. Particularly in the world’s poorest nations, people suffering from arsenicosis often withdraw from society, as the disease causes a deformation of the skin that is difficult to differentiate from leprosy. Arsenicosis caused by contaminated drinking water affects the poor more often than it affects the rich.
Because arsenic is carcinogenic, the World Health Organization has set a standard for the amount that is permissible in drinking water that is deemed to be safe. The original standard was 50 micrograms per liter, but the amount was reduced in 1993 to 10 micrograms per liter; in most developing countries that are plagued by the problem of arsenic contamination, however, the higher level is still allowed, in part because of a lack of testing facilities.
Arsenic contamination of water supplies is relatively site-specific and affects a limited number of people who are in proximity to the contaminated water. A number of aquifers across the world have been identified has having arsenic concentrations greater than 50 micrograms per liter; these include aquifers in India, Bangladesh, Taiwan, China, Hungary, Mexico, Chile, Argentina, Thailand, Ghana, Austria, Japan, France, Argentina, New Zealand, and the United States. For a long time, arsenic was not among the list of elements tested by water-quality testing laboratories; thus, scientists have not yet identified all the world’s regions that are vulnerable to arsenic contamination of drinking water.
The of arsenic in natural waters is controlled by solid-solution interaction. The importance of oxides in reducing arsenic concentration in natural waters has been well recognized. Clays can also be used to adsorb arsenic, and iron, aluminum, and manganese salts are often used in the removal of arsenic from water. The extent of is strongly related to arsenic speciation, arsenic concentration, pH, and the concentration of opposing anions.
Bibliography
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