ARSENIC

Natural contamination of ground water by arsenic has become a crucial water quality problem in West Bengal, where millions of people in 68 blocks of eight districts are affected. The presence of arsenic in natural water is related to the process of leaching from the arsenic containing source rocks and sediments. It is generally associated with the geochemical environments such as basin fill deposits, inputs from geothermal sources, mining wastes and landfills. Inorganic arsenic generally, exists in two predominant states, arsenite (NaAsO₂) and arsenate (Na₂HAsO₄), both of which are toxic to man and plants. It is well known that consumption of arsenic contaminated groundwater leads to chronic health effects. Signs of chronic arsenicalism include dermal lesions, peripheral neuropathy and skin cancer. These clinical symptoms, especially dermal lesions (the most commonly observed symptom) generally occur after some years of consumption of arsenic contaminated drinking water.