West Bengal || Bangladesh
Middle Ganga Plain, Bihar ||
Contamination of groundwater by arsenic may be due to industrial discharges, mining operations, or mobilization of naturally occurring arsenic in sedimentary aquifers. Such contamination has been reported in China (Province of Taiwan), USA (Millard Country, Utah), Chile, Argentina and Japan (Tokyo).
Between 1983 and 1985, 14 villages in South Bengal were affected by chronic arsenic toxicity. A high level of arsenic was detected in the water from shallow tubewells (24-36 meters deep) used by those affected, but the cause of the contamination could not be ascertained. During the period July-September 1989, some residents of P.N. Mitra Lane, Behala. South West Calcutta, attended the S.S.K.M. Hospital and were found to have signs of chronic arsenic toxicity. This led us to study the problem from an environmental, clinical and epidemiological point of view.
Due to the discharge of industrial effluent after production of the insecticide Paris-Green [Copper acetoarsenite Cu(CH3COO)2 3Cu(AsO2)2] by a local factory at the P.N. Mitra Lane, Behala, ground water has become contaminated with arsenic. More than seven thousand people were using this arsenic contaminated tube-well water for drinking and house-hold purposes. Many people of the area were hospitalized and symptoms of arsenic toxicity were visible amongst a large number of the population. Analytical study reveals that soil around the area of effluent dumping point, which is at the middle of the locality, contains a very high concentration of arsenic and copper. For the last 20 years this factory had been producing 20 tons of Paris-Green per year and had been dumping its effluent in that area. It seems, the effluent treatment for arsenic removal was not adequate and finally arsenic percolated to the underground aquifers. Consequently, arsenic concentration in the ground water is very high. Both arsenite and arsenate are present in groundwater. An alternative source of water other than the ground water is immediately necessary for the people of P.N. Mitra Lane.Highest concentration of arsenic recorded was 8000 mg/l.
An industry was producing 20-30 tons of Paris Green [Copper acetoarsenite Cu(CH3COO)2 3Cu(AsO2)2] per year and was discharging most of the effluent without proper treatment in an open land just outside the boundary of the factory. Due to the high porosity of the soil, arsenic percolated and contaminated the underground aquifer. More than 7000 people living around the discharge point, were exposed to arsenic contaminated water. Primary investigations and follow-up studies in the area, carried out for the last 8 years, have revealed that some of the distant tubewells which were earlier free form arsenic, are getting contaminated now. In May 1997, a preliminary analysis of arsenic in the urine, hair and nails of some of the people drinking contaminated water from CMC deep tubewells indicated a higher arsenic concentration than in the normal population.