Determination of Water Quality Index of Drinking Water Sources and Health Risk Assessment of Arsenic-Contaminated Rural Areas in Basirhat-1 Block of West Bengal

Abstract

Arsenic (As) contamination in groundwater is a major environmental problem in West Bengal. People in rural West Bengal are mostly dependent on community deep tube wells for drinking purpose. North 24 Praganas in West Bengal is one of the most Arsenic affected districts in India. Most of the deep tube wells currently being used in North 24 Praganas have already been declared to be contaminated with Arsenic. Time to time evaluation of suitability of these water sources for drinking purposes and the assessment of health risk are very essential for knowing the severity of the condition and accordingly take timely mitigation measures. In this paper, the Water Quality Index(WQI) has been determined and Health Risk Assessment has been done for drinking water sources currently in use in one of the chronically Arsenic affected Basirhat-1 block of North 24 Praganas. For calculating WQI, the weighted arithmetic water quality index method has been adopted by taking pH, TDS, Sulphates, DO(Dissolved Oxygen), total Alkalinity, Total hardness, EC, Chloride and total Arsenic as parameters. The Health Risk Assessment has been done by considering the total Arsenic found in the water samples. For Health Risk Assessment, cancer and non-cancer risk assessment were done by following the deterministic method of risk assessment recommended by US EPA (Environmental Protection Agency). The WQI results indicates that all the sampled deep tube wells of the studied area are highly unsuitable for drinking purpose. Arsenic content was found to be 4 to 24 times higher than the permissible limit. The Hazard Quotient of the sampled studied sources was calculated to be in the range of 2 to 9 which signifies the vulnerable health risk due to non-carcinogenic effect due to Arsenic. The cancer risk assessment gives a further alarming picture of the area with 1-4 persons for every 1000 population in Basirhat-1 block are prone to Cancer risk due to Arsenic. The study recommends immediate measures in the area to make all the current drinking water sources Arsenic free.