Assessment of Drinking Water Heavy Metal Pollution Index and Associated Health Risk in Northeastern State of India

Abstract

Background: Human exposure to toxic metals by ingestion of contaminated drinking water is a global concern. For human life after air, second most essential requirement is of safe drinking water. Therefore, it is very imperative to assess the quality of drinking water in term of toxic contaminates to prevent human health risk. Objectives: To investigate levels of arsenic (As), iron (Fe) and fluoride (F) in drinking ground and surface water within entire Tripura state, to find out heavy metal pollution index(HPI) and assess the cancer and non-cancer health risk of exposure to these pollutants among local residents of study area. Methods: Arsenic and iron was measured by Atomic Absorption Spectrophotometer and fluoride by kit method. Water quality index was assessed by heavy metal pollution index (HPI). Human health risk due to intake of As, Fe and F via drinking water was evaluated using hazard quotients (HQ) and incremental lifetime cancer risks (ILCR) for children and adults. Results: Our results reveal in ground water As range 0.1 to 29.2µg/L, Fe 0.11 to 18.62mg/L and F 0.5 to 1.0mg/L.In surface water As range 0.4 to 5.6µg/L, Fe 0.11to 10.58mg/L and F was not detected in surface water.Approximately6% of total samples (N=974), had As concentrations >10μg/L standard value, about 42.84% had Fe>0.3mg/L standards limits, only 0.61% samples had F>1-1.5mg/L. All groundwater falls under the category of high HPI. However, for surface water, the HPI varies across medium, high, and critical categories. The non-carcinogenic health risks due to intake of iron (HQ 0.01-1.77 for children and 0.00-0.76 for adults) and fluoride (HQ 0.56-1.11 for children and 0.24-0.48 for adults) contaminated groundwater are higher among children than adults. Cancer risk resulting due to intake of As contaminated water is about 2 times higher in adults than children. Conclusion: The findings highlighted that the risks of cancer due to arsenic exposure through ingestion was found to exceed the acceptable thresholds in both children and adults. Ground water is prime sources for portable purpose in study areas. Based on occurrences, water quality index and health risk assessment, results emphasize the urgent need for focused attention and supply of safe drinking water in As and Fe affected study area to protect health of local residents.