Research Scholar National Institute of Pharmaceutical Education and Research Guwahati Guwahati, India
Background: Heavy metals such as arsenic (As) in water resources are a growing global health concern. Despite studies reporting environmental contamination and potential health hazards posed by As in drinking water in India, the exact health risk remains a matter of ongoing debate.
Objectives: To assess the human health risks associated with contamination of As in drinking water in India.
Methods: A systematic literature search to identify epidemiological studies was performed in PubMed, Scopus, and Google Scholar from inception to January 1, 2023. A combination of keywords, MeSH terms, and entry terms on drinking water, As, and India was used in combination with Boolean operators. The U.S. Environmental Protection Agency (USEPA) model was used to assess cancer and non-cancer risks in adults and children. The Incremental Lifetime Cancer Risk (CR) and Hazard Quotient (HQ) were used to determine cancerous and non-cancerous risk levels in exposed populations. The cancer slope factor (1.5 mg/kg-bw/day) and oral reference dose (0.003 mg/kg) of As were adopted from US EPA (2005) screening levels. Meta-analysis was performed using a Z-score approach to estimate differences in effect size.
Results: We found a total of 960 studies through a database search, of which 16 studies with 1,349 samples from eight states in India were included. In all those regions, the cancerous risk through exposure to As contaminated drinking water was higher (CR:1.69x10¬-6 to 0.11) than the safety level of USEPA. The non-cancerous risk assessment showed that six states had HQ values above 1 (HQ=1.13 to 247.49), suggesting health effects in children and adults. Compared to other states, the cancerous and non-cancerous risks in states near the Indo Brahmaputra Gangetic plane were higher in the order of West Bengal (CR=0.01, HQ=22.81), Bihar (CR=0.002, HQ=5.87), Uttar Pradesh (CR=0.001, HQ=4.2) and Assam (CR=0.001, HQ=4.1). Meta-analysis of the data indicates that the average effect size using Z-score was -0.0056 (95% CI: -0.34, 0.33).
Conclusions: Our findings suggested that the As-contaminated drinking water in India, especially the states of Indo Brahmaputra Gangetic plane, poses significant cancer and non-cancer risks, making the population susceptible to health hazards in the future. We recommend health authorities to conduct constant monitoring of As contaminations and implement purification improvement programs to manage the health risk.
