Groundwater arsenic contamination and its health effects in India

Groundwater is a critical resource in India for the supply of drinking water and for irrigation. Its usage is limited not only by its quantity but also by its quality. Among the most important contaminants of groundwater in India is arsenic, which naturally accumulates in some aquifers. In this study we create a random forest model with over 145,000 arsenic concentration measurements and over two dozen predictor variables of surface environmental parameters to produce hazard and exposure maps of the areas and populations potentially exposed to high arsenic concentrations (>10 µg/L) in groundwater. Statistical relationships found between the predictor variables and arsenic measurements are broadly consistent with major geochemical processes known to mobilize arsenic in aquifers. In addition to known high arsenic areas, such as along the Ganges and Brahmaputra rivers, we have identified several other areas around the country that have hitherto not been identified as potential arsenic hotspots. Based on recent reported rates of household groundwater use for rural and urban areas, we estimate that between about 18–30 million people in India are currently at risk of high exposure to arsenic through their drinking water supply. The hazard models here can be used to inform prioritization of groundwater quality testing and environmental public health tracking programs.

Section: Resultssupporting

confidence: 84%

Groundwater Arsenic Distribution in India by Machine Learning Geospatial Modeling

Podgorski

Chakravorty

et al. 2020

“…The~16% of samples here exceeding the WHO limit of 0.13 µM (10 µg.L −1 ) [4] is lower than other reports that~33% of wells in Bihar (n~20,000) exceed the same guideline [85]. In part, the higher sampling density in Patna district may contribute to this difference, although not to a major extent (see above discussion).…”

Section: Arsenic and Uranium Distribution In Biharmentioning

confidence: 69%

“…Further, wheat consumption has recently been identified as an emerging route of As exposure in Bihar [84]. Although thorough reviews of the status of As in the Gangetic Basin are published elsewhere [78,85], the estimated population at risk for As contamination in West Bengal is 26 million people, followed by Bihar (9 million), Uttar Pradesh (3 million), Assam (1.2 million), Manipur (1 million) and Jharkhand (0.4 million) [85]. Widespread in nature, U is a radionuclide which geogenically occurs in granite and other rock types.…”

mentioning

confidence: 99%

Distribution and Geochemical Controls of Arsenic and Uranium in Groundwater-Derived Drinking Water in Bihar, India

Richards

Kumar

Shankar

et al. 2020

Chronic exposure to groundwater containing elevated concentrations of geogenic contaminants such as arsenic (As) and uranium (U) can lead to detrimental health impacts. In this study, we have undertaken a groundwater survey of representative sites across all districts of the State of Bihar, in the Middle Gangetic Plain of north-eastern India. The aim is to characterize the inorganic major and trace element aqueous geochemistry in groundwater sources widely used for drinking in Bihar, with a particular focus on the spatial distribution and associated geochemical controls on groundwater As and U. Concentrations of As and U are highly heterogeneous across Bihar, exceeding (provisional) guideline values in~16% and 7% of samples (n = 273), respectively. The strongly inverse correlation between As and U is consistent with the contrasting redox controls on As and U mobility. High As is associated with Fe, Mn, lower Eh and is depth-dependent; in contrast, high U is associated with HCO 3 − , NO 3 − and higher Eh. The improved understanding of the distribution and geochemical controls on As and U in Bihar has important implications on remediation priorities and selection, and may contribute to informing further monitoring and/or representative characterization efforts in Bihar and elsewhere in India.Vaishali, noting importantly that only sources within 10 km of the Ganga River were sampled) [77]. Most recently, it has been reported that 22 districts of Bihar are currently As-impacted, although no further details such as location, non-summarized data or the functional definition of "As-impacted" are included [78]. Further, wheat consumption has recently been identified as an emerging route of As exposure in Bihar [84]. Although thorough reviews of the status of As in the Gangetic Basin are published elsewhere [78,85], the estimated population at risk for As contamination in West Bengal is 26 million people, followed by Bihar (9 million), Uttar Pradesh (3 million), Assam (1.2 million), Manipur (1 million) and Jharkhand (0.4 million) [85]. Widespread in nature, U is a radionuclide which geogenically occurs in granite and other rock types. U in groundwater can occur due to natural mobilization processes under oxic conditions, and can also be associated with anthropogenic activities such as mining, coal and fuel combustion, emissions from the nuclear industry and the use of PO 4 -based fertilizers containing U [4]. As chronic exposure to U may lead to numerous adverse health impacts including bone toxicity and impaired renal function [86,87], WHO has set a provisional guideline value of 0.13 µM (30 µg.L −1 ), noting that Germany adopted a lower threshold of 0.04 µM (10 µg.L −1 ) in 2011 [88]. Elevated concentrations of U in groundwater have been identified across the globe, including in North America (e.g., Canada [89], the United States [90,91]), Europe (e.g., Finland [87], Sweden [92], Switzerland [93], the United Kingdom [94]) and Asia (e.g., Bangladesh [95], China [96,97], Korea [98], Mongolia [99], Pakistan [43] and in the...

“…This proportion is estimated at approximately 1% in the UK [ 1 ]; from 10% to 30% in the United States [ 2 ], and over 90% in Bangladesh [ 3 , 4 ]. Groundwater (GW) is a common source for PWS, and its contamination by chemicals, of either geogenic or anthropogenic origin, can lead to preventable population exposure to health hazards [ 5 , 6 , 7 , 8 ]. In particular, inorganic arsenic is a recognised carcinogen and toxicant [ 9 , 10 , 11 ] commonly present in GW [ 12 ] and arguably the waterborne inorganic chemical with the highest global detrimental impact on public health [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Hazard Ranking Method for Populations Exposed to Arsenic in Private Water Supplies: Relation to Bedrock Geology

Crabbe

Fletcher

et al. 2017

Approximately one million people in the UK are served by private water supplies (PWS) where main municipal water supply system connection is not practical or where PWS is the preferred option. Chronic exposure to contaminants in PWS may have adverse effects on health. South West England is an area with elevated arsenic concentrations in groundwater and over 9000 domestic dwellings here are supplied by PWS. There remains uncertainty as to the extent of the population exposed to arsenic (As), and the factors predicting such exposure. We describe a hazard assessment model based on simplified geology with the potential to predict exposure to As in PWS. Households with a recorded PWS in Cornwall were recruited to take part in a water sampling programme from 2011 to 2013. Bedrock geologies were aggregated and classified into nine Simplified Bedrock Geological Categories (SBGC), plus a cross-cutting “mineralized” area. PWS were sampled by random selection within SBGCs and some 508 households volunteered for the study. Transformations of the data were explored to estimate the distribution of As concentrations for PWS by SBGC. Using the distribution per SBGC, we predict the proportion of dwellings that would be affected by high concentrations and rank the geologies according to hazard. Within most SBGCs, As concentrations were found to have log-normal distributions. Across these areas, the proportion of dwellings predicted to have drinking water over the prescribed concentration value (PCV) for As ranged from 0% to 20%. From these results, a pilot predictive model was developed calculating the proportion of PWS above the PCV for As and hazard ranking supports local decision making and prioritization. With further development and testing, this can help local authorities predict the number of dwellings that might fail the PCV for As, based on bedrock geology. The model presented here for Cornwall could be applied in areas with similar geologies. Application of the method requires independent validation and further groundwater-derived PWS sampling on other geological formations.