Arsenic Threat Looms Large in India: Well Switching Provides the Way Forward
Assistant Professor, Department of Regional Water Studies, TERI University
TERI University, New Delhi, India, Apr 20 2016 (IPS) – An Indian Govt. Parliamentary Committee on Estimates on “Occurrence of High Arsenic (As) content in Groundwater” in December, 2014 stated that more than 70 million people in 96 districts in India is under threat due to As occurrence in groundwater.
A new finding suggests that it’s not only Indo-Gangetic plain that is under serious threat of As contamination in groundwater in India. An ongoing study funded by PEER Science grant from USAID and National Academy of Sciences, USA in collaboration with Lamont Doherty Earth Observatory, Columbia University, New York and TERI University, New Delhi tested 12790 handpumps/tubewells in 180 villages in Indus Basin of Punjab, India using field test kits. Out of these 25% of wells were found to be having As and Nitrate concentrations above WHO standards, while 8% of samples were found to be high in terms of fluoride. These results were attached on the handpumps/tubewells in the form of metal placards depicting whether it’s safe or unsafe for drinking.
The groundwater contaminations with respect to geogenic contaminants specifically As is spatially heterogeneous and is confined to specific regions. Based on studies conducted elsewhere in South Asia, chronic exposure to As at levels encountered in groundwater of Punjab is likely to have markedly increased mortality due to cardiovascular disease and cancers of the liver, bladder, and lungs. It has also been linked to infant mortality and impaired intellectual and motor function in children.
Chronic excess intake of F, more than the WHO standards (1.5 mg/L), can cause severe dental and skeletal fluorosis which might lead to bilateral lameness and stiffness of gait. Excess intake of NO3 can result in blue baby syndrome which is frequently observed in Punjab.
The most effective policy intervention and mitigation to reduce the health risks of chronic As, F and NO3 exposure is to avoid the source of exposure, in this case unsafe hand pumps, and switch to either safe wells. Our ongoing work in Bihar funded by International Growth Centre and some other studies have shown that if the households are made aware of the hand pumps/tube wells testing results, along with health implications of As in drinking water, leads to a substantial portion of households to switch to a nearby low-As well, markedly reducing exposure to As. However socio-cultural barriers are found to prohibiting well sharing within the communities. This is clearly an undesirable situation that needs to be and can be remedied. The main obstacle to well-switching and exposure reduction for millions of villagers is therefore lack of information: the vast majority of wells have never been tested.
There is presently, however, no organizational structure in India to deploy field kits at scale and with the necessary level of quality control, nor is there sufficient scientific understanding of the mechanisms controlling As levels in groundwater to determine where the deployment of such kits should be prioritized.
Testing wells for As provides information that is not substitutable. Because the distribution of Asincidence in groundwater is difficult to predict, and varies greatly even over small distances, the safety of a well cannot be predicted without a test. A well that meets guidelines for As in drinking water may be found in the immediate neighbourhood of a very unsafe well. Nor is there an easy way to design wells to be both safe and affordable: within shallow ( 100 m) aquifers tapped by most private wells, there is no systematic and predictable relationship between and As and well depth. At the same time, precisely because As contamination varies greatly over small distances, well tests make available an effective way to avoid exposure, namely by switching to a nearby safe well.
If the findings compliment the ongoing finding of the Bihar study then this mechanism can be replicated in most of the South-South East Asian nations which are facing this crisis. A thorough study recently conducted in Bangladesh has shown that if the member switches to a safe well then he would increase his earning by 9% (Pitt et al., 2012). Reducing exposure could therefore also increase economic growth in India for decades to come. Our findings from a different region in India, suggests that approximately 40% of the population is willing to switch to safe wells if they are informed and educated about their well status and potential health impacts of As and F consumption through groundwater.
Considering that there are approximately one million tube wells/hand pumps in Punjab and 28 people are dependent on each of the well; (population of Punjab, 28 million) and half of them turnout to be unsafe in terms of As/F and nitrate when informed 37% of people dependent on each well switch to safe well (result from ongoing study in Bihar) will alone cause lowering of exposure to a population of 5.5 million.