Field testing of over 30,000 wells for arsenic across 400 villages of the Punjab plains of Pakistan and India: Implications for prioritizing mitigation

Abstract

Most of the rural population of 90 million in Punjab province in Pakistan and Punjab state in India drinks, and cooks with, untreated water drawn from shallow wells. Limited laboratory testing has shown that groundwater in the region can contain toxic levels of arsenic. To refine this assessment, a total of 30,567 wells from 383 villages were tested with a field kit in northern Punjab province of Pakistan and western Punjab state of India. A subset of 431 samples also tested in the laboratory show that 85% of wells were correctly classified by the kit relative to the World Health Organization guideline of 10 µg/L for arsenic in drinking water. The kit data show that 23% of the tested wells did not meet the WHO guideline for arsenic but also that 87% of households with a well high in arsenic live within 100 m of a well that meets the WHO guideline. The implication is that many households could rapidly lower their exposure if the subset of safe wells could be shared. In a follow-up conducted one year later in five villages where 59% of wells were elevated in arsenic, two-thirds of households indicated that they had switched to a neighboring well in response to the testing. The blanket testing of millions of wells for arsenic in the region should therefore be prioritized over much costlier water treatment and piped water supply projects that will take much longer to have a comparable impact.

Chemical Contamination of Drinking Water in Resource-Constrained Settings: Global Prevalence and Piloted Mitigation Strategies

“…Globally, most of the burden of chemical contamination falls on LMICs, with some significant contamination in the United States. Within LMICs, many of the people exposed (particularly in sub-Saharan Africa and Asia) live in rural areas, with little water infrastructure and limited financial resources (8,81,82). Within the United States, Pb, NO − 3 , and As affect both urban and rural populations, with the impact felt disproportionately by persons who are socioeconomically disadvantaged and marginalized (5,10,83).…”

“…In Bangladesh, where a significant fraction of the rural population is exposed to As in groundwater, alternative groundwater sources have had the greatest impact on reducing exposure to date (81). This is largely due to the widespread testing and marking of hand-pumped shallow tubewells (STWs), which have enabled households to switch to nearby low-As STWs (81) or a nearby community deep tubewells (DTW).…”

“…Jamil et al (176) recently estimated that the cost per reduced As exposure as a result of well testing that resulted in well-switching to an STW was nearly 10 times lower than the cost of installing a DTW or a piped water supply. Surveys in India have suggested that well-switching could be an effective mitigation strategy for F and NO − 3 contamination there as well (81). With well-switching, the time spent collecting water tends to increase significantly; in one study in Bangladesh, water collection time increased 15-fold (177).…”

Socioeconomic and recharge effect on spatial changes in the groundwater chemistry of Punjab, Pakistan: a multivariate statistical approach

“…Arsenic and fluoride are contributed by pesticide, fertilizers, hydrofluorocarbon, and water abstraction [18,21]. Hydroxyapatite mineral releases As in high-alkaline water, while F − is enriched in alkaline environment, minerals weathering, fluorite dissolution, dolomite dissolution, and arid conditions [11,13]. Urea fertilizer contributes to NO 3 − and NO 2 − pollution in addition to animal waste [28].…”

“…A survey of 383 villages of Punjab showed 23% samples have As greater than 10 µg/L, while 11% exceed 50 µg/L. Most of these villages lie across River Ravi which has been dried up after promulgation of Indus water treaty [13]. Maximum value of As and F − in east and south Punjab districts was 906-1000 µg/L and 2.8-8.6 mg/L, respectively [14,15].…”