Are interventions to reduce the impact of arsenic contamination of groundwater on human health in developing countries effective?: a systematic review protocol

This protocol details our proposed methods for conducting a systematic review to identify, appraise, and synthesise evidence to answer the following policy-relevant questions: a) In developing countries, are interventions to reduce the impact of arsenic contamination of groundwater on human health effective?, and b) What factors enable or constrain the effectiveness of these interventions in developing countries?Chronic arsenic pollution is now recognised as a worldwide problem, with 21 countries experiencing arsenic groundwater contamination. The largest population currently at risk is in Bangladesh, followed by West Bengal in India where groundwater concentrations frequently exceed the WHO guidelines (0.01 mgL-1) more than 10 fold [1,2].Within developing countries, groundwater is generally the preferred drinking source since it provides an alternative to polluted surface water and thereby reduces the incidence of water-borne diseases. However, the presence of unacceptably high levels of arsenic, which do not alter the taste, colour or odour of the water, has gone undetected for a number of years. As an element which is ubiquitous in many minerals, rocks and ores, arsenic is prone to natural weathering processes which enable its continual release into water as arsenite, As(III) and arsenate, As(V). Once in solution, both species display differences in bioavailability, reactivity and toxicity [3]. Additional inputs of arsenic from anthropogenic sources, such as mining and combustion of fossil fuels, further compound the problem.Arsenic is one of the most toxic and carcinogenic of all the natural groundwater contaminants, available for ingestion directly in drinking water. The physical consequences of long term exposure to elevated concentrations of arsenic are severe. Conditions include skin, lung, bladder and kidney cancer as well as pigmentation changes, skin thickening (hyperkeratosis) neurological and circulatory disorders, muscular weakness, loss of appetite an