Arsenic is a metalloid element, which forms a number of poisonous compounds. It is widely distributed throughout the earth’s crust, and is found in groundwater supplies in a number of countries.
Soluble inorganic arsenic is acutely toxic. Intake of inorganic arsenic over a long period can lead to chronic arsenic poisoning (arsenicosis). Effects, which can take years to develop depending on the exposure level, include skin lesions, peripheral neuropathy, diabetes, cardiovascular diseases, and cancer.
Organic arsenic compounds, which are abundant in seafood, are less harmful to health, and are rapidly eliminated by the body. Human exposure to elevated levels of inorganic arsenic occurs mainly through the consumption of groundwater containing naturally high levels of inorganic arsenic, food prepared with this water, and food crops irrigated with high arsenic water sources. In one estimate, arsenic-contaminated drinking-water in Bangladesh alone was attributed 9,100 deaths and 125,000 Disability Adjusted Life Years (DALYs) in 2001.
Reduction in human exposure to arsenic can be achieved by screening of drinking-water supplies, clearly identifying those delivering water above the WHO guideline 10 micrograms arsenic per litre or national permissible limits, together with awareness-raising campaigns. Mitigation options include use of alternative groundwater sources, use of microbiologically safe surface water (e.g. rainwater harvesting), use of arsenic removal technologies, or dilution of high content arsenic source water with lower arsenic content source water that is microbially safe.