Arsenic in the drinking water – reminiscent of the movie “Lavender and old lace”?
From the times of antiquity arsenic has been a substance recognized by toxicologists. The best known form is arsenic trioxide (usually known as “arsenic”). Large doses (i.e. about one tenth of a gram) cause acute poisoning, including diarrhoea and other gastrointestinal symptoms, but also symptoms from a number of the internal organs, because arsenic has effects on critical metabolic functions in all cells. Death usually ensues from cardiovascular failure. Arsenic has been used over the years for political murders, because it is relatively tasteless. Nowadays long-term effects are more important than acute toxicity.
The health effects of arsenic from drinking water are both very well known and widely studied, because the problem is world wide, with cancer being considered as the most critical adverse outcome. Very high concentrations in drinking water have also evoked a variety of vascular diseases even leading to gangrene of the lower extremities (so called black-foot disease). Other consequences are characteristic changes of the skin, peripheral neuropathies and liver injury. All these have been seen in high-exposure areas in Taiwan and Chile, recently also in Bangladesh after the introduction of deep tube wells.
Possible effects of low concentrations
Recent Finnish studies have suggested that there may be a slightly increased risk of bladder cancer in populations consuming water from tube wells (drilled wells) in arsenic rich areas. Blood cells demonstrate changes that may predict increased risk of cancer. The association could be detected even at arsenic concentrations lower than the present limit values of arsenic (0.01 mg/l). Therefore people living in those areas where the bedrock contains arsenic, and tube wells are used, need to be given good advice. One typical characteristic of arsenic concentrations is that they may be quite different in two wells very close to each other. Therefore individual analyses are needed to ensure that arsenic contaminated water should be avoided if at all possible.
Arsenic may be a problem, especially with deep tube wells in Europe or North America, but it is usually restricted in geographical terms. In risk areas it is advisable to analyse the arsenic concentrations. In arsenic rich areas of the world, the story is very different – there the risks are very high.
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