8. What has happened in areas where drinking water is heavily contaminated?
Arsenic levels in natural waters are usually low (a few µg/litre). However, there are several areas in the world where arsenic-bearing minerals are in contact with groundwater. In such areas, drinking water from underground wells can become heavily contaminated with natural inorganic arsenic, in excess of 1000 µg/litre in some cases. This has been a serious health problem in countries like West Bengal in India, Taiwan, Chile and Mexico and is now a serious problem in Bangladesh.
In Bangladesh, the water in many districts is contaminated and large populations are regularly drinking water containing more than 50 µg/litre. Long-term exposure to inorganic arsenic in drinking water can cause adverse effects on health, such as skin changes and cancer, which have been reported in these regions over the last hundred years. In Taiwan, a resulting blood vessel disease, known as blackfoot disease, resulting eventually in progressive gangrene has been studied since the 1920s. (see question 7.2). More...