Tuesday, September 4, 2007

Arsenic in drinking water

Scientists believe that about 140 million people, especially in developing countries, are being continuously poisoned by arsenic in their drinking water. Arsenic is very poisonous metalloid that is often used in pesticides, herbicides and insecticides. The arsenic in the groundwater is of natural origin and being released from the sediment into the groundwater due to the anoxic conditions of the subsurface. This concerning number of 140 million people will lead to higher cancer rates in the future. But not only water is poisoned by arsenic because even rice that is grown on these areas has health risk and this is very big problem for more than 70 countries, especially in South and East Asia. Since rice is usually grown in paddy fields, often flooded with water from the same arsenic contaminated wells and in many Asian countries rice is the essential food. Massive epidemic of arsenic poisoning has already taken place in Bangladesh and its neighboring countries.

Drinking water with high concentration of arsenic can lead to high rates of developing some type of cancers, including tumors of the lung, bladder and skin. Many people still don't know how dangerous this drinking water could be because some of the effects happen many years after the first exposure to arsenic. To make things look even worse scientist predict that in the long term one in every 10 people that consumed water with high concentration of arsenic will die from it and this is sadly the highest known increase in mortality from any environmental exposure. Despite the fact that this has become major problem, governments still failed to give proper significance and the priority that this problem, especially considering numbers of possible victims, deserves. It looks like those reports of poisonous communities in Bangladesh from 80s are being easily forgotten.

This picture shows countries in Asia affected with groundwater arsenic contamination and is clearly visible that arsenic contamination is becoming problem in many of Asian countries. Five major incidents caused by groundwater arsenic contamination were in Bangladesh, West Bengal-India, Inner Mongolia, Xin-Xiang Provinces in China and Taiwan.

But how did the large scale contamination began? It all started with originally one very good idea that went «slightly» wrong and it all started in the late years of the 20th century as aid agencies promoted a massive tube well drinking-water program. This program was designed to prevent drinking surface waters which can be contaminated with bacteria that can cause diarrhea and other diseases, but unfortunately failed to test for arsenic in the groundwater not suspecting that well water would emerge with elevated levels of arsenic because arsenic is naturally present in soil and it leaches into groundwater. Since than many Asian countries like China, Cambodia and Vietnam and some other countries from South America were exposed to contamination. North America and Europe aren't having major problems with arsenic because most of their water is provided by utilities, but still all wells should be regularly tested in order to avoid contamination.

The Cambridge team of scientists even developed computer models that aim to predict which regions have the highest risk for arsenic contamination after taking into account factors like geology and climate. Let us just hope that these computer models will find practical use and that governments will be more concerned to this rising problem because arsenic is very poisonous material that could mean loss of millions of lives worldwide.

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