Threat of mass arsenic poisoning in Bangladesh

Posted: 3 March 2003

A long-term epidemic of cancers and other fatal diseases is facing Bangladesh because of contamination of water supplies by naturally-occurring arsenic, according to Allan H Smith, professor of epidemiology at the University of California at Berkeley, USA, writing in the Bulletin of the World Health Organization. The catastrophe is on a vast scale and needs to be declared a public health emergency, the article warns.

Arsenic contamination of ground water has been found in many other countries, and is a global problem. But Bangladesh's plight is unprecedented, the article says - between 35 and 77 million people of the country's total population of 125 million are at risk of exposure to arsenic in their drinking water. At least 100 000 cases of debilitating skin lesions are believed to have already occurred.

"Bangladesh is grappling with the largest mass poisoning of a population in history...the scale of this environmental disaster is greater than any seen before. It is beyond the accidents at Bhopal, India, in 1984, and Chernobyl, Ukraine, in 1986," says Smith.

Based on information from recent visits to Bangladesh, Professor Smith predicts a major increase in the number of cases of diseases caused by arsenic if the population continues to drink arsenic-contaminated water. These range from skin lesions to cancers of the bladder, kidney, lung and skin, neurological effects, cardiovascular and pulmonary disease, and diabetes. The diseases may develop slowly over many years.

Studies in other countries where the population has had long-term exposure to arsenic in groundwater indicate that one in ten people who drink water containing high levels of the poison may ultimately die from cancer. Dramatic increases in such deaths and cases have been reported in Taiwan, Chile and Argentina.

The poisoning in Bangladesh stems from the creation during the last 20 years of millions of small tube-wells which are inserted into the ground at depths of usually less than 200 metres and then capped with a metal hand pump. Ironically, many of the first wells were constructed as part of a programme to provide "safe" drinking water.

The alarm was first raised when doctors saw cases of arsenic-induced skin lesions in West Bengal, India, in 1983. More than 1.5 million people were thought to be exposed to arsenic there, with more than 200 000 cases of poisoning.

Similar cases then began to appear in neighbouring Bangladesh. Arsenic contamination of water in the wells was first confirmed there in 1993 and in many studies since then. Wells in several hundred villages have been scientifically surveyed as part of a government programme, but Professor Smith says more urgent action is necessary.

"The discovery of arsenic contamination of ground-water in many nations, including Argentina, Chile, China, India, Mexico, Taiwan, Thailand, the United States and now Bangladesh, shows that this is a global problem," he writes.

Unlike other major health problems in Bangladesh, arsenic-caused diseases can be eradicated at relatively low cost, according to Professor Smith. The core activity of an emergency action plan should be rapid case ascertainment and immediate provision of arsenic-free water, followed by treating and monitoring patients, the education of communities about the risks and the provision of information about medical care.

See Arsenic on tap.