A Bangladeshi farmer shows the effects of arsenic poisoning

Man-made ponds may be responsible for widespread arsenic contamination of ground water affecting millions of people in Bangladesh, a new study says.

According to the journal "Nature Geoscience", the ponds have become a dumping ground for debris which releases arsenic into ground water.

Around 25m people in the country have been exposed to arsenic through water.

Experts have described the situation as the worst mass poisoning of a population in history.

Man-made ponds - often dug with the help of international aid agencies - were originally created to protect villagers from unclean water.

The arsenic enters water supplies from agricultural and industrial waste or from natural deposits in the ground.

Around two million people in Bangladesh suffer from arsenic poisoning. Chronic ingestion of small doses has been linked to cancer of the bladder, kidney, lung or skin, while large doses can kill immediately.

Arsenic contamination of ground water is a global problem and has occurred in other countries such as Argentina, Chile, China, India, Mexico, Taiwan, Thailand and the United States.

But the gravity of the contamination in Bangladesh is unprecedented. Millions of Bangladeshis knowingly poison themselves because there is often no alternative water source.

Harvard scientist and co-author of the study Rebecca Neumann said that arsenic contamination could be avoided by digging deeper drinking water wells below the ponds, AFP news reported.