Bangladesh's arsenic water concern

That is the finding of a new study, carried out by a Calcutta university, which has criticised the performance of some arsenic test kits used in the country.

"The testing kits are not capable of measuring the water sensitively," Dipankar Chakraborti told the BBC World Service's Science In Action programme.

"The problem is unreliability; you just don't know. The tests are like a child sometimes - it might be in a good mood, sometimes in a bad mood."

Testing

Over a decade ago, scientists in Bangladesh discovered that drinking water drawn from wells was contaminated with arsenic.

To avoid people drinking polluted water, portable water testing kits were introduced, designed to monitor the countries 1.3 million wells.

However, according to Dipankar Chakraborti, head of environmental studies at Jadavpur University in Calcutta, said some of the test kits being used are nowhere near sensitive enough to give a reliable answer.

Since 1996, he has tested 2,866 water samples from wells that were previously labelled as being safe by field workers.

"In some case we have found more than 50% arsenic, in some cases 80% and in others less than 20%, but the thing is that you don't know what will be the result."

Arsenic contamination is a major problem in the region where large water well sinking programmes have been carried out for the last 20 to 30 years.

A well-meaning attempt to provide cleaner drinking water means that whilst deep wells avoid surface contamination from harmful bacteria, these deep wells tap ground water that has come from the Himalayas and which is often naturally contaminated with dangerous levels of arsenic.

Disease

As a result, contaminated drinking water affects around 20 million people in Bangladesh and the neighbouring Indian state of West Bengal.

More than 10,000 people are known to have arsenic-related diseases, but it is thought that many more cases go unreported.

Explaining the long-term health risks associated with high concentrations of arsenic, Dr Chakraborti warned: "If you drink for a prolonged time 50 microgrammes per litre of arsenic-contaminated water - out of 100 people, 1.2 people could get cancer."

The Bangladeshi Government sets the water safety level at 50 parts per million, despite the World Health Organization's recommendation that contamination levels should not exceed 10 parts per million.

Dr Chakraborti asserted his dissatisfaction with the government's recommendations when he said: "All over the world, the recommended level is 10.

"In this developing country, the amount of arsenic is 50 and that is really unbelievable to a scientist."