"We are thinking, how we can reduce the price of Sono filter so that poor affected people can get the benefit", said Dr. Munir at Kushtia on Friday. Dr. Munir, along with Bangladesh scientist Dr. Abul Hussam working in US, innovated the filter. Dr. Hussam is a Chemistry professor at George Mason University in Virginia.

This correspondent also talked to Hussam over telephone.

"More than sixty per cent of the total population of Bangladesh are at the risk of being affected by arsenic", Dr. Munir said.

He recently returned home from USA where he received the prestigious million dollar Grainger Challenge Prize awarded by the National Academy of Engineering (NAE) for innovating the easy technology to remove arsenic from groundwater.

According to Munir, Sono filter was one of the 15 technologies (Grainger Challenge Finalist) out of more than 100 entries selected to compete in the final test, held last year.

The technology test and evaluation was done by the United States Environmental Protection Agencies (US-EPA) at Cincinnati, Ohio and reviewed by a 10-member committee, the two scientists said.

NEA President A Wulf declared the prize in Washington on February 1 this year and the price giving ceremony was held on February 20 at NAE Complex in Washington.

Sono is a simple and cheap filter made with easily available materials.

Its use has stopped spread of arsenicosis in about 1000 villages across the country. No arsenicosis patient was detected in the villages in last two years after people began using it, according to the innovators.

It costs between Tk 1600 and Tk 2500 and the user does not have to use any ingredient or chemical to purify water.

The filter has been approved by the World Health Organisation (WHO), Bangladesh government and the local bureau of Isotope Hydrology Section of the International Atomic Energy Agency (IAEA).

"We feel, our responsibilities have increased and we are aware of it," said Dr. Abul Hussam on telephone.

The innovators said the prize money would be used for further research on arsenic-contaminated water.

A research centre named Abul Foundation has been set up in George Mason University for more research on the subject, he said.