nearly 50 per cent of Calcutta's population may risk developing cardio-vascular diseases due to high carbonate content in drinking water, says a study. A B Dasgupta, member of the West Bengal planning board, says that residents of Salt Lake, north and south Calcutta, have been drinking brackish water containing such carbonates daily for the last 20 years. This might result in heart ailments and artery blockage.

A study conducted by the Central Groundwater Board, shows that chloride and special conductance of the groundwater in northern and eastern part are 500 mg per ml and 2,000 microsiemens per cm respectively at 25