The permissible limit is 2 mgpl of uranium in drinking water sources. Nagarjunasagar has 2 mgpl of uranium. Hussainsagar, which no longer supplies drinking water, contains 20 mgpl.
The average daily intake of uranium from food or water ranges from 0.07 to 1.1 micrograms per day. But Hyderabadis who drink water from Himayatsagar take uranium 700 per cent in excess, and about 500 per cent excess in case of Osmansagar.
Medical experts said that about 99 per cent of the uranium ingested in food or water is flushed out by the body in the faeces. One per cent enters the blood but even this is removed by kidneys and excreted through the urine within a few days. A small amount of uranium will be deposited in the bones where it will remain for years. The high uranium content comes from agricultural fields where farmers use phosphate fertilisers. This category of fertilisers often contains high amounts of natural uranium.