Context: Natural radionuclides are wide spread in air, water, soil, plants and in consequence in the human diet. 222 Ra is the daughter product of 226 Ra which belongs to 238 U radioactive series. Aims: Radon enters the human body through ingestion of water and inhalation. Since alpha emitters are the most dangerous, studies on water containing dissolved radon are very important. Materials and Methods: The activity concentration of 222 Ra has been analyzed in water samples collected from lakes, open wells, drilled wells, taps and rivers in and around Mysore city, Karnataka State, India using radon emanometric technique. Results: The present study shows a wide range of radon concentration in water, which varies from below detection limit to 643.9 BqL -1 with a median of 15.8 BqL -1. An annual effective dose with a median of 0.043 μSv y-1 was estimated from the ingestion of 222 Ra through water. Conclusions: 222 Rn concentration in 80% of bore-well water samples are higher than the maximum acceptable contaminant level of 11.1 BqL -1 as prescribed by the environmental protection agency.
The 222 Rn concentrations in 80% of the bore well water samples are higher than the 11.1 BqL -1 prescribed by the EPA. But radon concentration is found to be less in surface water and tap water. Radon concentration in 40% of the bore well water samples are in the range of 4-40 BqL -1 . Consequently, the ingestion dose to the children, adult and the effective dose was found to be with a mean of 0.026, 0.01 and 0.162 μSvy-1 respectively, which is less than the 100 μSvy-1 as recommended by WHO..