Determination of radon activity concentration in drinking water and evaluation of the annual effective dose in Hassan district, Karnataka state, India

The radon concentration has been determined in 27 drinking water samples of Hassan district and was estimated by using emanometry technique and physicochemical parameters were estimated using standard techniques. The Rn-222 concentrations in water are varying from 0.85 +/- A 0.2 to 60.74 +/- A 2.5 Bq l(-1) with an average value of 26.5 +/- A 1.65 Bq l(-1). This study reveals that 66 % of the drinking water samples have radon concentration level in excess of the EPA recommended maximum contamination level of 11.1 Bq l(-1). There is no significant correlation noted between radon concentration and physicochemical parameters. The mean annual effective ingestion doses received from all samples are lower than 0.1 mSv y(-1).