Age-dependent annual effective dose estimations of 226Ra, 232Th, 40K and 222Rn from drinking water in Baling, Malaysia

Natural radioactivity and radon concentration were studied in drinking water samples from Baling area, Kedah, Malaysia, using HPGe and RAD-7 detectors, respectively. Average concentrations obtained for Ra-226, Th-232, K-40 and Rn-222 were 44.2 +/- 3.9, 38.1 +/- 5.0, 140.9 +/- 10.6 mBq l(-1) and 5.7 +/- 0.68 Bq l(-1), respectively. Cumulative annual effective doses due to ingestion of Ra-226, Th-232, K-40 and Rn-222 for infants, children and adults were estimated to be 13.77, 2.857 and 2.581 mu Sv y(-1), respectively. Average annual effective doses due to inhalation of radon released in the air during consumption and ingestion of drinking water were separately estimated to be 15.2 and 1.2 mu Sv y(-1), respectively. A positive correlation (R-2 = 0.87) was observed between Rn-222 and Ra-226 determined by RAD-7 and HPGe detectors, respectively. In this study, the estimated annual effective doses due to ingestion of Ra-226, Th-232, K-40 and Rn-222 for infants, children and adults were found to be below the World Health Organization (WHO) recommended limits of 0.1 mSv y(-1).