Age-dependent annual effective dose estimations of 226 Ra, 232 Th, 40 K and 222 Rn from drinking water in Baling, Malaysia Nisar Ahmad, Jalil ur Rehman, Muhammad Rafique and Tabassum Nasir ABSTRACT 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 226 Ra, 232 Th, 40 K and 222 Rn were 44.2 ± 3.9, 38.1 ± 5.0, 140.9 ± 10.6 mBq l À1 and 5.7 ± 0.68 Bq l À1 , respectively. Cumulative annual effective doses due to ingestion of 226 Ra, 232 Th, 40 K and 222 Rn for infants, children and adults were estimated to be 13.77, 2.857 and 2.581 μSv y À1 , 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 μSv y À1 , respectively. A positive correlation (R 2 ¼ 0.87) was observed between 222 Rn and 226 Ra determined by RAD-7 and HPGe detectors, respectively. In this study, the estimated annual effective doses due to ingestion of 226 Ra, 232 Th, 40 K and 222 Rn for infants, children and adults were found to be below the World Health Organization (WHO) recommended limits of 0.1 mSv y À1 . Nisar Ahmad (corresponding author) Jalil ur Rehman Department of Physics, Baluchistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan E-mail: ahmadnisar31@gmail.com Muhammad Rafique Department of Physics, The University of Azad Jammu and Kashmir, Muzaffarabad, Azad Kashmir 13100, Pakistan Tabassum Nasir Department of Physics, Gomal University, Dera Ismail Khan, Pakistan Key words | effective doses, HPGe, RAD-7, radionuclides, radon, water INTRODUCTION Measurement of naturally occurring radioactive materials in drinking water is an important subject for public health studies, which permits the estimation of public exposure to radiation by using drinking water (Salih et al. ). Drinking water contaminated with natural radionuclides is one of the main causes of the health hazard to the population due to internal exposure of the absorbed radionuclide’s decay inside the human body. Inhalation or ingestion of small amounts of radionuclides can become a serious health risk. It is estimated in an UNSCEAR report that due to ingestion of 226 Ra, 232 Th, and 40 K, an average effective dose of 0.29 mSv y À1 is received worldwide (UNSCEAR b). Pol- luted drinking water is one of the sources of many diseases in developed and developing countries of the world. The deter- mination of natural radioactivity in drinking water is very helpful to estimate the public exposure to ionizing radiation due to ingestion of residential water consumption because the doses from these pathways are strongly connected to the amount of existing radionuclides. Radionuclides 226 Ra, 222 Rn, 234 U from the decay series of 238 U, 228 Ra, and 232 Th are most commonly found in water. Like other radionuclides, 222 Rn is most toxic and hazardous due to its solubility in water and can easily pass through underground water sources. Radon enters into the human body through ingestion from drinking water and inhalation from the air. Ionizing beta and gamma radiations emitted by radon and its progenies may cause cancers in human organs (USEPA ; Lee & Kim ). It is reported by USEPA () that lung cancer due to inhalation of radon released from consump- tion of water in dwellings and stomach cancer from ingestion of radon in dwellings are the primary health 32 © IWA Publishing 2018 Water Science & Technology: Water Supply | 18.1 | 2018 doi: 10.2166/ws.2017.094 Downloaded from https://iwaponline.com/ws/article-pdf/18/1/32/205582/ws018010032.pdf by guest on 22 May 2020