# Radon Levels of Water Sources in the Southwest Coastal Region of Peninsular Malaysia
###### Abstract  
Across populations, the dominating source of public exposure to radiation is radon gas. In the present study, we aimed at determining the concentration of radon in water sources from the southwest coastal region of Peninsular Malaysia. A total of 27 water samples were taken from various water sources which included groundwater, as well as hot spring, lake, river, seawater, and tap water; the radon concentrations were measured using a RAD7 portable radon detector. The radon concentrations ranged from 0.07 \(\pm\) 0.12 to 187 \(\pm\) 12 Bq 1\({}^{-1}\), with an average of 21 \(\pm\) 12 Bq 1\({}^{-1}\). The highest concentration was found in spot spring water, with an average concentration of 99 \(\pm\) 6 Bq 1\({}^{-1}\), while the lowest concentration was found in tap water, with an average concentration of 1.95 \(\pm\) 0.61 Bq 1\({}^{-1}\). The average concentrations of radon for all categories of sampled water were below the 100 Bq 1\({}^{-1}\) WHO guidance level for safe drinking water. According to the ICRP effective dose conversion factor and UNSCEAR (2000), the total effective dose from the summation of inhaled and imbibed water was calculated from the aqueous radon concentrations, with an average effective dose of 4.45 \(\upmu\)Sv y\({}^{-1}\), well within the WHO safe drinking water guideline value of 100 \(\upmu\)Sv per year. The results of this study could support the efforts of authorities and regulators who are responsible for controlling and strategizing to ensure public safety against radon exposures. radon; RAD7; radon concentration; effective dose; ingestion; inhalation +
Footnote †: journal: Medical  
such as showering, washing clothes, and flushing toilets, radon is released from the water and mixed with indoor air. Accordingly, radon from water contributes to the total risk associated with radon in indoor air, and its radioactive decay products are exposed to sensitive cells in the stomach, and other organs, once absorbed into the bloodstream [3]. Generally, when radon decays post inhalation and ingestion, the released energy is at levels capable of creating damage in various living tissues, for example, the formation of free radicals that can lead to unnatural reproduction of cells and consequent risks of malignant disease. A study has claimed that radon inhalation dissolved in and released from water intended for human consumption accounts for 89% of an individual's estimated cancer risk [4]. Accordingly, radon measurement plays a vital role in community health assessment, and awareness of radon levels in household water supplies is critical for protecting humans against the effects of exposure. Radon gas and progeny concentration surveys are of global interest, undoubtedly connected with the formal recognition, in 1988, by the World Health Organization (WHO) that, in many countries, radon was the second leading cause of lung cancer after tobacco smoke [5]. For this reason, radon has been classified as a group 1 carcinogen by the International Agency for Research on Cancer (IARC), a branch of the WHO [6; 7]. For present interests, elevated concentrations of radon in drinking water have been linked with radiation doses of concern to the stomach lining [8], with a potential significant risk for stomach and gastrointestinal cancer [9]. Various radon levels have been introduced to protect human health from exposure to radon from drinking water consumption. For example, the U.S. Environmental Protection Agency (USEPA) has set a reference level of maximum contaminant level (MCL) for radon in drinking water of 300 pCi 1\({}^{-1}\) or 11.1 Bq 1\({}^{-1}\)[10]. Similarly, Euroatom has recommended a reference limit for radon concentration in drinking water of 11 Bq 1\({}^{-1}\)[11]. Conversely, in 2004, in the third edition of the WHO Guidelines for Drinking-Water Quality, the WHO's guideline for radon concentration level is 100 Bq 1\({}^{-1}\)[12]. The WHO recommendation links to a committed effective dose equal to 100 uSv y\({}^{-1}\) for consumption of drinking water [12; 13].