Natural radioactivity as an impact factor in drinking water quality

This study has evaluated the levels of natural radionuclides in spring water and drilled water, which are used as potable water reservoirs and samples from the local water supply network, in the island Ikaria in the Aegean Sea and potable spring water in Loutraki in the Korinthiakos Gulf, Greece. The activity concentrations of Ra-226 and Rn-222 were in the range of <0.1-0.7 Bq l(-1) and <0.1-114 Bq l(-1), respectively. The radiological impact on the habitants, due to consumption of drinking water, was calculated taking into account the annual intake, through ingestion, of Ra-226 and Rn-222. In order to estimate the radiological impact from Rn-222 inhalation, due to its release from water, the mean contribution of the waterborne Rn-222 to the indoor air concentrations was evaluated on the basis of the transfter coefficient of 10(-4) from water to air. the effective dose equivalents due to Ra-226 ingestion were in the range of 15-175 mu Sv y(-1), with the maxima reaching the recommended limit of 100 mu Sv y(-1). The effective dose equivalents due to Rn-222 ingestion were in the range of 0.1-114 mu Sv y(-1). For both radionuclides, the highest doses were corresponding to the ingestion of potable spring water, compared to the drilled and tap water. The resulting effective dose equivalent from the ihalation of the waterborne Rn-222, in equilibrium with its daughters, was in the range of 0.36-85 mu Sv y(-1). According to our results, the ingestion of Ra-226 presents the higher impact factor of natural radioactivity in drinking water of the studied areas and appropriated remedies should be taken.