Measurement of radon concentration in drinking water and natural radioactivity in soil and their radiological hazards

Natural radioactivity in soil, rock, building materials, and water is very important for the radiological protection point of view. Radon is one of the carcinogenic radioactive gases. Radon causes radiological risk to the public via ingestion and inhalation. The Rn-222 activity concentrations were estimated in potable water of Uttara Kannada district (Coastal region) using the Emanometry technique. Radon activity levels were found to vary from 2.37 +/- 0.19 Bql(-1) to 171.35 +/- 1.96 Bql(-1) with a mean value of 22.62 +/- 0.82 Bql(-1). The majority of the radon levels are within the reference level of 100 Bql(-1) proposed by WHO and EU Commission. Nearly 55% of the potable water had radon activity levels exceeds the MCL of 11.1 Bql(-1) proposed by USEPA. The annual average ingestion dose values are lower than the action level of 100 mu Svy(-1) as proposed by WHO and EU Commission. The activity concentration of Ra-226, Th-232, and K-40 in soil were estimated by using NaI(Tl) detector-based gamma-ray spectrometry. The average activity of Ra-226, Th-232, and K-40 in soil samples is 36.12, 50.45, and 315.35 Bq kg(-1), respectively, and the activity concentration of Ra-226 and Th-232 is slightly higher than the world average. The calculated radiological hazards are well within the world average value.