A comprehensive study was conducted to understand the radon (222Rn) distribution and associated radiation doses to the public in a small tropical river basin partly set in the western slope of the Southern Western Ghats of Kerala, India. Radon, though detected in all the 71 monitored wells (0.17-68.3 Bq L-1), exceeded the maximum contamination level (MCL) of 11.1 Bq L-1 for drinking water recommended by United States Environmental Protection Agency (USEPA) in eight samples from isolated pockets of highland, midland and lowland of the Karamana River Basin (KRB) and found to be well within 100 Bq L-1, the parametric value suggested by the World Health Organization (WHO) and the European Union (EU). The age-wise total annual effective doses (AEDs) of groundwater radon activity ranged from 0.5-208.4 μSv a-1 for infants, 0.4-172.2 for children and 0.5-189.7 μSv a-1 for adults. The results reveal that effective doses due to groundwater radon pose no potential public health risk in the study region. Since there is no previous background information on radon-induced radiation dose in the KRB, this work is a newfangled attempt from a public health point of view.
Keywords: Annual effective dose; Karamana river basin; RAD7 radon detector; natural radioactivity; radio ecology; radon-222.