LAUSR

Parts of the coastal tracts of southern Kerala, India are among the well-known High Background Radiation Areas (HBRA) of the world, attributed to the presence of radionuclides in the monaziterich beach sand deposits. A comparative study of the radon concentrations in groundwater in the high and normal background radiation areas in the coastal tract has been taken up using analytical data of 24 ground water samples collected from tube wells of ranging in depth from 6.0 to 300.0 m. The radon concentration in the samples ranged from 0.88 to 25.80 Bq.L −1 . The mean radon concentration in the study area, including those from the HBRA are within the maximum contamination levels of 300 pCi.L −1 (11.10 Bq.L −1 ) recommended by the United States Environmental Protection Agency except for a sample collected from Chavara. Groundwater from the high background radiation areas has significantly higher concentrations of radon ranging from 2.84 — 25.80 Bq.L −1 when compared to the normal background areas where the concentrations range from 0.86 — 7.46 Bq.L −1 . Radon concentration does not show significant correlation with depth of sampled wells. The mean annual effective doses of ingestion and inhalation from water-borne radon, though comparatively higher in HBRA, are well below the average doses reported from all natural sources.