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Gamma-ray spectrometer was employed to estimate the specific activity of the natural radionuclides in commonly used building materials of East Khasi Hills District, Meghalaya, India. The activities of 40 K, 226 Ra and 232 Th in Bq kg −1 were 40.9-777.1, 3.8-92.7 and 14.2-112.2 with their total average values of 312.4, 47.4 and 57.7, respectively. 40 K and 226 Ra concentrations were below the reported values of 500 Bq kg −1 and 50 Bq kg −1 , respectively, while 232 Th was slightly higher than 50 Bq kg −1. The average annual effective dose (outdoor) of 0.09 mSv y −1 was much lower than the recommended limit of 1 mSv y −1 for public exposure; absorbed dose rate (69.9 nGy h −1) was higher than the world average value of 59 nGy h −1. The average values of radium equivalent activity (154.0 Bq kg −1), alpha index (0.24), gamma index (0.55), external hazard index (0.42) and internal hazard index (0.54) were all less than the recommended values. Our study shows that the different types of building materials analyzed do not pose any significant radiation hazards. They are therefore safe for the construction purposes. The statistical methods applied in our study show that 40 K contributed less to the values of the radiological parameters compared to 226 Ra and 232 Th.

The study was performed using a silicon surface barrier alpha spectrometer at Bhabha Atomic Research Centre, Mumbai, India. Through the study, the observed (210)Po activity in water sample from different locations in the Domiasiat area ranges from 0.04 to 0.69 Bq/l. The daily and annual intake of (210)Po through water was also estimated and the mean value of 0.72 and 263.61 Bq, respectively, were observed. It is observed that the effective doses through water were higher than the World Health Organization recommended dose of 0.05 mSv/year. The total annual effective doses through terrestrial ingestion for all the locations was studied and the mean annual effective dose was observed to be 0.315 mSv, which, when compared to the worldwide and the Indian values, was observed to be slightly higher. The mean activity in soil is found to be 124.8 +/-5.7 Bq/kg and in meat the activity is 0.43 +/-0.05 Bq/kg. In fishes, an activity of 0.48 +/-0.07 Bq/kg in Garra lamta, 0.29 +/-0.02 Bq/kg in Neolissocheilus hexaganolepis, and 3.3 +/-0.1 Bq/kg in Macrobrachium sp. is observed. Activity concentration in plant samples was analyzed and the activity ranges from 0.020 +/-0.002 to 9.69 +/-0.35 Bq/kg. Committed effective dose by the adult population of the Domiasiat area through intake of (210)Po through these food items was also determined and compared with the Indian average value and the worldwide average value.

The study to generate the baseline of natural radiation and radioactivity in East and West Khasi Hills District of Meghalaya, India was conducted to determine the different radiation dose in selected stations. Twenty stations were selected in both the district, which include Shillong the capital of Meghalaya and the Domiasiat area, which has been identified as one with a Uranium ore deposit. The dose was measured using a Micro-R-Survey meter and from the measurement it was found out that the absorbed dose in both the districts ranges from 0.04 to 1.66 microGy h(-1). The maximum dose was observed in Kylleng (0.72 microGy h(-1)) and the minimum in Mawphlang (0.06 microGy h(-1)). Average absorbed dose and equivalent dose were found to be higher than the Indian and world average values by several orders. The radiation levels distribution was found to be non-uniform through out the selected study area.