Dose estimates to the public from 210Po ingestion via dietary sources at Kalpakkam (India)

Distribution of one of the natural radionuclides 210Po activity in food of plant origin such as cereals, pulses, vegetables and food of animal origin such fish, crab, prawn, chicken, egg etc. were determined in and around Kalpakkam upto a distance of 32 km radius. The general range of 210Po activity levels in all the dietary components (excluding milk and drinking water which are reported in mBq l(-1)) ranged widely from < or = 10 to 122,641 mBq kg(-1) fresh, the minimum being in vegetables and maximum being in the edible portions (muscle) of crab samples. 210Po levels in drinking water and milk samples ranged between 0.6-2.6 and 8-12 mBq l(-1) respectively. 210Po content in cereals ranged from < or = 32 to 745 mBq kg(-1) and in pulses it was found to vary between < or =32 and 294 mBq kg(-1). The range of 210Po activity in different types of vegetables was found to be < or = 10-653 mBq kg(-1). Among the different varieties of vegetables, 210Po was significantly higher in leafy vegetables (28-653 mBq kg(-1)) as compared to rooty and other types of vegetables which ranged from < or = 10-180 mBq kg(-1). In food of animal origin, the observed minimum activity of 210Po was 8 mBq l(-1) in milk and the maximum observed was 122,641 mBq kg(-1) in the muscles of crab. It was also observed that 210Po activity was found to be in higher levels in the food of aquatic animal origin (1414-122,641 mBq kg(-1)) than in the food of terrestrial animal origin (other than milk) which varied from 41 to 963 mBq kg(-1). It is evident from the present study that the foods of animal origin especially crab, fish and prawn deliver significantly greater dose (93-3364 microSv yr(-1)) to the public compared to foods of plant origin whose mean dose ranged 0.08-128 microSv yr(-1). The study showed evidence to suggest that the total ingestion dose due to 210Po received by the Kalpakkam public through dietary sources is significantly higher than the ingestion dose received due to fallout sources such as 137Cs and 90Sr.