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 ⩽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 ⩽32 to 745 mBq kg⁻¹ and in pulses it was found to vary between ⩽32 and 294 mBq kg⁻¹. The range of ²¹⁰Po activity in different types of vegetables was found to be ⩽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 ⩽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 μSv yr⁻¹) to the public compared to foods of plant origin whose mean dose ranged 0.08–128 μSv 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.