Risk assessment due to ingestion of natural radionuclides and heavy metals in the milk samples: a case study from a proposed uranium mining area, Jharkhand.

Ingestion of radionuclides and heavy metals through drinking water and food intake represents one of the important pathways for long-term health considerations. Milk and milk products are main constituents of the daily diet. Radionuclides and heavy metals can be apprehended in the ecosystem of the East Singhbhum region which is known for its viable grades of uranium, copper and other minerals. For the risk assessment studies, samples of milk were collected from twelve villages around Bagjata mining area and analysed for U(nat), 226Ra, 230Th, 210Po, Fe, Mn, Zn, Pb, Cu and Ni. Analysis of the results of the study reveals that the geometric mean of U(nat), 226Ra, 230Th and 210Po was 0.021, 0.24, 0.23 and 1.08 Bq l(-1), respectively. The ingestion dose was calculated to be 12.34 μSvY(-1) which is reflecting the natural background dose via the route of ingestion, and much below the 1 mSv limit set in the new ICRP recommendations. The excess lifetime cancer risk was estimated to be 1.72×10(-4) which is within the acceptable excess individual lifetime cancer risk value of 1×10(-4). The geometric mean of Fe, Mn, Zn, Cu and Ni was 4.91, 0.29, 4.77, 0.56 and 0.48 mgl(-1), respectively; whereas the daily intake was computed to be 0.44, 0.03, 0.43, 0.05 and 0.04 mg/day, respectively. Pb was not detected in any of the samples. The hazard quotient revealed that the intake of the heavy metals through the ingestion of milk does not pose any apparent threat to the local people as none of the HQ of the heavy metals exceeds the limit of 1.