The daily intake of long-lived alpha-emitting members of the U, Th and Ac series by New York City residents has been estimated from measurements of diet, water and air samples. The total daily intakes from inhalation, food and water consumption in mBq are 18 (234U), 0.7 (235U), 16 (238U), 6 (230Th), 4 (232Th) and 52 (226Ra). From this, we infer that the total daily intakes of 228Th and 228Ra are 4 and 35 mBq, respectively.

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Measurement of 226Ra and calcium in 588 samples of human vertebrae from 13 countries are combined with those of other investigators to describe the average global Ra concentration in human bone. The median population-weighted concentration is 23 fCi 226Ra/g of calcium. The median concentration calculated here delivers an a dose of 0.4 mrad/yr to cells lining bone surfaces that are thought to be critical in the production of osteosarcoma. 226