Determination of U in Japanese human tissues by the fission track method

Uranium in several human tissues (lung, liver, kidney, muscle, spleen, heart, cerebrum and bones) from Japanese in the Tokyo area was determined by the fission track method. The average U content was the highest in lung with 1.70 ppb wet, and decreased in the order of lung greater than bones greater than heart and muscle greater than kidney greater than liver and spleen, showing markedly different tendencies from the description in the 1982 UNSCEAR Report (UNSCEAR82). Correlations were observed between U content in lung and in other tissues. These data suggest that the contribution of inhalation of U to its total intake is not negligible. The total body burden of U for the ICRP Reference Man (ICRP74) was estimated to be about 40 micrograms, which is rather small compared with the average normal burden of 90 micrograms currently accepted by the International Commission on Radiological Protection (ICRP79).