Retrospective determination of U and Pu isotopes and atom ratios in lung samples from Vienna, Austria

Uranium and plutonium isotope concentrations as well as ²³⁶U/²³⁸U and ²⁴⁰Pu/²³⁹Pu atom ratios were measured by AMS in human lung samples from the early 1960s. The ²³⁶U concentrations as well as the ²³⁶U/²³⁸U atom ratios show a maximum in 1964, ²³⁹Pu and ²⁴⁰Pu concentrations are increasing continually from 1962 to 1965. ²³⁶U/²³⁸U atom ratios are lower by two orders of magnitude compared to corresponding aerosol data from Vienna, probably due to older ²³⁸U deposited in the lungs, enhanced ²³⁸U concentrations in the city air, and activity partition within different particle sizes. The ²³⁶U/²³⁹Pu atom ratios in lung samples are also lower than expected from the aerosol data, while ²⁴⁰Pu/²³⁹Pu atom ratios lie well within the range typical for nuclear bomb fallout.