The distribution of 210Pb in human bone and its impact on methods for the retrospective estimation of 222Rn exposure from in vivo measurements

It is possible to estimate radon exposure to man retrospectively by the in vivo measurement of the decay product 210Pb, which accumulates in the bones. For in vivo methods, knowledge of the distribution of 210Pb in the skeleton is needed to determine the optimal site for measurement, the skull or the knee. In this study the activity of 210Pb in a variety of bone samples from 3 individuals have been measured in vitro using underground γ-ray spectrometry. The individuals were unlikely to have had elevated intakes of Rn. These measurements give baseline data on the bone massic activity of 210Pb. They show that the massic activity is similar for each of these people and there are similar massic activities of 210Pb in the skull and the knee of the 2 individuals for which the skull was measured. Additionally for 2 of the individuals trabecular and cortical bone were separated and massic activities were found to be strongly correlated indicating that the 210Pb is associated with the hydroxyapatite.