A study on thorium levels in human femur bones

The incorporation of naturally occurring thorium isotopes in human femur bones was studied by analyzing 28 bone samples. The results show that the activity concentrations of 232Th and 230Th are in the range of the blank values resulting in an upper limit of theirs activity concentrations in human bones. The presence of 228Th can be attributed, on the basis of model calculations, to the radioactive decay of deposited 228Ra. We conclude that thorium is not detectably incorporated into human bones