54 Skeletal effects can be expected to occur with high specific activity uranium tsotope such as 233 (half-life = 1.6 x 105 yrs; specific activity © 10 millicuries per gram) or 232U (half-life © 72 yrs; specific activity = 37.7 curtes per gran). Indeed, injection of each of these two uranium isotopes was shown to produce bone cancers in mice (Finkel, 1953). vrantum, however, showed no induction of bone tumors. Too Natural