FISSION FRAGMENT RELATIVE BIOLOGICAL EFFECTIVENESS FOR LIVER-TUMOR INDUCTION

The risk coefficients for liver tumors as derived from 60 beagles with body burdens of Cf-249 or Cf-252 were used to determine the relative biological effectiveness of fission fragments relative to alpha partic les, For liver malignancies the relative biological effectiveness was calculated to be about 2 +/- 3. The estimate based on the combined ben ign and malignant liver tumors was about 7, with a proportionately lar ger standard deviation of about +/- 14. Although the confidence interv als were aide, it is possible that the relative biological effectivene ss of fission fragments relative to alpha particles, using liver neopl asia as the endpoint, is greater than 1.0 as compared to a value only slightly above zero when bone cancer was the lesion of interest.