Radiation doses from some [3H]-labelled organic compounds following ingestion

Published information, especially human data, on the biokinetics of 11 compounds labelled with 3H was used to develop simple, cautious compound-specific models and to calculate both tissue absorbed doses and effective doses using the OLINDA computer code. The compounds were [3H]-cortisol, 3α-Hydroxy-5β-pregnane-11, 20-dione-7-[3H], cyclic 20 trimethylene acetal, [3H]-ifetroban, [3H]-digoxin, 7-[2'-α- methylphenyl-ethylamino[3H]]theophylline, 7-[2'-α- methylphenyl-ethylamino]theophylline-[3H], [3H]- amphetamine, [173H]-nicergoline, [3H]-colestipol, [3H]-5(S)-benzamido-4-oxo-6-phenyl-hexanoyl-l-proline and [6-3H]-thymidine. The calculated effective doses ranged from 6 to 87% of that predicted by the ICRP default model for uncharacterised organic compounds of tritium (OBTM). For all the compounds studied, the retention of 3H in the body was less than that predicted by the OBTM and the route of excretion was found to influence both tissue and effective doses. It is concluded that although the ICRP OBT model may underestimate doses for specific compounds by up to an order of magnitude, it can still be applied with caution for prospective radiological protection purposes,but it should not be applied for the interpretation of bioassay data. (authors)