Assessment of contributors to radiation dose following intakes of rapidly excreted [14C]-compounds.

The International Commission on Radiological Protection default biokinetic model for the assessment of radiation dose received following intakes of unspecified [14C]-compounds (DCM) appears to overestimate the radiation doses delivered by many [14C]-compounds. The DCM does not specify the route of elimination and this review of the biokinetic data for four [14C]-compounds, [14C]sevelamer, [14C]colestipol, [14C]levetiracetam and [14C]ifetroban, that are rapidly lost from the human body via different excretory pathways, indicates that the excretory pathway is the critical determinant for both the individual tissue doses and the effective dose. If there is significant faecal excretion the DCM does not overestimate the effective dose.