SUMMARY

The current biokinetic model used by the ICRP to describe the dosimetry of carbon-14-labelled compounds is exceedingly conservative. It assumes a single compartment model with a half-life of 40 days. This model overestimates the dose coefficients for most carbon compounds up to a factor of 200. A new generic biokinetic model for carbon is being considered as an improvement upon the current model suggested by the ICRP. Many carbon-14-labelled compounds will be considered for all intake pathways: ingestion, inhalation, and injection. The benefit of this new model will be more realistic dose coefficients that could be implemented as regulatory guidelines for annual limits on intake. Many approaches for developing a new carbon model can be investigated, all of which contain physiological significance, unlike the current ICRP model. The ideal final product of this research should be a predictive biokinetic model for 14C labelled substances that improves upon the current ICRP model. If an enhanced generic radiocarbon model cannot be developed, a greater understanding of the behavior of 14C-labelled substances should result.