Are the risks from tritium exposures being underestimated?

Tritium is a radionuclide that will be used and produced in fusion reactors. Tritium toxicity is well known, but its health consequences are more difficult to assess, due to difficulties in assessing doses and to the very few cases of contamination that have occurred since it started being used. The assessment of risks resulting from tritium exposure is based on ICRP models that enable the calculation of doses in tissues, by means of a weighting factor WR, based on the relative biological effectiveness of the various radioactive emissions. Some authors are currently asking for a revision of the weighting factor used for tritium beta-ray emissions, arguing that tritium could be incorporated into DNA. A review of the extensive research conducted on this subject shows that the relative biological effectiveness of tritium is not so different from that of gamma emissions, which are taken as reference radiations. This supports the drive to keep the current weighting factor of 1 for tritium beta emissions, initially proposed and then reaffirmed by the ICRP.