Radiotoxicity of tritiated water and tritiated hydrogen.

Tritium in the form of tritiated water is much more radiotoxic than tritiated hydrogen. The effective dose which results from tritiated water as the oxidation product of Inhaled tritiated hydrogen gas makes about 55 per cent of the effective dose due to direct irradiation of the lungs by tritiated hydrogen only. The inclusion of the dose due to the production of tritiated water would tower the relative toxicity ratio as well as the value of derived air concentration for tritiated hydrogen. Therefore, to assess the health hazard from tritium exposure, for the two species the relative significance of 1:12,000 should be used, instead of the relative radiotoxicity ratio of 1:25,000 as given by the International Commission on Radiological Protection.