Tritium-Induced Effects in Paramecium Aurelia

Abstract

Summary and Conclusions

Effects induced by metabolized radioactive hydrogen (tritium or T) and presumed to be genetic in nature have been measured in Paramecium aurelia. Organisms were allowed to divide 6 to 8 times during 2 days in culture fluid containing T in concentrations varying from 1 to 100 mc per ml. With increasing radioactivity of the medium, increasing death after autogamy was observed, but no preautogamous effects were noted. The response observed after exposure to T appears to be slightly lower than that induced by emitters of more energetic /3 particles at similar dosage levels. The conclusions are that no part of the effect can be ascribed to transmutation of T, the emitted electrons alone apparently inducing the biological changes; and that the difference in efficiency between T and Sr89′90Y90 in inducing the effects observed is consistent with the observations of others concerning the dependence of the mutation constant upon rate of energy loss by densely ionizing particles.