Mutagenicity of alpha-particles from plutonium-238 in human fibroblasts

We have measured cell inactivation and mutation induction at the HGPRT locus in cultured normal embryonic skin fibroblasts exposed to alpha-particles from plutonium-238 (LET 100 keV/μm) and 250 kVp x rays. The survival curves for alpha-particles are exponential characteristic of high-LET radiation. The mean lethal dose, D0, is approximately 120 rads for x ray and 23 rads for alpha-particles. The data indicate that at a given survival level, the mutation rate is greater for alpha-particles than for x-ray. In order to determine the repair capacity in human fibroblasts for damage induced by x ray or alpha-particles and its relationship to cell inactivation and mutation induction, liquid-holding recovery and dose-fractionation studies were performed. The data suggest that normal human fibroblasts cannot repair sublethal, potentially lethal, and premutational damages induced by alpha-particles