Gamma-ray mutagenesis measurement in mammalian cells.

Application of conventional in vitro mutagenesis testing has so far failed to result in marked reduction of the total incidence of cancer. At least part of the reason may lie in the frequent use of a cell target too small to yield adequate sensitivity, and in failure to take into account the effects of cell killing in the assessment of mutagenic action. A single theoretical analysis fits the results of experimental data on gamma-irradiation applied to single marker gene testing in bacteria and to cytogenetic analysis of irradiated mammalian cells, and permits determination of the mean mutagenic dose, DoM, without complication due to cell killing. Cytogenetic monitoring of human lymphocytes which can detect mutagenic effects of gamma-radiation down to doses of < 0.1 Gy (10 rad) will also furnish an estimate of repair effectiveness at these low levels and may well be a useful tool in a program for prevention of cancer and other genetic disease.