Estimation of the cancer risk of genotoxic chemicals by the rad-equivalence approach.

The genotoxic effectiveness of ethylene oxide is compared with that of gamma-radiation, as measured by induced transformation of C3H 10T1/2 mouse embryo fibroblasts. The resultant value of the quality factor, Q approximately 80 rad/mM X h, is compatible with earlier data on mutation and other endpoints in various test systems. This quality factor can thus be used to estimate the risk of exposures to ethylene oxide or its precursor, ethene, on the basis of human doses monitored by haemoglobin adducts.