Dose-rate effect of ethylene oxide inhalation exposures on unscheduled DNA synthesis in mouse spermatids

To further assess the relationship between DNA damage in mammalian germ cells and the rate at which fixed total chemical exposure is administered, a study was of the unscheduled DNA synthesis (UDS) induced in mouse spermatids by different concentrations and times of exposure of ethylene oxide (EtO) gas. Male mice were given inhalation exposures of EtO gas at dose rates of 1800 parts per million (ppm) for 1 h, 900 ppm for 2 h, or 450 ppm for 4 h. In all cases, the total EtO exposure was 1800 ppm.h. Immediately after exposure, and at time up to 24 h following exposure, groups of EtO-treated mice were given testicular injections of 3H-thymidine. Early spermatids, a DNA-repair competent stage, were used to study the effects of the different EtO exposures