Sister-chromatid exchange induction in peripheral blood lymphocytes of rats exposed to ethylene oxide by inhalation.

Male Fischer-344 rats were exposed to target concentrations of 0, 50, 150 or 450 ppm ethylene oxide (EO) for 6 h/day for 1 or 3 days. Blood was removed by cardiac puncture and cultured in the presence of 5-bromodeoxyuridine for sister-chromatid exchange (SCE) and chromosome-breakage analyses. EO caused a concentration-dependent increase in SCE following both 1 and 3 days of exposure, and the effects appeared to be additive. No significant dose-dependent increase in chromosome breakage was observed, and reasons for this apparent discrepancy with other published data are discussed. These findings are consistent with the occurrence of elevated SCE frequencies in occupationally-exposed workers, and the results demonstrate for the first time that SCE can be detected in cultured lymphocytes of rodents following inhalation exposures.