Workers exposed to ethylene oxide have increased incidence of sister chromatid exchange

We have determined the frequencies of sister chromatid exchange (SCE) in 41 workers engaged in the sterilization of medical equipment. Each exposed subject was paired with a control matched for age, smoking habits and sex. The frequencies of SCE were markedly higher in the exposed than the control workers. The exposed subjects were divided into two groups according to time-weighted average concentrations of ethylene oxide (EtO) in the air, that were determined at the work place of each worker during the 5 min following the sterilizer opening, during the entire sterilization cycle or during the 8-h working day. One group (19 subjects) was exposed to a range of 3.7-35.5 ppm (mean, 15.8 +/- 9.8 for a sterilization cycle) and showed a mean of 13.0 +/- 1.8 SCE compared to 10.2 +/- 1.2 in controls (variance, F = 31.2; p less than 0.001). The second group (22 subjects) was exposed to 0.3 - 2.6 ppm (mean, 1.1 +/- 1.0) and had a mean of 11.0 +/- 1.6 SCE compared to 9.8 +/- 1.4 in controls (F = 4.7; p less than 0.05). Statistical evaluation of the SCE frequencies correlates SCE induction with the level of EtO exposure and also with smoking and age. Our data show that EtO can induce human chromosomal damage at very low environmental exposure levels, lower than the present Italian official limits and lower than those found even in the most technologically advanced hospitals.