DNA adducts in granulocytes of hospital workers exposed to ethylene oxide

Ethylene oxide (EtO), an important industrial chemical intermediate and sterilant, is classified as a human carcinogen. Occupational EtO exposure in many countries is regulated at 1 ppm (8-hr TWA), but levels of EtO-DNA adducts in humans with low occupational EtO exposures have not been reported.

We examined the formation of N7-(2'-hydroxyethyl)guanine (N7-HEG), a major DNA adduct of EtO, in 58 EtO-exposed sterilizer operators and six nonexposed workers from ten hospitals. N7-HEG was quantified in granulocyte DNA (0.1-11.5 microg) by a highly sensitive and specific gas chromatography-electron capture-mass spectrometry method. Cumulative exposure to EtO (ppm-hour) was estimated during the 4-month period before the collection of blood samples.

There was considerable inter-individual variability in the levels of N7-HEG with a range of 1.6-241.3 adducts/10(7) nucleotides. The mean levels in the nonexposed, low (< or =32 ppm-hour), and high (>32 ppm-hour) EtO-exposure groups were 3.8, 16.3, and 20.3 adducts/10(7) nucleotides, respectively, after the adjustment for cigarette smoking and other potential confounders, but the differences were not statistically significant.

This study has demonstrated for the first time, detectable levels of N7-HEG adducts in granulocytes of hospital workers with EtO exposures at levels less than the current U.S. standard of 1 ppm (8-hr TWA). A nonsignificant increase in adduct levels with increasing EtO exposure indicates that further studies of EtO-exposed workers are needed to clarify the relationship between EtO exposure and N7-HEG adduct formation.