Genotoxicity of ethylene oxide: A review of micronucleus assay results in human population.

Ethylene oxide (EtO) has been categorized as "carcinogenic to humans (Group 1)" by the IARC. While several epidemiological studies have reported carcinogenicity and EtO-Hb formation; information from cytogenetic endpoints are rather inconclusive. In the present review, we focus on the results of eleven studies which have reported the results of micronucleus assay in EtO exposed workers. We have critically reviewed these studies based on the exposure assessment, concentration and duration, and compared the sensitivity of micronucleus assay to other reported endpoints like EtO-Hb, CA, SCE. The levels of EtO and EtO-Hb adducts in all the studies were strongly correlated to the results of SCE, but not to MN. MN were only observed in a limited number of studies with high EtO exposure (2-28ppm 8h-TWA) and not below the recommended concentration of <1ppm. To further understand the effect of exposure of EtO on MN assay outcome, we propose studies with more harmonized protocol for exposure assessment and MN analysis, determination of suitable sample size and use of multiple target tissues to understand the effect of metabolite.