CHAPTER 35: The Micronucleus Assay as a Cytogenetic Biomarker of Ethylene Oxide Exposure

Ethylene oxide (EtO), a chemical widely used in the sterilisation of medical equipment, is categorized as a Group 1 carcinogen by the International Agency for Research on Cancer. In this chapter, we discuss the results from epidemiological studies that have used the micronucleus (MN) assay to determine MN formation as a result of EtO exposure and provide a mechanistic understanding from the limited number of in vitro and in vivo studies available. Most of the epidemiological studies published in the period of 1985–2000, differ significantly in terms of the exposure conditions, cell type and MN assay outcome. The in vitro and in vivo studies provide comparable results, however they do not provide any definite mechanistic explanation. The studies also reveal that MN is comparatively less sensitive than sister chromatid exchanges, as a cytogenetic marker for EtO exposure.