What is Ethylene Oxide (EtO)?

Ethylene oxide (EtO) is a colorless, flammable gas used primarily for sterilizing medical equipment and as a chemical building block. Classified as a carcinogen by the EPA and other bodies, chronic inhalation is linked to white blood cell cancers and breast cancer. The document highlights that EtO emissions disproportionately affect low-income communities and people of color, with some areas in Louisiana experiencing cancer risks over 200 times the EPA's acceptable levels. While the EPA has updated the Miscellaneous Organic Chemical Manufacturing (MON) rule, the document argues that current regulations fail to require fenceline monitoring or a complete phaseout of the chemical, calling for stronger enforcement and the adoption of less toxic alternatives.

• Ethylene oxide (EtO) is classified as a carcinogen by the US Environmental Protection Agency (EPA), the National Toxicology Program, and the International Association of Research on Cancer. Chronic inhalation is associated with breast cancer in women and cancers of the white blood cells, including myeloma, lymphocytic leukemia, and non-Hodgkin lymphoma.
• EtO exposure disproportionately impacts low-income communities and people of color. A Union of Concerned Scientists (UCS) analysis found that over 14 million people and more than 10,000 childcare centers and schools are located within five miles of over 100 EtO-emitting facilities.
• Specific geographic hotspots show severe health risks; in St. John the Baptist Parish, Louisiana, the combined cancer risk from ethylene oxide and chloroprene is more than 200 times the EPA's acceptable levels. In Willowbrook, Illinois, rates of Hodgkin's lymphoma among women were nearly 90 percent higher than state and county averages.
• The EPA's regulatory framework, including the Miscellaneous Organic Chemical Manufacturing (MON) rule, is criticized for allowing periodic uncontrolled releases and failing to mandate fenceline monitoring. Additionally, a 2020 EPA Office of the Inspector General report found the EPA failed to contact 65 percent of high-risk facilities.
• The FDA is tasked with identifying alternatives to EtO for medical sterilization, but recent updates suggest the agency is prioritizing the decrease of EtO use rather than a total phaseout.

APA

Union of Concerned Scientists (2021). What is Ethylene Oxide (EtO)? https://www.ucs.org/resources/what-ethylene-oxide-eto

Chicago

Union of Concerned Scientists. What is Ethylene Oxide (EtO)? 2021. https://www.ucs.org/resources/what-ethylene-oxide-eto.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=What is Ethylene Oxide (EtO)? |date=8 October 2021 |url=https://www.ucs.org/resources/what-ethylene-oxide-eto |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2021what, author = {{Union of Concerned Scientists}}, title = {{What is Ethylene Oxide (EtO)?}}, institution = {Union of Concerned Scientists}, year = {2021}, month = oct, url = {https://www.ucs.org/resources/what-ethylene-oxide-eto}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }