What is Ethylene Oxide? Answers to Your Questions about the Cancer

You may have heard about the chemical, ethylene oxide (EtO), making headlines lately for posing health risks to communities across the country. EPA recently issued information on 23 locations in the country that are experiencing very high rates of exposure to ethylene oxide from nearby facilities that use it to sterilize medical equipment. If you live, work, or learn near any of these facilities, you probably have a long list of questions about the chemical, about EPA's intended actions to require emission reductions, and about how you can get involved to advocate for health-protective decisions. I’ve compiled some information to get you started.

EtO is a flammable, colorless gas used to sterilize medical equipment and other plastics that are sensitive to heat or moisture and as antimicrobial treatment for spices. The US Food & Drug Administration (FDA) estimates that EtO is used to sterilize about half of all medical equipment, including bandages, sutures, and stents. It is also used to make other component chemicals in products ranging from plastics to antifreeze. Its chemical properties make it especially good at killing viruses, bacteria, and human cells by reacting with proteins, DNA, and other essential cellular components.

The US Environmental Protection Agency (EPA), the National Toxicology Program, and the International Association of Research on Cancer classify EtO as a substance that can cause certain cancers.

Chronic exposure to EtO— inhaled throughout a person's life— is associated with the development of cancers of the white blood cells, such as non-Hodgkin lymphoma, myeloma, and lymphocytic leukemia. Studies have also shown a relationship between EtO exposure and breast cancer in women. Also, because EtO is mutagenic—meaning it can change a cell's DNA—children may be especially susceptible to its effects. Workers in facilities that produce and use EtO as well as people living near facilities that release it into the atmosphere are at risk of unsafe exposures even when the facilities are using the best available technologies to handle and contain it.

If you live near a facility emitting EtO into the air, whether it's a plant sterilizing medical equipment or chemical facility making plastics, you may be exposed to the chemical depending on your exact location and how much the facility releases. Facilities release ethylene oxide in two ways: from the smokestack (which is usually tracked by the company) and through fugitive emissions (unintentional emissions through valves, leaky pipes, doors, windows and other openings).

You can find the exact locations of sterilizer facilities emitting unsafe levels of EtO at EPA's website and you can check whether chemical plants or sterilizer facilities near you report releases of EtO into the air using EPA's Toxics Release Inventory tracker. EPA's AirToxScreen uses the National Air Toxics Assessment to offer a location-based screening tool that shows long-term cancer and health risks given air emissions of hazardous chemicals over a person's lifetime.

Reacting to the high cancer risk posed to communities near EtO-emitting facilities, the EPA began working to review its emissions requirements for two types of facilities regulated under the agency's authority from the Clean Air Act section on hazardous air pollutants: chemical facilities known as "Miscellaneous Organic Chemical Manufacturing (MON)," and commercial sterilizers.

EPA proposed changes to its MON rule in 2019, regulating toxic emissions for about 200 chemical plants that produce solvents, plastics, and pesticides across the country. So-called MON facilities are especially concentrated in EPA's Region 6 in Texas and Louisiana, and disproportionately affect communities of color and low-income communities.

Since 2019, a Texas state agency and its industry partners have been actively working to challenge the Environmental Protection Agency's (EPA) science on the harms of ethylene oxide. In 2020, the notoriously industry-friendly Texas Commission on Environmental Quality (TCEQ), along with the industry trade association American Chemistry Council and the firm Huntsman Petrochemical, submitted a petition to the EPA claiming that the work of EPA scientists is suspect. This group pressed the EPA to support the adoption of a far less protective standard based on the TCEQ's analysis. The EPA's final rule, issued in 2020, required technological fixes to reduce EtO emissions but continued to allow periodic, uncontrolled releases of chemical pollution and fugitive emissions into communities without monitoring. After the rule was issued, UCS joined 10 community, scientist, environmental, and environmental justice groups represented by Earthjustice on a petition for its reconsideration. EPA formally rejected TCEQ's petition earlier this year and, after hearing from community members, scientists, and the public about the need to use its more health-protective value, the agency proposed plans to use EPA science in future ethylene oxide emissions decisions.

The EPA also plans to issue a rule by the end of 2022 with strengthened emissions requirements for approximately 100 commercial sterilizer facilities across the country. A recent EPA webinar goes into detail about this upcoming effort, which is long overdue.

EPA is also coordinating with the Occupational Safety and Health Administration (OSHA) to determine how it can better protect workers’ health as part of the agency's review of EtO as a registered pesticide.

For each of these separate governmental rulemaking processes, public comments will be accepted, and all substantive comments are required by law to be considered by the agency.

The Food and Drug Administration (FDA) has also acknowledged that it has a role to play in identifying alternatives to EtO for sterilizing medical equipment. In 2019, it announced two innovation challenges in which FDA would work closely with companies to identify safe and effective alternative approaches to EtO use and the development of strategies to reduce emissions from the EtO sterilization process.

Despite FDA's innovation challenge, the agency's recent press release suggests that it believes that EtO cannot be completely replaced as a sterilization method for many medical devices at this stage.

There are, however, some promising alternatives that could be used in place of ethylene oxide. FDA needs to continue to prioritize the development of methods for sterilization processes including using radiation, vaporized hydrogen peroxide, and vaporized paracetic acid to help ease the transition away from ethylene oxide and make our communities safer.

First, you should see if there's already a community-led organization working in your area to advocate for stronger protections at the local, state, and/or federal level.

You can also reach out to federal agencies with your concerns. EPA is doing community outreach in communities most impacted by sterilizer-caused EtO emissions and you can find more details at the agency's website about how to engage. The Agency for Toxic Substances and Disease Registry (ATSDR) can also help answer questions about associations between EtO exposure and health conditions based on the best available evidence; you can send questions via email to [email protected]. If you have concerns about your child's health as a result of potential exposure to EtO, you can talk to your healthcare provider and reach out to a local Pediatric and Environmental Health Specialty Unity (PEHSU) expert here.

EPA plans to issue a Clean Air Act rulemaking for commercial sterilizers later this year and for other chemical facilities soon, as well. UCS will be putting out resources for engaging in the comment periods for those rules, so sign up for our listserv or text SCIENCE to 67369 and stay tuned for more information from us coming soon on this public health issue.

Posted in: Science and Democracy

Tags: Chemical Safety, Environmental Justice, EPA, ethylene oxide

About the author

Genna Reed is the director of policy analysis in the Center for Science and Democracy at the Union of Concerned Scientists. In her role, she leads research on political and corporate influences on science-informed decision making—working to inform the public about issues where science is stifled or obscured, and to ensure that federal, state, and local policies are based on rigorous, independent science.

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