Insights & Events

As we previously predicted, the Trump Administration continues to advance a number of regulatory initiatives, one of which is ethylene oxide (EtO) emission standards, a critical focus of our EtO practice area. On March 13, 2026—a year after the Trump administration announced its intent to reconsider the 2024 National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Ethylene Oxide Commercial Sterilization Facilities (40 CFR Part 63, Subpart O)—the Environmental Protection Agency (EPA) proposed to rescind and revise the emission standards set forth in the 2024 Final Rule. Less than two years ago, the 2024 Final Rule introduced heightened control requirements to reduce ethylene oxide emissions by more than 90 percent on a very short timeline, including “total enclosure” of the entire facility. To comply, some sterilization facilities had to install expensive control equipment by April 2026. The reconsideration proposal follows President Trump’s July 2025 proclamation extending by two years the 2024 Final Rule compliance deadlines for facilities that stated they could not meet the initial deadlines.

If finalized, EPA’s newly proposed amendments would chart a different path forward by: (1) revising standards applicable to new aeration room vents (ARVs) at facilities that use more than 10 tons of ethylene oxide per year to match the requirements for existing ARVs; (2) allowing facilities to choose between parametric monitoring or continuous emission monitoring systems (CEMS) to demonstrate compliance; (3) eliminating the permanent total enclosure (PTE) requirement; and (4) removing specific control categories that were added by the 2024 Final Rule (referred to as the “risk-based standards”), on the grounds that EPA lacked authority to conduct the risk review that formed the basis of those new standards under section 112(f)(2) of the Clean Air Act (CAA).

EPA asserts that the 2024 Final Rule “did not follow the CAA and [was] based on outdated science.” In support of its new proposal, the agency highlighted supply chain concerns and the importance of ethylene oxide to the medical community, recognizing that it “is the only safe and effective sterilization method available for many life-saving medical equipment[s]” and that “[c]ommercial sterilizers utilize EtO to sterilize 50 percent of all medical devices in the U.S. every year—or 20 billion medical devices—with no viable alternative on the market.”

Notably, it also appears EPA is considering additional changes in the EtO space and, potentially, the reversal of other prior regulatory decisions. For example, EPA’s proposal questions its 2016 Integrated Risk Information System (IRIS) risk value for ethylene oxide, which purportedly estimated the increased cancer risk from inhalation exposure and triggered nationwide litigation. This contradicts EPA’s position in its December 2022 final action, in which the agency rejected an alternative risk value and confirmed its decision to rely on the 2016 EtO IRIS value in the risk assessment for the Miscellaneous Organic Chemical Manufacturing NESHAP (2020 MON final rule), as we discussed here. Now, EPA notes that different models and statistical estimates “could have resulted in an EtO IRIS value that [would be] up to five times lower (i.e., EtO is five times safer than the 2016 EtO IRIS value provided).” Therefore, EPA stated that “it would not be appropriate to rely on the 2016 EtO IRIS value in setting standards,” and explained its intent to re-analyze the IRIS value based on new statistical methods and scientific studies, including analyses regarding the impact of model selection. This, of course, is an argument we (and others) have been making on behalf of our clients all along.

While the new rule is not yet final, it is clear that regulators are revisiting standards and risk assessments related to ethylene oxide, which could markedly impact facility operations and litigation strategy. Companies with actual or potential EtO litigation exposure should keep abreast of this shifting environmental regulatory landscape.

— By Aleksandra Rybicki and Alexa Halkias