EPA Asserts Agency Overstepped Its Authority by Revising Emission Standards for Ethylene Oxide Pollution

Ethylene oxide is a cancer-causing hazardous air pollutant that is used to sterilize medical products, among other things – we’ve blogged about ethylene oxide pollution several times. 

Because the U.S. Environmental Protection Agency (EPA) has moved the sticks on regulating ethylene oxide pollution yet again, it’s time for another update.

EPA on March 17 published a proposed rule and reconsideration of its April 5, 2024 Final Rule that revised the National Emission Standards for Hazardous Air Pollutants (NESHAPs) for facilities that use ethylene oxide to sterilize medical and other products. 

The 2026 proposed rule would undo some, but not all, of the stricter emission standards imposed by the 2024 rule, mostly having to do with facilities that use 10 or more tons per year of ethylene oxide. 

There are no such facilities in our region, although one facility in Erie uses smaller quantities of ethylene oxide. It appears that the emission limitations that apply to that facility will not change as a result of EPA’s latest proposed revisions to the NESHAPS.

What makes the latest proposed rule interesting is the basis that EPA asserts for promulgating it: specifically, that EPA lacked the authority to perform the residual risk review on which it based the revisions it made in 2024 and proposes to rescind now, because that was the second residual risk review it performed for the NESHAPs for ethylene oxide.

 In other words, EPA is now claiming that some of the revisions that it made in 2024 to the NESHAPs for ethylene oxide broke the law.

Did they?  Maybe.

Some background on what the Clean Air Act says (and does not say) about revising NESHAPs will be helpful to understanding why (or why not):

The Act requires that within eight years after promulgating a NESHAPs, EPA must revisit it to determine whether it is sufficiently stringent. First, EPA must perform a technology review to determine whether the standard incorporates what’s known as developments in practices, processes, and control technologies, and revise the standard to incorporate such developments if it does not. 

The Act further requires that EPA perform an additional technology review every eight years thereafter.

The Act also requires that within eight years of promulgating a NESHAPs, EPA must perform a residual risk review to determine whether the NESHAPs should be revised to address any health risks that remain despite the NESHAPs. 

The Act does not expressly require that EPA perform further residual risk reviews every eight years as it does for technology reviews. In fact, it does not say anything about additional residual risk reviews.

EPA first promulgated a NESHAPs for sterilization facilities that use ethylene oxide in 1994 and finalized technology and residual risk reviews for it in 2006. When EPA proposed the 2024 revisions to the standards, it took the position that it was permitted to do a second residual risk review because the Clean Air Act did not expressly prohibit such a review (which was a novel position for it to take). 

EPA now claims that it can only exercise authority that is provided by the statute (rather than authority that is not prohibited by the statute), and that the Clean Air Act does not provide it with the authority to do additional residual risk reviews for a NESHAPs.

“This is another question that will be determined by the federal courts,” said GASP Senior Attorney John Baillie. “It is unlikely that Congress will clarify what authority it intends for EPA to have, although it should. EPA does itself no favors by flip-flopping every several years.”

EPA has scheduled a virtual public hearing for its proposed revisions to the ethylene oxide NESHAPs for April 1, 2026, with details to be announced at this address:  https://www.epa.gov/ stationary-sources-air-pollution/ ethylene-oxide-emissions-standards- sterilization-facilities. 

Further, EPA is accepting comments on the proposed revisions through May 1.  You may submit your comments at https://www.regulations.gov/, under Docket ID No. EPA-HQ-OAR-2019-0178.