EPA Proposes to Rescind, Revise Restrictions on Ethylene Oxide Emissions
A proposed rule published March 17 in the Federal Register would amend EPA’s National Emission Standards for Hazardous Air Pollutants (NESHAP) as they pertain to commercial sterilization facilities’ use of ethylene oxide (EtO). The proposal would rescind some requirements and revise others that EPA adopted in 2024 based on what the agency now describes as an incorrect interpretation of the Clean Air Act.
Commercial sterilization facilities use EtO to sterilize or fumigate materials such as medical equipment and supplies. Both EPA and the U.S. National Toxicology Program have determined that EtO is a human carcinogen. The Agency for Toxic Substances and Disease Registry (ATSDR) states that workers who perform sterilization may be exposed to relatively high levels of EtO and may experience headaches, memory loss, numbness, nausea, and vomiting.
In 2024, an EPA final rule amended NESHAP to address emissions from building leaks and sterilization chamber vents, require facilities to use continuous emissions monitoring systems, and ensure that emissions standards apply to sterilization processes when they start up, when they shut down, and when they malfunction.
According to EPA’s current proposed rule, the 2024 requirements stemmed from a “residual risk review” that the agency incorrectly used to impose additional regulatory burdens. EPA now holds that the Clean Air Act allows the agency to use residual risk reviews only for the purpose of considering whether new regulatory standards are necessary. “This interpretation better reflects the structure of [Clean Air Act] section 112, which Congress deliberately designed with detailed implementation timelines and requirements that cannot be squared with the assertion of authority to revisit residual risk reviews on an ad hoc, category-by-category basis,” the proposed rule states.
The proposal would rescind the NESHAP standards finalized in 2024 for commercial sterilization facilities as well as the requirement that the facilities use “permanent total enclosures” to ensure complete capture of EtO. EPA’s proposal would also revise the 2024 rule so that EtO emissions requirements would no longer apply to commercial sterilization facilities that use the substance in quantities of 30 or fewer tons per year.
While the 2024 rule required most commercial sterilization facilities to use a continuous monitoring system, or CEMS, for EtO, the new proposal would allow facilities to choose between CEMS and parametric monitoring.
For more information, refer to the notices in the Federal Register for the current proposed rule and the 2024 final rule; the EPA press release for the proposed rule; and the ATSDR toxicological profile for EtO.
Related: An industrial hygienist from a consulting firm that participated in the sampling of EtO in the Willowbrook, Illinois, community discussed his experiences as part of a prerecorded virtual session at the AIHA conference in 2020. The case drew national attention and resulted in the shuttering of a Willowbrook facility.