US EPA Proposes Weakening Ethylene Oxide Emission Limits

Overview

The United States Environmental Protection Agency (US EPA) has proposed weakening its air pollution limits for ethylene oxide emissions from commercial sterilisation facilities. The proposal effectively dismantles a 2024 rule that mandated significant reductions in emissions of this known carcinogen from medical equipment sterilisation plants. The rollback removes requirements for continuous fenceline air monitoring and relaxes the emission reduction targets that were designed to protect communities living near these facilities.

While this is a US regulatory development, it carries direct implications for Australian environmental consultants, health risk assessors and air quality modellers. International regulatory standards frequently inform Australian assessment methodologies, and changes to US EPA positions on carcinogenic compounds create uncertainty in how Australian practitioners should benchmark their assessments.

Key details

Ethylene oxide (EtO) is a colourless, flammable gas widely used to sterilise medical devices and equipment that cannot withstand heat or steam sterilisation. It is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC) and is linked to lymphoid cancers, breast cancer and leukaemia.

The 2024 rule, issued under the US Clean Air Act’s National Emissions Standards for Hazardous Air Pollutants (NESHAP), required commercial sterilisation facilities to reduce their ethylene oxide emissions by approximately 90 per cent. A key feature was the requirement for continuous fenceline monitoring, which would have provided real-time data on ambient EtO concentrations at facility boundaries. This represented a high benchmark for verifying point-source emission controls.

The proposed rollback cites industry concerns about compliance costs and potential disruption to the medical device supply chain. Sterilisation industry groups argued that the 2024 requirements were technically infeasible for many smaller facilities and would force closures, creating shortages of sterilised medical equipment.

The US EPA’s revised proposal removes the continuous fenceline monitoring requirement and extends compliance timelines, effectively allowing facilities to continue operating at higher emission levels for an extended period.

Australian context

Australia does not have a direct equivalent to the US NESHAP framework, but ethylene oxide emissions are regulated under state-based environmental protection legislation. In New South Wales, the Approved Methods for the Modelling and Assessment of Air Pollutants in NSW provide the technical framework for assessing industrial air emissions. In Victoria, the Environment Protection Authority applies the Environmental Reference Standard, while Queensland relies on its Environmental Protection (Air) Policy.

Australian practitioners conducting Human Health Risk Assessments (HHRAs) for industrial facilities regularly reference international toxicological databases, including the US EPA’s Integrated Risk Information System (IRIS). When the US EPA adjusts its toxicity assessments or acceptable exposure thresholds for compounds like ethylene oxide, it creates a ripple effect through the reference values used in Australian assessments.

Ethylene oxide is used in Australian industrial applications, including sterilisation of medical devices and certain food processing operations. Facilities handling EtO are subject to licensing requirements under state EPA frameworks. Any shift in international regulatory consensus on acceptable exposure levels may prompt Australian regulators to review their own guideline values and assessment approaches.

The removal of fenceline monitoring requirements in the US is also notable. Australian regulators have been moving towards more robust ambient air monitoring requirements for licensed facilities, particularly in Western Sydney, the Hunter Valley and industrial zones in Melbourne’s west. A retreat from continuous monitoring in the US may slow the adoption of similar requirements in Australia.

Practical implications

For Australian environmental consultants and air quality specialists, this development raises several practical considerations:

• Health risk assessments: Practitioners currently preparing HHRAs for facilities that use or store ethylene oxide should document which toxicological reference values they have adopted and the basis for their selection. If US EPA values are revised downward, assessments relying on current values may need to be updated.
• Air quality modelling: Consultants modelling EtO emissions from Australian sterilisation facilities should consider conducting sensitivity analyses to understand how changes in acceptable ambient concentrations would affect their risk characterisation outcomes.
• Regulatory submissions: When preparing environmental impact statements or licence applications for facilities that emit ethylene oxide, practitioners should acknowledge the evolving international regulatory landscape and demonstrate that their assessment reflects the most current and protective guideline values available.
• Community engagement: For facilities located near residential areas, the shifting international debate about acceptable EtO exposure levels may increase community concern. Proactive communication strategies and transparent monitoring programs can help manage stakeholder expectations.
• Due diligence: Property transactions involving current or former sterilisation facilities should include assessment of potential EtO contamination of indoor air, ambient air and surrounding soil and groundwater.

References and related sources

• AP News: US EPA proposes weakening ethylene oxide emission limits
• US EPA: Ethylene oxide hazardous air pollutant information
• IARC Monographs: List of Classifications
• NSW EPA: Approved Methods for modelling and assessment of air pollutants

How iEnvi can help

iEnvi provides specialist contaminated land and environmental risk assessment services, including air quality assessments and human health risk assessments for industrial facilities. Our team can assist with due diligence investigations for properties with potential ethylene oxide exposure, regulatory submissions for licensed facilities and remediation planning for sites impacted by volatile organic compounds. We also offer expert witness services where environmental disputes require independent technical opinion.

This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.

Need advice on this topic? Speak to an iEnvi expert at hello@ienvi.com.au or 1300 043 684, or contact us online.