Ethylene oxide (EtO) serves various industrial purposes, notably medical equipment sterilization, but its carcinogenic and environmental risks demand rigorous pollution control. Addressing EtO pollution necessitates a multi-faceted approach involving stringent regulations, technological advancements, and collaborative efforts across commercial sterilization facilities and chemical plants.
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Understanding Ethylene Oxide Pollution
Ethylene oxide (EtO), a flammable colorless gas, finds widespread application in producing various products (notably antifreeze), but its primary and most common use is for sterilizing medical equipment and instruments sensitive to heat and radiation.
However, EtO is classified as one of 187 hazardous air pollutants under the U.S. Clean Air Act, and even low emission levels can pose long-term health risks, making it a significant air quality concern.
Short-term exposure to EtO can cause nausea, respiratory irritation, neurological effects, and lung injury. Chronic exposure is linked to increased cancer risk, reproductive effects, genetic mutations, and damage to the nerves, brain, and other organ systems.
Primary sources of EtO emissions include uncontrolled releases from industrial facilities, emissions during sterilizer chamber evacuation, and vaporization during the sterilization process at commercial sterilizer facilities.
Current Regulatory Framework for Ethylene Oxide
The U.S. Environmental Protection Agency (EPA) is taking steps to limit emissions and exposure risks under the authority of the Clean Air Act. This includes reviewing and updating regulations on acceptable EtO release levels for different industrial sectors.
The EPA has proposed the following actions to reduce the risks associated with EtO:
- Miscellaneous organic chemical manufacturing: In 2020, the EPA finalized requirements for the miscellaneous organic chemical manufacturing sector, referred to as "MON," to cut emissions of hazardous air pollutants by 107 tons per year, including a reduction of approximately 0.76 tons per year of EtO emissions.
- Reducing EtO commercial sterilizers: On April 11, 2023, the EPA proposed new regulations affecting 86 commercial sterilizers nationwide. If implemented, these requirements would decrease EtO emissions from commercial sterilizers by 80%, reducing risks to nearby communities.
- Hazardous organic national emission standards (HON): On April 6, 2023, the EPA announced a proposal to significantly reduce emissions of toxic air pollutants, including highly toxic chemicals like EtO, from chemical plants, as part of the hazardous organic national emission standards (HON).
- Interim decision on EtO pesticide use: On April 11, 2023, the EPA put forward a comprehensive set of protections under the Federal Insecticide, Fungicide, and Rodenticide Act to mitigate risks associated with EtO use for sterilization, safeguarding workers and communities near sterilization facilities.
The EPA has also strengthened emissions reporting requirements through the Toxics Release Inventory (TRI) analysis. Medical sterilization facilities and chemical plants using EtO must now disclose their emissions data, informing communities about exposure risks.
These regulatory actions are expected to curb EtO pollution significantly over the next decade.
Challenges and Concerns in Curbing Emissions
Despite the need for lower emissions, reducing EtO pollution faces several constraints. According to the American Chemistry Council, accurately measuring and monitoring EtO at the extremely low levels targeted by regulations is technically complex. The EPA itself acknowledges the difficulty.
There are also supply chain concerns, given EtO's widespread use in medical device sterilization. EtO is crucial for sterilizing over 50% of medical devices, and its absence may worsen healthcare-associated infections, deaths, and costs as no single alternative method can replace it entirely. These realities mean we must find ways to lower emissions without jeopardizing access to safe healthcare.
Due to varying priorities, industry and environmental advocates have divergent views on EtO emissions. Industry emphasizes cost reduction and economic interests, while environmental advocates stress public health and stringent regulations.
Concerns also arise about the feasibility of implementing the EPA's proposed 80% EtO reduction within 18 months and the potential for facility closures, which could lead to shortages of essential medical devices. Balancing these concerns requires considering scientific evidence and community input.
Alternative Solutions and Innovations for EtO Reduction
Alternative sterilization methods
Alternative sterilization methods to EtO include ionizing radiation (used in 45% of medical devices), heat sterilization (steam or dry heat), and non-industrialized methods such as vaporized hydrogen peroxide, chlorine dioxide, nitrogen dioxide, and peracetic acid. These alternatives have limitations and may take up to a decade for validation and industrialization.
Advanced emissions controls
Thermal oxidizers, catalytic converters, absorbers, and other systems can capture and destroy EtO before release into the air.
For example, Anguil's Catalytic Oxidizers, coupled with their peak shaver technology, achieve over 99% EtO destruction efficiency and maintain concentrations below one part per million. These integrated systems ensure safe EtO control by preventing leakage and using a high-efficiency gas-water contact method.
Real-time emissions monitoring
Sensor networks and analytical methods for continuously tracking EtO emissions enable early leak detection and rapid response.
The Emissions Monitoring System from Thermo Fisher Scientific, featuring MAX-iAQ and EMS-10 CEMS, offers precise real-time detection of low-level ethylene oxide emissions. It exceeds EPA standards with an LOD of 1 ppb and rapid response times, ensuring compliance and worker safety. With minimal maintenance and expert support, it safeguards indoor air quality for a secure and compliant workplace.
Collaboration and Information Sharing
Managing air quality involves the regulatory authorities and state, local, and tribal air agencies. Communities should have access to emissions data and information on health risks, with their input guiding policy decisions regarding acceptable exposure levels and timelines for reducing EtO emissions.
The EPA's TRI-national analysis offers crucial data on toxic chemical releases, including EtO. Recent decisions have broadened EtO reporting requirements for 29 facilities, improving transparency and awareness. This information is vital for safeguarding workers in sterilization facilities and nearby communities, enabling informed choices and environmental protection.
Various states in the U.S. have EtO regulations, with resources accessible through state environmental agencies and health departments. This collaboration promotes awareness, pollution mitigation, and community engagement to ensure air quality and safety.
The Path Forward
Mitigating the risks of EtO will require a concerted effort combining regulations, technological progress, industry initiative, and community partnership. Although challenges remain, emerging innovations provide promising pathways for reducing EtO emissions and protecting human and environmental health. Sustained efforts to optimize industrial processes, wider deployment of safer alternative sterilization methods, advanced emissions controls, and transparent public dialogue can drive meaningful progress.
Read More: Reducing Ethylene Oxide Emissions from Commercial Sterilization Facilities
References and Further Reading
American Chemistry Council. (2022). The Challenges of Ethylene Oxide Air Sampling. [Online]. Available at: https://www.americanchemistry.com/industry-groups/ethylene-oxide/resources/the-challenges-of-ethylene-oxide-air-sampling
Anguil. (2023). Staying Ahead of Evolving EtO Regulations. [Online]. Available at: https://anguil.com/news/staying-ahead-of-evolving-eto-regulations/
Economics & Statistics Department. (2019). The Economic Benefits of Ethylene Oxide and the Potential Cost of Deselection. [Online]. American Chemistry Council. Available at: https://www.americanchemistry.com/content/download/13643/file/Cost-of-Deselecting-Ethylene-Oxide.pdf
EPA. (2018). Ethylene Oxide. [Online]. Available at: https://www.epa.gov/sites/default/files/2016-09/documents/ethylene-oxide.pdf
EPA. (2023). Actions to Protect Workers and Communities from Ethylene Oxide (EtO) Risk. [Online]. Available at: https://www.epa.gov/hazardous-air-pollutants-ethylene-oxide/actions-protect-workers-and-communities-ethylene-oxide-eto
EPA. (2023). Hazardous Air Pollutants: Ethylene Oxide (EtO). [Online]. Available at: https://www.epa.gov/hazardous-air-pollutants-ethylene-oxide
EPA. (2023). TRI National Analysis-Ethylene Oxide. [Online]. Available at: https://www.epa.gov/trinationalanalysis/ethylene-oxide
EPA. (2023). What EPA Is Doing to Address Ethylene Oxide (EtO) and to Learn More About the Chemical. [Online]. Available at: https://www.epa.gov/hazardous-air-pollutants-ethylene-oxide/what-epa-doing-address-ethylene-oxide-eto-and-learn-more
Healey, N. (2020). What's the solution to the ethylene oxide crisis? [Online]. Available at: https://www.medicaldevice-network.com/features/ethylene-oxide-sterilisation/?cf-view
Reiss, R., Ong, K., Sauer-Budge, A., Vargas, J., & Villarraga, M. (2023). EPA Aims to Reduce EtO Emissions at Medical Device Sterilization Facilities. [Online]. Available at: https://www.exponent.com/article/epa-aims-reduce-eto-emissions-medical-device-sterilization-facilities
Thermo Fisher Scientific Inc. (2023). Ethylene Oxide Monitoring System-Compliance with confidence using real-time EtO emissions monitoring. [Online]. Available at: https://www.thermofisher.com/pk/en/home/industrial/environmental/air-quality-analysis/ethylene-oxide-eto-emissions-monitoring.html
Waterson, S. (2022). Ethylene Oxide Monitoring Challenges. [Online]. Available at: https://www.epa.gov/system/files/documents/2022-10/Waterson_Sara_for%20posting.pdf
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