What EPA Is Doing to Address Ethylene Oxide and to Learn More About the Chemical

As EPA pursues its mission to protect human health and the environment, addressing ethylene oxide (EtO) is a priority for the Agency. While EPA regulates EtO under a number of different environmental laws, the Agency’s current efforts to reduce this chemical’s impact fall into two main categories: air emissions of EtO and use of EtO as a pesticide.

EPA is reviewing its current air regulations that limit the amount of EtO certain types of industries release into the outdoor air to determine whether legal standards for EtO emissions to air can be further strengthened.  There are ways industry can reduce emissions, and EPA is working with state, local and tribal air agency partners and with companies to identify opportunities to reduce emissions faster than national regulations can achieve.

The Agency also is developing pesticide risk reduction requirements to protect workers who use EtO and people who live in surrounding communities. In addition, EPA regularly provides state agencies information on measuring EtO in air. The Agency also is conducting and supporting research to improve our ability to measure EtO content in outdoor air.

EPA is reviewing Clean Air Act regulations for industries that emit EtO into the air

Since 2018, as part of a two-part approach to reduce EtO emissions, EPA has been reviewing its Clean Air Act regulations for facilities that release the chemical to the outdoor air. These types of regulations are known as National Emissions Standards for Hazardous Air Pollutants, or NESHAP. Hazardous air pollutants also are known as “air toxics.”

The Agency has started its review with two rules:

1. The air toxics rule for Miscellaneous Organic Chemical Manufacturing, often called “the MON.”

This rule applies to plants that manufacture chemicals.  After conducting a “risk and technology review,” EPA published a final rule in August 2020 that requires additional controls on certain equipment and processes that emit ethylene oxide to reduce risk to surrounding communities and protect public health.

Many chemical plants are covered by multiple air toxics rules. Read the MON.

2. The air toxics rule for Ethylene Oxide Commercial Sterilizers.

As directed by the Clean Air Act, EPA regulates emissions of EtO from many commercial sterilizers. The Agency is reviewing this rule, which was established in 1994 and last updated in 2006. A technology review of the rule, which is required by law, is due. During a technology review, EPA will examine developments in practices, processes and control technologies since 2006, considering cost and feasibility, as well as address any previously unregulated emission points. As part of the current review for this rule, EPA has taken a number of steps necessary to develop a proposal, including obtaining data and information on emissions of EtO, equipment configuration and processes, and possible control strategies. In addition, because nearly one-quarter of the sterilizers subject to the rule are small businesses, EPA was required by law to convene a Small Business Advocacy Review Panel, which includes conversations with small entity representatives to understand the potential impacts of the rule on small businesses. EPA completed this small business engagement in April 2021. When EPA issues a proposed rule, the Agency makes it available to the public, so that the public will have the opportunity to review it and submit comments. EPA expects to issue a proposal in 2022. Read more information about Ethylene Oxide Emissions Standards for Sterilization Facilities.

The Agency has also started work to review its rules for several additional chemical sector source categories, including Synthetic Organic Chemicals Manufacturing Industry, Polyether Polyols Production, and Chemical Manufacturing Area Sources. These are complex rulemakings, which can take several years to complete.

EPA is working with state air agencies to reduce EtO emissions

The responsibility for managing air quality in the U.S. is shared by EPA and state, local and tribal air agencies. Several states are working to address EtO in their jurisdictions – often faster than what EPA’s rulemaking process can accomplish. For example, in Georgia, the state worked with two commercial sterilizers in the Atlanta area, which have installed equipment to significantly reduce EtO emissions. In Illinois, a commercial sterilizer installed state-of-the art pollution controls as required by a new state law. And in Missouri, a commercial sterilizer is voluntarily installing pollution controls. EPA has provided technical support to air agencies as part of this work. In addition, EPA is coordinating with air agencies to share information with communities about the risks from long-term exposure to EtO in the outdoor air.

EPA is working to reduce EtO’s impact on workers

While OSHA is the federal agency that protects workers from exposures to harmful substances in their workplace, EPA also is working to reduce the impact of EtO on workers by reevaluating the terms of the registration for use of EtO as a sterilant, which is considered a type of pesticide.

Pesticide labels, which are part of a pesticide registration and are legally binding under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), carry directions and precautions that define who may use a pesticide, as well as where, how, how much, and how often it may be used. Failure to follow the label is a violation of federal law. EPA’s Office of Pesticide Programs 2020 draft risk assessment for ethylene oxide concludes that EtO poses inhalation risks of concern and that additional mitigation measures are necessary to protect workers' health and surrounding communities.

EPA considers EtO critical for sterilizing medical equipment and necessary to protect public health. According to the Food and Drug Administration (FDA), EtO is the only sterilization method available for many medical devices. Approximately 50 percent of all medical devices are treated with EtO in the United States annually. EtO treatment is also a principal method used to sterilize herbs and spices. The spice industry estimated that approximately 32 percent of herbs and whole spices are treated with EtO annually.

Mitigating risks to human health is a focus of EPA’s pesticide registration review of EtO. Currently, EtO labels require that workers wear protective clothing and respiratory protection. The proposed interim decision, which is the next step in the registration review process, will propose additional specific, detailed measures for reducing workers’ and communities’ exposure to EtO. The public will have an opportunity to comment on the proposed decision.

All documents related to EPA’s assessment of EtO’s use as a pesticide are available in docket EPA-HQ-OPP-2013-0244 on www.regulations.gov. Learn more about EPA's assessment of EtO's use as a pesticide.

Improving our understanding of EtO and the tools to help us learn more about it

Current air monitoring efforts

In recent years, several state air agencies have conducted air monitoring for EtO near known industrial sources that release EtO to the outdoor air. EPA has confidence in the results of EtO monitoring at higher concentrations -- concentrations that are well above the minimum level of EtO that the current measurement methods can detect. This includes concentrations like those measured immediately downwind of industrial sources that do not have state-of-the-art control technology in place.

EPA and other agencies also are monitoring for EtO at a number of locations in two longstanding monitoring networks that are used to track trends in toxic air pollutants (these networks are not focused on particular industrial sources). Some results of this monitoring, however, have shown much lower concentration values—closer to the method detection level—and EPA is less confident in these data. While these lower levels of EtO suggest there is a “background” level of EtO in the outdoor air, EPA is not yet certain about exact background EtO levels due to uncertainty with current measurement methods. Learn more about EPA's work in understanding background levels of Ethylene Oxide.

Conducting research to better understand and measure EtO

EPA is researching ways to improve our ability to measure EtO in the outdoor air. This research will help improve measurement at the source of EtO emissions (such as industrial facilities) and measurement of EtO concentrations in the outdoor air.  Understanding how much EtO is in the air and where is an important step to helping communities have a better understanding of their risk and to reducing emissions to protect health. It also will help us determine potential origins of background EtO. The objectives for this research are to:  

• Enable measurement of EtO at various levels, including at concentrations lower than what are currently possible to measure at the source of EtO emissions and in the outdoor air.
• Provide real-time testing capability to measure EtO on a continuous or near continuous basis, compared to 12- and 24-hour testing capabilities with the current method.
• Measure EtO in areas of interest to identify potential sources.   
• Improve modeling capabilities to better understand how EtO interacts with other air pollutants in the atmosphere and estimate the movement and distribution of EtO in the environment.   

Expanding reporting requirements for sterilization facilities

EPA is committing to broadening Toxics Release Inventory (TRI) reporting on EtO to include certain contract sterilization facilities that use EtO that are not currently required to report this information to EPA. TRI is a resource for learning about annual chemical releases, waste management, and pollution prevention activities reported by nearly 21,000 industrial and federal facilities. 

Workers in contract sterilization facilities that use EtO and communities – including historically underserved communities – living near these facilities are potentially at the highest risks of being exposed to EtO. Making more information available about releases of EtO will inform the communities that live near these facilities and will assist the agency in identifying and responding to any human health and environmental threats such releases may cause.  Having to report releases to TRI makes companies more aware of their use and emission of pollutants, and can lead companies to find ways to reduce those emissions.