Ethylene Oxide (EtO)


The U.S. Environmental Protection Agency (USEPA) began the latest study of air toxic emissions across the United States using data from 2014. That data was compiled and released by the USEPA in 2018 in a report called the National Air Toxics Assessment (NATA). The NATA is used as a screening tool to help identify areas of the country that require additional studies to better understand potential public health risks due to air toxic emissions.

The USEPA updated the toxicity value of EtO in 2016, and as a result, NATA’s screening-level estimates showed long-term exposure risks to EtO are greater than previously thought. This caused state agencies, including the West Virginia Department of Environmental Protection (WVDEP), to re-assess EtO emissions and impacts in areas identified by NATA as potentially highly impacted.

The WVDEP is committed to staying engaged nationally as the USEPA works to update regulations to reduce impacts from hazardous air pollutant emissions like EtO. The WVDEP is continuing to work with West Virginia facilities and communities to reduce the potential health risks associated with air toxic emissions.

Subscribe to EtO Updates

The West Virginia Department of Environmental Protection is committed to staying engaged as the U.S. EPA works to update regulations to reduce impacts from Ethylene Oxide. This mailing list is being developed to communicate information to interested parties in West Virginia.


  • Monitoring: The WVDEP is scheduled to begin fenceline monitoring at EtO-emitting sites in the Kanawha Valley by the end of January 2022. The expected project timeline for the sampling is available on page 19 of the Quality Assurance Project Plan (QAPP), located in the Monitoring Resources list below.

  • Upcoming Public Meetings: The WVDEP is attempting to schedule an in-person public meeting for Spring 2022. Please note that an in-person meeting is largely dependent on public health and safety protocols stemming from the COVID-19 pandemic.

To receive updates from the WVDEP regarding the monitoring project, upcoming public meetings, and other matters related to Ethylene Oxide in the Kanawha Valley, please sign up for our EtO Mailing List. More information about EtO and the steps the WVDEP and EPA have taken to address the issue is below.

What is Ethylene Oxide (EtO)?

Ethylene oxide (EtO) is a flammable, colorless gas used to make a range of products, including antifreeze, textiles, plastics, detergents and adhesives. EtO also is used to sterilize equipment and plastic devices that cannot be sterilized by steam, such as medical and dental equipment.

According to the Centers for Disease Control and Prevention (CDC), environmental exposures to EtO may also include vehicle exhaust and tobacco smoke.

The Clean Air Act lists EtO as one of 187 hazardous air pollutants (HAP), commonly referred to as air toxics.

What is the National Air Toxics Assessment (NATA)?

The NATA is USEPA's ongoing review of air toxics in the United States. It serves as a screening tool for state, local and tribal air agencies to help identify which pollutants, emission sources, and/or localized areas should be studied further to better understand possible public health risks.

The NATA calculates air toxics concentrations and long-term health risks for identified areas called “census tracts.” The most recent NATA report, which used 2014 data, identified 106 census tracts in the United States with an estimated cancer risk greater than 100 in 1 million. This means there’s a likelihood that 100 in 1 million people (or 1 in 10,000 people) would develop cancer if they breathed air containing the same amount of the same air pollutant every day for 70 years. The primary risk in many of these census tracts is driven by emissions of EtO.

In West Virginia, the NATA identified four census tracts with a total cancer risk greater than 100 in 1 million. All four tracts were in the Institute and South Charleston areas.

For more information related to the 2014 NATA, please see USEPA’s 2014 NATA Fact Sheet.

What Are the Health Risks of EtO?

According to the USEPA, short-term inhalation exposure to high concentrations of EtO can cause headache, dizziness, nausea, fatigue, respiratory irritation and, in some cases, vomiting and other types of gastrointestinal distress. Long-term exposure can irritate the eyes, skin, throat, and lungs, and harm the brain and nervous system, causing headaches, memory loss, and numbness.

Studies show breathing air containing elevated levels of EtO over many years can increase the risk of some types of cancers. Workers exposed to EtO are associated with an increased risk of cancers of the white blood cells, as well as an increased risk of breast cancer in females.

It is important to recognize that each type of cancer has its own risk factors, some of which are better understood than others. It is very rare that a specific cause can be found for any particular case of cancer. More information is available on the CDC’s Agency for Toxic Substances and Disease Registry (ATSDR).

It should be noted that the West Virginia Department of Health and Human Resources’ Bureau for Public Health (BPH) conducted an initial assessment of the cancer registry for the areas of concern in Institute and South Charleston in December 2019 and did not identify elevated levels of the cancers associated with EtO in these areas.

What is USEPA Doing to Reduce EtO Nationally?

The USEPA regularly reviews Clean Air Act regulations for facilities that emit hazardous air pollutants, including EtO, to ensure that they protect the public from significant risk. In addition, they are beginning work to review other regulations for facilities that emit EtO.

The following existing federal rules addressing industries using or producing EtO are under review for updates, with their anticipated final date:

  • Commercial sterilizers, 2022

  • Hospital sterilizers, 2023

  • Group 1 polymers and resins (neoprene), 2024

  • Synthetic organic chemicals manufacturing industry, 2024

  • Polyether polyols production, 2024

  • Chemical manufacturing area sources, 2024

What is DEP Doing to Address the Concerns of EtO?

The WVDEP is partnering with the USEPA, facilities that use EtO, communities, and other stakeholders to further identify and evaluate the sources of EtO emissions in West Virginia. The department’s efforts include:

  • Reached out to the West Virginia Department of Health and Human Resources’ Bureau for Public Health (BPH), who did an initial assessment of the cancer registry for the areas of concern in Institute and South Charleston. BPH has not identified elevated levels of the cancers associated with EtO in these areas.

  • Gathered updated EtO emissions data and meteorological information at sites emitting EtO.

  • Performed significantly more detailed site-specific emissions modeling than had been done by the USEPA.

  • Coordinating with the facilities to conduct short-term fence line monitoring over the coming weeks in the South Charleston and Institute areas.

  • Collecting 2020 emissions data to update modeling and identify potential emissions reductions strategies.

  • Requested that USEPA reevaluate and update the regulations that govern EtO sources in West Virginia.

  • Continuing to enforce existing state and federal regulations, and permits, including those relating to EtO emissions.

  • Hosted meetings with officials from the facilities and met with local/elected officials in the Kanawha Valley on August 10, 2021.

Virtual Community Meeting About Ethylene Oxide

The U.S. Environmental Protection Agency (EPA) has determined that the chemical compound, ethylene oxide, poses significantly more risks to human health than previously thought. That compound is used at the Union Carbide, International Flavors and Fragrances/Specialty Products, and Covestro LLC chemical production facilities at Institute and South Charleston, WV. EPA and the WV Department of Environmental Protection (WVDEP) held a virtual meeting to provide members of the communities located near those facilities with information about ethylene oxide and its known health effects.

The WVDEP and U.S. EPA Region 3 held a virtual public meeting on Thursday, September 23, 2021 from 6 to 8 p.m. to provide provide details on EtO and the upcoming monitoring and modeling and to answer questions.


Documents and Resources


The WVDEP has developed a short-term monitoring plan to obtain real-time ambient concentrations near EtO-emitting facilities in the South Charleston and Institute areas, which has been approved by the EPA and details are available in the monitoring resources list. Once funding is approved by and secured from the EPA, the WVDEP will initiate the sampling.

To the extent possible, the monitoring will occur when most EtO-emitting processes are in operation at these facilities. The facilities will provide EtO emissions data and on-site meteorological data during sampling.

Once the monitoring is complete, the samples will be analyzed and put through a Quality Assurance Quality Control (QA/QC) process, and results will be posted to this page. After additional analyses, a final report - including both monitoring and modeling reviews - will be provided.

Monitoring Resources

Unknowns About EtO

There are still many unanswered questions regarding EtO, and the risk of exposure to low levels of EtO is not well understood. The USEPA is working to find answers to questions such as:

  • Why is EtO found in areas with no known sources and what are those sources?

  • How do the ambient levels of EtO vary nationally and seasonally across the country?

  • How long does EtO persist in the atmosphere?

  • What is its involvement of atmospheric chemistry and transport?

  • What are the best methods for measuring EtO in real-time and/or at the source?

  • How can methods used to monitor for EtO be improved?

  • What are the next steps if the presence of EtO is confirmed to be everywhere?

While the USEPA and State air agencies are working together to better understand emissions in areas identified by the 2014 NATA, national air quality data shows that total emissions of air toxics are declining, and the concentrations of many air toxics are trending downward.

For the latest information from the USEPA, please visit EPA’s Actions on Ethylene Oxide webpage.

Further Reading

Additional Links and Related Information

Contact Us

West Virginia Department of Environmental Protection
Division of Air Quality
601 57th Street SE
Charleston, WV 25304
Phone: (304) 926-0475