Our Current Understanding of Ethylene Oxide (EtO)

Ethylene Oxide (EtO) is a Colorless Gas

Ethylene oxide (EtO) is produced in large volumes at some chemical manufacturing facilities. In the U.S., this colorless gas is primarily used to make other chemicals that are used to make a range of products, including antifreeze, textiles, plastics, detergents, and adhesives. It is also used to sterilize devices that can’t be sterilized using steam or radiation, such as some medical and dental equipment. According to the Food and Drug Administration, approximately 50 percent of sterile medical devices are treated with EtO – about 20 billion each year. EtO is also used to sterilize some food products such as spices, certain dried herbs, dried vegetables, sesame seeds and walnuts.

EtO Primarily Enters the Environment in Air

When EtO is produced or used, some of it may be released to the air and water. Release to the air is the primary way it enters the environment. Due to EtO's physical and chemical properties, exposure through water is not expected. Additionally, EtO is not expected to be readily absorbed by sediment or soil.

Breathing Air Containing EtO is the Main Way People are Exposed

Workers may be exposed to EtO if they work in places where EtO is produced or used, such as chemical plants and commercial or hospital sterilizers. These workers potentially have higher-than-average exposure.
People who live near facilities that release EtO to the outdoor air may be exposed to EtO, depending on how much EtO is released and how close they live to the facility, among other factors.
It is unlikely that EtO would remain in or on food or remain dissolved in water long enough to be eaten or swallowed.
There also is limited information on levels of EtO at hazardous waste sites - in air, water, or soil. This makes it difficult to determine how likely it is that someone might be exposed to EtO at or near these sites.

EtO in the Air Near Facilities is Unlikely to Cause Immediate Health Effects

Based on available data, EPA does not expect EtO levels in the outdoor air around facilities that release it to be high enough to cause immediate health effects (these are known as "acute” effects). Short-term inhalation exposure to high amounts of EtO can cause headache, dizziness, nausea, fatigue, respiratory irritation (such as coughing, shortness of breath, wheezing) and, in some cases, vomiting and other types of gastrointestinal distress.

Long-term Exposure to EtO may Lead to Harmful Health Effects

EtO is a human carcinogen. It causes cancer in humans. Scientific evidence in humans indicates that regular exposure to EtO over many years increases the risk of cancers of the white blood cells, including non-Hodgkin lymphoma, myeloma, and lymphocytic leukemia. Studies also show that long-term exposure to EtO increases the risk of breast cancer in women.

Workers who use EtO as a part of their jobs and people who work, live, or go to school or daycare near facilities that use EtO may breathe in EtO at levels that can increase cancer risk. This risk is not the same for everyone and depends on how long a person is exposed over the course of their lifetime or career, as well as how much EtO is actually in the air. The distance from a facility or other EtO source plays a big role in how much EtO might be in the air.

The greatest risk is for people who work for their entire careers at facilities directly handling EtO with minimal worker protections in place.

Children May be More Susceptible to the Health Effects of EtO Exposure

Because children’s bodies are growing, they are expected to be more susceptible to the toxic effects caused by EtO. This is because EtO is mutagenic, meaning it can damage DNA. As children grow, they tend to be more susceptible to the harmful effects caused by chemicals, including chemicals that are mutagenic. For anyone, including children, risks would decrease with decreased exposure.

EtO May Pose Ecological Risks to Land Animals

Land animals that live near facilities that release EtO to the outdoor air may be exposed to and affected by EtO. EPA intends to conduct further evaluation to determine whether EtO may affect federal threatened or endangered species or their habitat.