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Hazardous Air Pollutants: Ethylene Oxide
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Our Current Understanding of the Human Health and Environmental Risks of Ethylene Oxide

Ethylene oxide (EtO) is a gas

Ethylene oxide (EtO) is produced in large volumes at some chemical manufacturing facilities. In the U.S., this 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% 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 is colorless and flammable

EtO is a flammable and colorless gas at room temperature. It dissolves in water and alcohol. EtO released into the air will break down within several months.

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. When it is released to water, some of it may move from the water into the air. EtO that stays in water will either break down or be destroyed by bacteria. The time frame for the breakdown of EtO can vary depending on environmental conditions.

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.  
  • It is unlikely that EtO would remain in or on food or remain dissolved in water long enough to be eaten or swallowed. There is limited evidence about whether EtO is commonly found in water.
  • 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 exposure to EtO for 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.

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. The greatest cancer risk is for people who have lived near a facility releasing EtO into the air for their entire lifetime.

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.  However, EtO has not been reported to bioaccumulate (increase over time) in organisms that live on land or in water.  

EtO dissolves in water, and it can move from water to the air. There is currently limited evidence that EtO is commonly found in water. Any release of EtO into water appears to be mostly from industrial sources.

There is insufficient information on the movement of EtO in soil. There is also a lack of information on what happens to EtO in sediment. Because of its physical and chemical properties, EtO is not expected to be readily absorbed by sediment or soil.

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Last updated on December 15, 2021