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Hazardous Air Pollutants: Ethylene Oxide

Frequent Questions on Ethylene Oxide

Q. What is ethylene oxide and what are its uses?

A. Ethylene oxide (EtO) is a gas at room temperature.

There are two key uses for ethylene oxide: 1) It is used to make other chemicals that produce many everyday products and 2) It is used to sterilize devices that can’t be sterilized using steam, such as some medical and dental equipment.

Ethylene oxide is reacted to make ethylene glycol, which is a key ingredient in a variety of consumer household products. Ethylene oxide is an essential building block for synthetic fibers (e.g., upholstery, carpet), plastics, PVC pipe and cosmetics.

Q. Can ethylene oxide cause immediate/acute health effects?

A. Acute (short-term) inhalation exposure to high concentrations of EtO can cause headache, dizziness, nausea, fatigue, respiratory irritation (e.g., coughing, shortness of breath, wheezing) and, in some cases, vomiting and other types of gastrointestinal distress.

Q. When did EPA classify ethylene oxide as a carcinogen?

A. EPA classified ethylene oxide as a human carcinogen in December 2016. Studies of workers show that their exposures to ethylene oxide e are associated with an increased risk of cancers of the white blood cells (the infection-fighting cells of the immune system). Studies also showed an increased risk of breast cancer in females.

Q. Why have the ethylene oxide results in EPA’s National Air Toxics Assessment (NATA) changed in my area from the previous NATA?

A. Newer studies show that ethylene oxide is a more potent carcinogen than scientists had thought. We updated our cancer risk calculations to reflect these new data. This means that in the 2014 NATA, more areas show elevated risks driven by ethylene oxide than in the 2011 NATA. This does not mean there is more of this compound in the air in these places than before. Even if emissions in an area are the same—or possibly even if they are lower—the new cancer value often results in a higher risk estimate.

Q. What kinds of cancer does EtO cause?

A. Evidence in humans indicates that long-term exposure to ethylene oxide 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 ethylene oxide increases the risk of breast cancer in females.

Q. Are there medical tests to see if I have ethylene oxide in my system?

A. According to the Agency for Toxic Substances and Disease Registry (ATSDR) there are two kinds of tests that can determine if you have been recently exposed to ethylene oxide. One test measures ethylene oxide in blood and the other test measures it in your breath. However, these tests are not intended for use on individuals that may have been exposed to very low levels of EtO (as these tests are not sensitive enough to detect it) nor can they be used to predict how it will affect a person’s health. Because special equipment is needed, these tests are not usually done in the doctor's office.

Q. Are levels of ethylene oxide in my area high enough to cause immediate health effects?

A. Based on available data, we do not expect ethylene oxide levels in the air around facilities to be high enough to cause immediate health effects.

The short-term (one-hour) estimated levels in the air are well below levels that may immediately cause serious, long-lasting or irreversible noncancer health effects.

The mid-term estimated levels (two weeks to one year) and the long-term estimated levels in the air are also below levels that may cause noncancer health effects.

We will gather additional information from facilities that will help us better understand what the EtO levels are in the air.

Q. Are children at risk?

A. EPA is taking steps to reduce ethylene oxide in the air to reduce risk. The greatest risk is for people who have lived near a facility releasing EtO into the air for their entire lifetime. For a single year of exposure to ethylene oxide, the cancer risk is greater for children than for adults. This is because ethylene oxide can damage DNA. For everyone, including children, risks would decrease with decreased exposure.

Q. What is EPA doing to reduce ethylene oxide in my area and across the country?

A. We are taking a two-pronged approach to finding opportunities to reduce ethylene oxide emissions:

EPA is reviewing Clean Air Act regulations for facilities that emit ethylene oxide:

  • EPA has begun reviewing its air toxics emissions standards for miscellaneous organic chemical manufacturing facilities, some of which emit ethylene oxide.
  • The Agency also plans to take a closer look at its rules for other types of facilities, beginning with its emissions standards for commercial sterilizers. 

EPA is also getting additional information on ethylene oxide emissions

  • EPA also is gathering additional information on industrial emissions of ethylene oxide, which may include data from testing at facilities.
  • This information will help EPA as it looks for opportunities to reduce ethylene oxide emissions as part of its regulations review.
  • It also will help us determine whether more immediate emission reduction steps are necessary in any particular locations. We do not know yet whether those locations include the location you mentioned.