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Hazardous Air Pollutants: Ethylene Oxide

Frequent Questions: Health Information About Ethylene Oxide


Health Information

Can ethylene oxide cause immediate/acute health effects?

Acute (short-term) inhalation exposure to high concentrations of ethylene oxide 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.

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When did EPA classify ethylene oxide as a carcinogen?

EPA classified ethylene oxide as a human carcinogen in December 2016. Studies of workers show that their exposures to ethylene oxide 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.

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What kinds of cancer does ethylene oxide cause?

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.

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

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.

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I asked my doctor about EtO and she said it is not linked to cancer in humans. But when I google, it’s listed as a carcinogen. Can you please explain?

EPA, as well as the International Agency for Research on Cancer and the National Toxicology Program, classifies ethylene oxide as carcinogenic to humans. Evidence in humans indicates that exposure to ethylene oxide by inhalation increases the risk of lymphohematopoietic cancers (including non-Hodgkin lymphoma, myeloma, and lymphocytic leukemia) and, for females, breast cancer.

 EtO is mutagenic (i.e., it can change the DNA in a cell). Children may be more susceptible to the harmful effects of mutagenic substances.

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Why has EPA intentionally withheld critical health information from the public about the cancer risks posed by EtO?

What we know about ethylene oxide has changed over time. EPA changed its health value for EtO in December 2016. The new health value is 60 times more toxic to children and 30 times more toxic to adults than the previous estimate. EPA incorporated the new health value in the most recent National Air Toxics Assessment (NATA), EPA’s nationwide air toxics screening tool, designed to help EPA and state, local and tribal air agencies identify areas, pollutants or types of sources for further examination.

The NATA takes about 3 years to produce. EPA gathers emissions of air toxics from all over the country, conducts an initial computer-based analyses to estimate risk, and then conducts a rigorous quality review of the inputs and results. EPA headquarters leads the effort and works with the EPA regions and the states to review the NATA and make changes to the initial draft. There are many changes that are made to that initial draft, including for EtO. This is a critically important part of the process, to be sure we are conducting the screening assessment with the best information possible. Only when we are certain that the NATA is correct do we release it. We released it in August 2018.

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I am pregnant and have small children, what are our risks?

As with any air pollutant, potential health effects associated with ethylene oxide (EtO) depend on amount inhaled and duration of exposure. Effects from short-term exposure to high levels of ethylene oxide in humans can include central nervous system depression and irritation of the eyes and mucous membranes. Chronic (long-term) exposure to EtO in humans can cause irritation of the eyes, skin, nose, throat, and lungs, and damage to the brain and nervous system. Some evidence (from historic occupational studies of workers at ethylene oxide facilities) indicates that exposure to high levels of EtO can cause an increased rate of miscarriages in female workers. We are not aware of data suggesting that EtO is associated with effects such as birth defects or autism.

EPA has established an inhalation cancer risk value for ethylene oxide, and California Environmental Protection Agency (CalEPA) has established a chronic noncancer health effect value for ethylene oxide.

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Besides being a cancer agent, is ethylene oxide known to cause skin conditions? breathing problems? or change a person’s DNA?

EPA, as well as the International Agency for Research on Cancer and the National Toxicology Program, classifies ethylene oxide as carcinogenic to humans. Evidence in humans indicates that exposure to ethylene oxide by inhalation increases the risk of lymphohematopoietic cancers (including non-Hodgkin lymphoma, myeloma, and lymphocytic leukemia) and, for females, breast cancer.

EtO is mutagenic (i.e., it can change the DNA in a cell). Children may be more susceptible to the harmful effects of mutagenic substances.

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How long does ethylene oxide remain in the body?

Ethylene oxide (EtO) is eliminated from the body fairly quickly – with levels dropping by about 50% every 42 minutes. (The elimination half-life of EtO in humans is approximately 42 minutes (Filser et al., 1992)). At that rate, almost 90% of ethylene oxide would be eliminated from the body in two hours.

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

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 (EtO). 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.

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Are children at risk?

EPA is taking steps to reduce ethylene oxide (EtO) 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.

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Is there information suggesting EtO causes birth defects, types of birth defects and Autism?

We are not aware of data suggesting that EtO is associated with effects such as birth defects or autism.

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Is ethylene oxide produced by the human body?

Yes, our bodies produce ethylene oxide when metabolizing ethylene, which is produced naturally in the body. ​The percentage of ethylene converted to ethylene oxide in the body is unknown, but expected to be low.

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Is my breast cancer caused by ethylene oxide?

There is no single cause of, or risk factor for, breast cancer. Studies show that long-term, occupational exposure to high levels of ethylene oxide increases the risk of breast cancer in women.  It is very difficult, however, to attribute specific instances of breast cancer to one risk factor.

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