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Hazardous Air Pollutants: Ethylene Oxide

Background Information on Ethylene Oxide

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What is ethylene oxide?

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

Ethylene oxide in the air can come from different types of sources, including industries such as chemical manufacturers and sterilizers.

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Why EPA is involved

EPA is addressing ethylene oxide based on the results of the latest National Air Toxics Assessment (NATA), which identified the chemical as a potential concern in several areas across the country. NATA is the Agency’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 2014 NATA uses emissions data from the latest National Emissions Inventory (2014 is the most recent data available), along with the latest scientific information on air toxics and health, to estimate long-term air toxics exposures and potential public health risk in census tracts across the United States.

NATA estimates long-term risks – those that may occur from breathing air containing elevated levels of air toxics continuously for many decades. It does not estimate short-term (acute) or intermediate risks. However, based on an examination of available data, EPA does not expect ethylene oxide levels in the air in these areas to be high enough to cause immediate harm to health.

Nationwide, total emissions of air toxics are declining, and air quality monitoring data show that concentrations of many toxics in the air, such as benzene, also are trending downward.

Despite these trends, some local areas still face challenges. The 2014 NATA estimates that ethylene oxide significantly contributes to potential elevated cancer risks in some census tracts across the U.S. (less than 1 percent of the total number of tracts). These elevated risks are largely driven by an EPA risk value that was updated in late 2016.

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Health risks of ethylene oxide

Long-term exposure to ethylene oxide can irritate the eyes, skin, nose, throat, and lungs, and harm the brain and nervous system (causing effects such as headaches, memory loss, numbness). Studies show that breathing air containing elevated ethylene oxide levels over many years increases the risk of some types of cancers, including cancers of the white blood cells (such as non-Hodgkin lymphoma, myeloma and lymphocytic leukemia); and breast cancer in females.

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