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EPA in Illinois

Sterigenics Willowbrook Facility - Background Information

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What is Ethylene Oxide (EtO)?

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

The Clean Air Act lists EtO as a Hazardous Air Pollutant. U.S. EPA recently updated its risk value for ethylene oxide and is working with industry, and state, local and tribal air agencies to address this chemical.

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About the facility

Sterigenics is a commercial sterilizer that uses EtO to sterilize medical equipment and other products. It has been operating in Building 1 (7775 Quincy Street) since 1984 and in Building II (830 Midway) since 1999. It is owned by Sterigenics International LLC, which operates nine EtO sterilization facilities in the United States. The facility currently operates under a Clean Air Act permit issued by Illinois EPA in 2015.

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Why EPA is involved

EPA is addressing ethylene oxide at the Willowbrook facility based on the results of the latest National Air Toxics Assessment (NATA). 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 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.

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. 

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