What are sources of EO?

Ethylene oxide in the atmosphere can come from several different sources, including natural sources, everyday activities and commercial industries. 

  • Natural sources of EO can come from plants, microbes and ripening fruits. Additionally, ethylene oxide is internally produced by your body as part of its normal metabolic process. Published research on Internally Produced Equivalent EO values (Kirman and Hayes 2017) concluded that the mean normal internally produced level of EO for a non-smoker is 19,000 times greater than the risk level stated in EPA’s Integrated Risk Information System (IRIS) risk assessment.   

  • Everyday sources of EO can come from cigarette smoke or auto exhaust emissions.  According to the World Health Organization, a cigarette releases 1,100 times more EO than the lowest canister reading in the recently published ATSDR report. 

  • Commercial sources of EO can come from chemical manufacturers, hospitals and medical sterilization facilities near where people work or live.  In fact, there are more than a dozen medical facilities located in DuPage and Cook counties that use EO to sterilize medical products and also emit EO.

As a result, there is a general background of EO in the atmosphere from these sources.  The US EPA recognizes there are low levels of EO found in the environment and conducted a long-term background monitoring program between 1999 and 2010 in which EO was found at low levels in many samples. 

What should I know about internally produced ethylene oxide?

The human body produces ethylene oxide internally from ethylene, including when we break down fats, or when we breathe in ethylene from the air.  (Ethylene in the air comes from sources such as ripening fruit and other natural and artificial sources.)  A recent study estimated the level of ethylene oxide internally produced in people with no known exposure to inhaled ethylene oxide.  This study estimated that these people have levels of a blood “biomarker” approximately equivalent to air concentrations for ethylene oxide of 0.67 to 12.4 ug/m3.  As the chart below shows, the air concentrations reported in Willowbrook by EPA during the limited period in May 2018 reviewed by ATSDR/EPA are within this range.  Sterigenics has reduced its ethylene oxide emissions an additional 90% since the time these measurements were taken by EPA.

Willowbrook Air Concentrations of Ethylene Oxide Reported, Compared to Equivalent Exposure from Internally-Produced Ethylene Oxide

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Why is EO critical to the healthcare industry?

Ethylene oxide is used to sterilize over 50% of the medical devices and nearly 90% of the surgical kits used by the healthcare industry.  According to the Ethylene Oxide Sterilization Association (EOSA), EO is used to sterilize over 20 billion medical devices each year in the U.S. alone.  For the vast majority of single-use medical devices, complex implantable devices, surgical kits and multi-use devices that are reprocessed in a hospital setting, EO sterilization is the ONLY practical method of sterilization available.  These devices, tools and kits cannot withstand other sterilization methods as the efficacy of the products being sterilized would be compromised and the risk of infection would increase.  Hence, there is real-world need for reliable sterilization to meet the needs of patients for safe healthcare and infection prevention. 

The US EPA itself has concluded that EO is important to the medical device industry and hospitals and necessary to protect public health.  The agency concluded that while there are other sterilization methods for treating some medical devices, there is currently no available sterilization method that has been accepted as a practical replacement for EO for  important uses that include heat-sensitive and irradiation-sensitive devices or equipment.

The Sterigenics Willowbrook facility alone sterilizes products that have a broad impact on healthcare, including 1,500 surgical procedure kits, 11,000 radiological syringes and 16,000 vascular catheters each day.  These products support thousands of necessary healthcare procedures every day, in many cases without meaningful volumes of products in inventory should an outage in sterilization occur.  At this time, the only practical FDA-approved method for delivering this solution for many medical products is EO sterilization.  Any disruption of this process could result in unacceptable and life-threatening delays of necessary surgical procedures as the tools and devices necessary to accomplish these procedures would not be available.