Ethylene oxide and Terumo BCT


Since 2018, CDPHE and EPA have been working to reduce emissions and cancer risk in the communities surrounding Terumo BCT in Lakewood, CO. Terumo BCT uses ethylene oxide to sterilize medical equipment. Breathing in ethylene oxide at certain levels over many years can increase the risk of some types of cancer.



Based on new information about health risks, the U.S Environmental Protection Agency (EPA) established a more protective level for ethylene oxide in the air in 2016. In 2018, EPA identified the area around Terumo, BCT as having an increased cancer risk, based on emissions modeling. Terumo BCT installed additional emissions controls, and the Colorado Department of Public Health and Environment conducted air monitoring and health risk studies. In 2022, EPA conducted an additional analysis to model potential impacts to communities from sterilization facilities. EPA’s assessment also showed an elevated cancer risk.


Air monitoring and health risk studies in 2018

The department conducted a health risk study, which looked at cancer risk based on measurements of ethylene oxide in the community. The study also assessed the number of cancer cases in one census tract surrounding Terumo BCT to find out if they were higher than expected. The department found that levels of ethylene oxide in the community were significantly lower after Terumo installed new emissions controls. The new controls also resulted in a two to five times lower estimated cancer risk, but the risk was still above the EPA’s “acceptable” level of more than 100 excess cancers in one million exposed people. The department did not find evidence of more cancer cases in the area it analyzed. The levels of ethylene oxide were well below levels expected to cause non-cancer health impacts.

Ethylene Oxide Air Sampling Study

Community risk assessment of ethylene oxide near Terumo BCT in Lakewood, Colorado


Expanded analysis of cancer rates in 2023

The department conducted an additional study of cancer rates in 2023 and published a supplement to the 2018 health risk assessment. The study included three census tracts and data from 2000-2019. It found small increases in certain types of cancer that are linked to long-term ethylene oxide exposure. The study, conducted in response to community concerns, does not change the risk estimate, nor does it determine whether ethylene oxide caused or contributed to these cancers. This kind of study only establishes the cancer rate and whether it is above what is expected based on cancer rates across Colorado.

Supplemental Cancer Registry Evaluation in Areas Near Terumo BCT Lakewood, CO (2000-2019)


Future actions

All the studies conducted so far tell us we need to do more to lower the health risks from ethylene oxide in this community. Terumo committed to installing additional controls to further reduce emissions from the facility. The department will monitor air around the facility to understand how well the new controls are working. In addition, EPA has proposed new rules to lower ethylene oxide emissions, and the department supports these rules. Both of these actions should lower emissions and risk in communities around Terumo.

More about EPA’s work on ethylene oxide

Ethylene oxide is a chemical used to sterilize heat-sensitive medical equipment. Ethylene oxide also is used when making antifreeze, textiles, detergents and other products, and to disinfect spices and tobacco products.

Terumo BCT is a company that makes medical devices and has been operating in Lakewood since 2001. Like other companies that do this work, it uses ethylene oxide to sterilize medical devices made of plastics, polymers, metals and glass that cannot withstand the high heat and moisture of steam sterilization. Examples of such devices include catheters, resuscitation bags and anesthesia masks.

This facility was last inspected on March 16, 2021 and was determined to be in compliance with the emission limits in its permit. Terumo BCT voluntarily installed additional controls in 2018 to reduce the amount of ethylene oxide released into the air and said it plans to install more in 2024. 

Employees of facilities using ethylene oxide may be exposed to it in the workplace. People who live near a source of ethylene oxide, such as Terumo BCT, may breathe it in from the air. It is very difficult to measure ethylene oxide at low levels. This means we don’t know much about the actual levels in air far from known sources.

Cancer risk

The studies about ethylene oxide are about people who work with the chemical and who are exposed to it at much higher levels than are found in the air outside. Studies about workers exposed to ethylene oxide show an increased risk of blood cancers (Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, multiple myeloma and lymphocytic leukemia) and female breast cancer. Cancer risk for workers increased with higher exposure concentrations and more years of exposure time.

Non-cancer health impacts

Studies about workers exposed to ethylene oxide show breathing high levels of it over months or years (chronic/long-term exposure) may cause irritation of the eyes, skin, nose, mouth and throat. It also may affect the nervous system, leading to headache, nausea, vomiting, memory loss and numbness. Breathing it at even higher levels for shorter periods (acute/short-term exposure) may result in similar, but more severe impacts. There also is some evidence that higher exposures to ethylene oxide may increase the risk of miscarriage.

The levels of ethylene oxide measured around Terumo BCT were well below levels expected to cause non-cancer health impacts.

Children are more susceptible

Children are expected to be more susceptible to health effects of ethylene oxide. This is because ethylene oxide can damage DNA.

More about ethylene oxide from EPA.

More about ethylene oxide from CDC.

More about ethylene oxide for clinicians from ATSDR.

In this case, an elevated cancer risk means that someone exposed to ethylene oxide over many years has a slightly increased risk of developing cancer as compared to someone not exposed to ethylene oxide. There is some risk of cancer the EPA considers “acceptable.” Up to 100 additional cases of cancer in a million people is within the EPA’s “acceptable” range.

This map outlines the area EPA estimated in 2022 to have greater than 100 in a million estimated lifetime cancer risk from breathing air containing ethylene oxide from the Terumo BCT. This estimate was a worst-case scenario based on an individual breathing outdoor air 24 hours a day, 7 days a week, for 70 years.

Actual risk depends on how close people are, how much ethylene oxide they breathe, and how long they are in this area. These estimates cannot predict whether an individual person will develop cancer, but indicate an elevated risk based on the exposure outlined above.

More about cancer risk  

Cancer is not a single disease, but a group of more than 100 different diseases that share some characteristics. Cancer is common, it is the second leading cause of death in the United States. Each individual has a complex genetic makeup, health history, unique exposure history to chemicals, and other risk factors that interact and can lead to the development of cancer. While people can’t control all the factors in their environment, a healthy and active lifestyle, in addition to regular cancer screenings, can lower overall risk.

More about preventing cancer 



If you or your family are concerned about your health or have symptoms you think are caused by exposure to ethylene oxide, discuss these concerns with your healthcare provider.

Community members in the area around Terumo BCT who want more information about exposure to ethylene oxide can contact ToxCall at 303-692-2606 or cdphe_toxcall@state.co.us