Ethylene oxide and Terumo BCT

EPA hosted a virtual Lakewood community meeting on Sept. 22, 2022. EPA presented their 2022 ethylene oxide risk modeling analysis for the Terumo BCT Sterilization Services facility. This map outlines the area EPA estimates to have greater than 100 in a million estimated lifetime cancer risk from breathing air containing ethylene oxide from the facility. This estimate is 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.


In 2016, the U.S. Environmental Protection Agency looked at new information on a chemical called ethylene oxide and established a more protective health level for ethylene oxide in the air. Breathing in ethylene oxide at certain levels over decades may cause an increased risk of certain types of cancers, and it can cause other health impacts.
Based on the more protective level and information in the U.S. Environmental Protection Agency’s 2014 National Air Toxics Assessment, released in August 2018, Terumo BCT Sterilization Services, Inc., 11308 W. Collins Ave. in Lakewood, was identified for further study. The air toxics assessment identified a possible increased cancer risk around Terumo BCT, but was based on computer models, not actual exposures to ethylene oxide.
EPA's 2022 Air Toxics Screening Assessment (AirToxScreen), based on 2017 data, shows a similar cancer risk. The 2017 AirToxScreen data does not account for emissions controls the company put in place in 2018. EPA's more detailed assessment released in 2022 includes these emissions controls and shows an elevated cancer risk.  

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.
Terumo BCT is not violating any current air pollution control requirements and voluntarily installed additional controls at the sterilization facility in 2018 to reduce the amount of ethylene oxide released into the air. The more protective risk level and the 2018 air toxics assessment led to the need for additional study. 

Air monitoring and health impacts studies

The Colorado Department of Public Health and Environment monitored the air twice in the vicinity of Terumo BCT and also monitored the air at other locations in the west Denver metro area (background samples). We monitored first in August 2018 before Terumo BCT installed additional emissions controls, and then in October 2018 after the additional emissions controls were installed. Ethylene oxide levels were significantly lower after the additional controls were installed.
After the air monitoring was complete, we estimated potential cancer risks in the area surrounding Terumo based on current emissions. We also looked at actual reported cancer rates in the area.

What the health impacts study found

We found no evidence that there currently is more cancer in the communities around Terumo BCT than in surrounding areas. However, the predicted cancer risks in the community near Terumo BCT are above the EPA’s guidance for “acceptable” risk level (more than 100 excess cancers in one million exposed people). Breathing low levels of ethylene oxide similar to those detected in the neighborhood surrounding Terumo BCT over a lifetime may lead to a small increase in a person’s overall cancer risk. The levels of ethylene oxide in our air testing around Terumo BCT were well below levels expected to cause non-cancer health impacts.
The Colorado Department of Public Health and Environment’s air testing shows Terumo BCT’s installation of additional controls resulted in a two- to five-fold reduction in the cancer risk to residents in the area, and more generally, a significant reduction in ethylene oxide concentrations around the facility. Additionally, Terumo committed to installing additional controls to further reduce emissions from the facility by summer of 2023. We do not know how much these controls will reduce the cancer risks in the surrounding community. We will use measurements of the new controls’ efficiency to better understand these impacts.
Because certain cancers take a lifetime to develop, it could be decades before data would show whether the increased risk is associated with an actual increased rate of cancer. The exact chance of cancer to people exposed to ethylene oxide in the air around Terumo BCT cannot be known. Exposure depends on how long a person has lived there, wind and weather patterns, how much time is spent outdoors, an individual’s health, and other factors.

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.

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.


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.

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 headaches, 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.

Children are expected to be more susceptible to the 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, it means that someone exposed to ethylene oxide over many years (a lifetime of exposure) has a slightly increased risk of developing cancer as compared to someone not exposed to ethylene oxide. There are many other factors that can lead to cancer, including heredity and lifestyle choices. 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.

More about cancer risk 


There are many other factors that can lead to cancer, including heredity and lifestyle choices. In Colorado, 1 in 2 men and 2 in 5 women will be diagnosed with cancer in their lifetime. There are steps people can take to lower their overall cancer risk.

More about preventing cancer

The National Air Toxics Assessment (NATA) was a screening tool intended to help EPA and state, local and tribal air agencies determine if areas, pollutants, or types of pollution sources should be examined further to better understand potential risks to public health. NATA results are based on computer modeling.

In 2022, EPA replaced NATA with a similar screening tool, AirToxScreen.

More about AirToxScreen from EPA.

EPA is reviewing its current air regulations that limit the amount of ethylene oxide certain types of industries release into the outdoor air to determine whether legal standards for ethylene oxide emissions to air can be further strengthened. EPA also is working with state, local, and tribal air agency partners, and with companies, to identify opportunities to reduce emissions faster than national regulations can achieve.

More about EPA’s work on ethylene oxide

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. We recommend people don’t smoke or use tobacco and don’t drink too much alcohol. Limiting time in the sun, increasing exercise, maintaining a recommended body weight, eating a healthy diet, and getting screened for cancer also will reduce your risks.


  • 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 health care provider.
  • Community members in the area around Terumo BCT who want more information about exposure to ethylene oxide can call the state health department’s ToxCall line at 303-692-2606 or send an email to