Ethylene oxide: What is it?

Ethylene oxide (EtO) is a flammable, colorless gas that is commonly used to make products such as ethylene glycol (antifreeze), polyester and other textiles, pesticides, detergents, polyurethane foam, solvents, and other products. It is also used to sterilize pre-packaged medical equipment because of its ability to permeate plastic and cardboard packaging. Syringes, catheters, IVs, and other single-use medical devices that can’t withstand other forms of sterilization can be effectively disinfected with ethylene oxide.


The DNA-damaging properties of ethylene oxide have been studied since the 1940s. For decades the chemical compound has been recognized as one of the 33 most hazardous air pollutants identified by the Environmental Protection Agency (EPA) as posing the greatest human health risk in the largest number of urban areas.

Although U.S. health officials have long known about ethylene oxide’s adverse effects on human health, including cancer, it wasn’t until the EPA concluded an exhaustive 10-year study in 2016 that public health officials realized how extremely toxic the chemical is.

In the Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide report, EPA researchers determined that ethylene oxide is 30 times more likely to cause certain types of cancer in humans, especially lymphoma and leukemia, than previously understood.

Ethylene oxide has also been linked to abnormally high rates of pancreatic, stomach, and breast cancers in communities and industries with high risk of exposure.

Neurological disorders; eye, nose, and throat irritation; miscarriage and other reproductive problems; birth defects, and difficulty breathing are other adverse health effects connected to ethylene oxide exposure.


In 2018, several months after it reevaluated ethylene oxide’s toxicity profile, the EPA issued the results of its National Air Toxins Assessment (NATA) study, an evaluation of the health risks posed by airborne releases of toxins. The report flagged 109 census tracts where residents live under an elevated threat of cancer and other health problems posed by exposure to airborne toxins. According to that report, most of the risks were driven by a single chemical: ethylene oxide.

The 12 census tracts where people are living under the highest threat of health risks are all in Louisiana’s “Cancer Alley,” and all are in the shadow of facilities that produce ethylene oxide or use it to make other chemicals.

Census tracts in several other states, including Georgia, are also included on the EPA’s list of air pollution hotspots due to ethylene oxide emissions.

Despite the government’s knowledge of ethylene oxide dangers, communities exposed to EtO emissions are only now just learning about this incredibly dangerous form of air pollution, even after being exposed for several years and in some cases, several decades.

Georgia communities at risk

In July, WebMD and Georgia Health News published stories that detailed how communities in three of the census tracts in Georgia are at a significantly higher risk of cancer because of toxic emissions from two nearby medical sterilization plants: the Sterigenics sterilization plant in Atlanta, near the city of Smyrna, and BD Bard, a medical device manufacturer in Covington, a few miles east of Atlanta.

Despite these alarming findings, the EPA decided not to warn the general public about the ethylene oxide risks in Georgia and several other states, and state environmental regulators chose not to warn citizens either.

In Georgia, state regulators seemed to be especially intent on protecting polluters from potentially damaging evidence linking their emissions to cancer deaths. Georgia’s Environmental Protection Division (EPD) had no plans to boost ethylene oxide emissions testing in and around the sterilizing plants and the communities near them, nor did they plan to engage the public about the problem, require better pollution controls, or boost oversight until media reports generated public outcry.

On the federal level, industries that use ethylene oxide are taking advantage of the Trump administration’s anti-regulatory environment to actually push for looser emissions laws, regardless of the EPA’s relatively new understanding of the chemical’s toxicity.

“The controversy pits companies that make and use ethylene oxide … against the EPA’s scientists and epidemiologists charged with protecting the public’s health. And it unfolds at a time when the Trump administration has been relaxing environmental regulations,” the Atlanta Journal-Constitution reported.


SterigenicsThe Sterigenics plant in the northwestern corner of Atlanta near Smyrna, Georgia, is one of 47 similar facilities in 13 countries. The plant sterilizes more than a million pieces of medical equipment every day and operates around the clock, seven days a week, with around 30 employees.

According to company data, which both federal and state regulators depend on for their research, the Atlanta Sterigenics plant has released about 8,500 pounds of ethylene oxide per year on average.

Two of the EPA census tracts under an elevated threat of ethylene emissions lie in the shadow of the Sterigenics sterilization plant. The agency determines that the cancer risk posed by airborne toxins is acceptable if it is lower than 100 cases per one million, or one in 10,000. In the Georgia census tracts with the greatest air pollution risks, the National Air Toxics Assessment (NATA) levels were far higher.

By the EPA’s estimations, 80 percent of the extra 114 cases of cancer per 1 million people are attributable to ethylene oxide.

Residents in the Chicago-area community of Willowbrook, Illinois, successfully pushed the government to shutter a Sterigenics sterilizing facility after learning that the cancer risk it posed to nearby residents was hundreds of times the acceptable EPA limit. The plant is trying to re-open with the government’s permission to release 85 pounds of ethylene oxide annually.

Likewise, residents living near the Sterigenics plant in Atlanta are pushing legislators for action. In response to public outcry, Sterigenics is currently working to install additional emissions-curbing controls in its Atlanta facility. The proposed measures would bring the ethylene oxide releases down to about 40 pounds a year – a level that the company publicly has stated is “near zero.” However, based on the EPA’s recent health assessments, there truly is no safe level of ethylene oxide for humans.

BD Bard

The BD Bard plant in Covington, Georgia, has been making sterile medical equipment for decades.

EPA records show the plant has been releasing ethylene oxide into the outdoor air since at least 1987, the first year the federal government required companies to report toxic chemical emissions. According to WebMD, the BD Bard plant that year reported releasing more than 76,000 pounds of ethylene oxide. By 1991, the plant’s annual emissions were about half that much, but still incredibly high.

The people in the census tract affected by BD Bard’s emissions are exposed to ethylene oxide levels many times higher than the level state regulators deem safe. In the Covington Mill neighborhood, ethylene oxide emissions are 23 to 34 times higher than the “safe” level each year. Residents on the other side of the plant in the Settlers Grove community have been exposed to ethylene oxide 97 times above the maximum level the government considers reasonably safe.

One high-ranking EPA official told the Atlanta Journal-Constitution that ethylene oxide is more prevalent in the environment than previously known. When communities around the U.S. have tested for it, they often find it in areas they weren’t expecting to find it or in higher concentrations than had been predicted.

Ethylene oxide molecules released from plants such as BD Bard and Sterigenics eventually disperse in outdoor air, but they have a half-life of about seven months. That means EtO particles persist in the environment for 14 months before they completely break down.

Occupational exposures

The Occupational Safety and Health Administration (OSHA) has set a workplace exposure limit of 1 part per million (ppm) of ethylene oxide over an 8-hour workday, 40-hour workweek, and a short-term exposure limit of 5 ppm, not to exceed 15 minutes. Although employers are required to comply with safety regulations to protect employees from toxic exposure, the truth is that workers still can and do become exposed to ethylene oxide through safety lapses and accidental releases.

In addition to putting workers at risk of cancer and other serious illnesses, research has shown that ethylene oxide and other chemicals and pollutants in the workplace may compromise the lives and health of unborn children. A recent study published in the journal Occupational & Environmental Medicine indicates that exposure to gene-damaging chemicals in the workplace and environment could trigger the development of autism and other neurodevelopmental disorders in the unborn children of expectant mothers.

It’s not uncommon for companies to tout their workplace safety records, yet even those in compliance with federal and state regulations experience accidental releases of ethylene oxide triggered by equipment failures, improper procedures, and other causes.

On July 31, 2019, the Sterigenics plant near Smyrna, Georgia experienced an accidental leak of ethylene oxide caused by a faulty gas valve. The company didn’t disclose the accident to state regulators but circulated an email among employees saying that workers had evacuated the facility. That leak followed an explosion at the same plant in July 2018 that severely injured one worker, and a separate ethylene oxide leak in April 2018 that the company also failed to disclose to state regulators.

Ethylene Oxide Exposure Lawyers

Lawyers in Beasley Allen’s Toxic Torts section are examining issues surrounding ethylene oxide and increased risk of cancer. For more information about this topic, contact Rhon Jones, who is head of our Toxic Torts Section.

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