Blood tests show environmental exposure to ethylene oxide

Brenda Goodman is a senior news writer for WebMD. Andy Miller is editor and CEO of Georgia Health News.

Story updated

Illinois residents living about a half mile away from a medical sterilization facility have levels of the cancer-causing gas ethylene oxide in their blood that are about 50% higher than those who live farther away, according to newly released test results.

The testing was limited, involving blood samples from just 93 people who responded to fliers and social media posts about the project. Participants were not randomly selected, which may have introduced bias. The results have not been published in a peer-reviewed medical journal.

Lake County

Even so, the testing offers the first biological evidence that living near a facility that emits ethylene oxide increases a person’s body burden of the chemical, which has been linked to breast and blood cancers.

Researchers say their results suggest that a government entity should fund a second round of more carefully controlled sampling to fully characterize the threat to residents living near the plants.

The CDC paid for the screening, which was conducted by environmental health researchers at the University of Illinois at Chicago. The CDC also analyzed the blood samples.

The results will be used in health reports for area residents that are currently being compiled by ATSDR, the Agency for Toxic Substances and Disease Registry, a specialized division of the CDC that analyzes risks to communities from environmental exposures. ATSDR is currently investigating health risks from ethylene oxide exposure in other communities, including the metro Atlanta town of Covington, where a medical sterilizing plant operates and uses the gas.

Susan Buchanan, MD, associate director of the Occupational and Environmental Medicine program at the University of Illinois at Chicago, says the results surprised her. Buchanan, who led the project, says the test results have strengthened her belief that facilities that emit ethylene oxide are a health hazard to the communities that surround them.

“This is a class 1, known carcinogen. It should not be emitted anywhere near where people are living,” she said.

Chris Nidel, a Washington, D.C.-based attorney who practices environmental health law, says the testing is significant.

“This is what public health should be doing. It’s great that they’re doing it,” says Nidel.

“These studies are kind of few and far between, especially with respect to a live source like this,” he says.

“This is interesting in the sense that it points a finger at an industry and that it raises an alarm about cancer risk in the surrounding community, both of which rarely happen,” says Nidel, who is not currently representing any clients who believe they’ve been exposed to ethylene oxide.

“This shows that people are being poisoned in Illinois by these facilities,” he says.

In August 2018, the Environmental Protection Agency released a report that projected increased cancer risks to people in roughly two dozen communities around the U.S. Most of that risk was driven by exposure to ethylene oxide, also known as EtO, a chemical that is used to sterilize medical equipment but is also a building block of products like antifreeze and detergent.

The EPA report has led to community outrage in Illinois, Georgia and Michigan, with sterilizing plants closing and government action aiming to curb emissions.

The Sterigenics plant in Smyrna, which uses ethylene oxide, has been closed for weeks.

People who participated in the blood testing pilot project live in Lake County, IL, in the northern suburbs of Chicago. Lake County has four census tracts where EPA modeling suggests that cancer risks rise above 100 for every million people exposed over the course of their lifetimes.

The area has two facilities that release ethylene oxide — Vantage Specialty Chemicals and Medline Industries. Vantage uses ethylene oxide to manufacture household and industrial products. Medline packages surgical kits, then uses ethylene oxide gas to sterilize them. A cluster of people who had their blood drawn came from a neighborhood that sits about .56 miles away from Medline. Others were scattered throughout the area and some lived farther away.

In August, when researchers first advertised the project, they looked for residents who lived within three-quarters of a mile of either facility for at least four months.


Researchers soon realized, however, that they weren’t going to get enough participants with such restrictive limits — the CDC had asked them to try to recruit 100 participants — so they expanded the project to people who lived farther away.

Because wind disperses and dilutes the gas, air testing and air modeling have shown that ethylene oxide levels drop the farther one goes from a known source.  At the time, air testing results for the area had been uneven, with sporadic spikes and many samples showing that the chemical couldn’t be detected in outdoor air.

Researchers thought the all-comers approach would limit their ability to see any meaningful patterns.

“I’m just afraid there may not be dramatic differences between these folks, we’ll see,” said Buchanan in an August interview with WebMD.

When the results came back a few weeks ago, she was surprised because they showed average differences between residents who lived closer to Medline — within .56 miles of the facility — and those who lived farther away that were statistically significant. There were no similar correlations with proximity to the Vantage facility.

Medline spokesman Jesse Greenberg said in a statement:

“Since a full report has not been made available for review, Medline is unable to comment on this pilot study. However, we do share the opinion that additional examination of EtO surrounding our Waukegan, IL, facility [in Lake County] should be done. It should be noted that recent ambient air tests released by the Lake County Health Department show EtO levels at sites closest to Medline in Waukegan are below background levels the EPA measured in 34 different cities. Also, Medline regularly administers blood tests for Waukegan employees and has never found elevated EtO levels in 25 years.”

The tests measured something called a hemoglobin adduct. Hemoglobin is the oxygen-carrying protein in blood cells. Ethylene oxide glues itself to an amino acid that’s a building block of this protein — and it will stay there for the life of the blood cell — about 126 days. So tests for hemoglobin adducts measure approximately the last four months of a person’s exposure to the chemical.

Peter Boogaard, an industrial toxicologist and professor of environmental health in The Hague, Netherlands, has studied hemoglobin adducts in workers exposed to ethylene oxide. He  says they are an important biomarker for exposure.  His studies have shown that hemoglobin adduct levels correlate with changes to DNA.

But when told that researchers were attempting to measure them in communities exposed to industrial emissions, he was skeptical that they would be able to see meaningful differences.

“Unless it’s sky high, meaning you would had very significant exposure, it would be very difficult to determine if you’ve been exposed,” says Boogaard, who was interviewed before the study results were released. He says that’s because scientists think that our bodies make some ethylene oxide during digestion of food, and there appears to be a measurable background level of the chemical in air, even in locations away from known sources.

Boogard, like some other scientists who have studied the chemical, said he believes the emissions from these facilities aren’t large enough to cause harm. (He says that ethylene oxide can damage DNA, but our bodies have repair mechanisms in place to fix that damage before it causes trouble — like cancer.)

Buchanan acknowledged that measuring hemoglobin adducts in people exposed to the relatively lower levels of the gas that had escaped into outdoor air was an open question.

“We don’t know because it’s never been done before. That’s exactly why CDC paid for this to be done. Nobody has measured levels residents from levels nearing near a facility,” she said.

For participants who lived in a neighborhood approximately one mile from Medline, the average level of blood for ethylene oxide hemoglobin adducts was 50.1 pmol/gmHb, which stands for picomoles per gram of hemoglobin.

For participants who lived farther away, the average ethylene oxide hemoglobin adduct level was 29.8 pmol/gmHb. Those study participants were considered to have background levels for comparison.

Buchanan says she feels confident calling that number a background level, because previous studies have shown background levels at around 26 pmol/gmHb.

The lowest level in the study was 15 pmol/gmHb. The highest was 333 pmol/gmHb, in a smoker. Results from this and other smokers were excluded from the study because their levels were 5 to 6 times higher because of their exposure to tobacco.

Researchers didn’t just take people’s word for their smoking history. They excluded anyone who tested positive for the nicotine metabolite cotinine.

Buchanan mailed the test results to participants last week. The testing caused a stir on social media as people compared their levels and posed questions about what they might mean. Researchers for now aren’t sure what level of exposure is considered harmful. The UIC research team is planning to take questions at a community meeting on Jan. 12 at 2 p.m.

Tea Tanaka, one of the founders of the grassroots community group Stop EtO in Lake County, said her own level came back on the high end of the spectrum — 58.2. She lives about 4 miles from both facilities, but she works 2 miles south of Medline, generally downwind of the plant. She thinks most of her exposure happens at work. Her husband, who works from home, had average levels — 26.

She says the results made her “feel ill with worry.”

She said she and her husband have discussed moving. They’re worried that they will lose thousands of dollars on their house, since property values have crashed in the area. Now she’s worried that she may have to change jobs to get away from ethylene oxide, too.

“It’s sickening,” she says.

Editor’s note: After this story was published, researchers at the University of Illinois at Chicago informed us that they had discovered an error in their results.  Average levels of ethylene oxide hemoglobin adducts in blood were elevated in people who lived .56 miles from the Medline sterilization facility, not 1.2 miles, as was originally stated.  We have revised the story to reflect this new information.