Limited air testing near a closed medical sterilization plant in Cobb County found elevated levels of ethylene oxide, a carcinogenic gas that has caused public protests and town hall meetings around facilities that use the gas.
The readings in Cobb were more than 10 times above the threshold federal regulators say poses long-term elevated cancer risk.
The test results were, however, largely in line with higher-than-expected background levels of ethylene oxide found across the country, and probably did not represent emissions from Cobb's Sterigenics plant, experts said.
“I very much doubt that the values seen in these measurements are anything other than a background measurement,” Barry Ryan, an environmental exposure expert at Emory’s Rollins School of Public Health, wrote in an email. “[T]he concentrations noted near operating facilities tend to be higher than these values.”
Ryan’s conclusions were echoed by Kyle Steenland, an epidemiologist at Emory who authored an influential study linking ethylene oxide to cancer.
The readings from Cobb were significantly lower than those taken in Covington where a similar sterilization facility owned by Becton Dickinson is currently operating. Those readings prompted BD to enter into a consent order with the state imposing additional oversight.
Medical sterilizers, including Sterigenics and BD, have come under increased scrutiny since the federal government concluded ethylene oxide is much more dangerous than previously thought. The issue came to a boil over the summer after Georgia Health News and WebMD published a joint report highlighting potential increased cancer risks in areas surrounding the plants.
Sterigenics closed in August to install new pollution controls, after its ethylene oxide emissions sparked protests but before any air samples were collected. The facility has remained closed pending permit approvals from the county. It is unclear when it will reopen.
Some three dozen samples taken in Cobb by the state Environmental Protection Division between September and November averaged about .29 micrograms of ethylene oxide per cubic meter of air.
The federal Environmental Protection Agency says long-term exposure to anything higher than 0.02 micrograms per cubic meter presents an unacceptable health risk resulting in more than 100 cancer cases per million people.
EPD spokesman Kevin Chambers wrote in an email that while there is no way to know for certain, the agency believes that it is unlikely that the ethylene oxide readings from Cobb are heavily influenced by Sterigenics operations before it closed in August.
“Unfortunately, almost all ambient air quality monitoring conducted in Georgia and across the country has been above the US EPA risk level,” Chambers said. “These sites are all existing, long-term US EPA air monitoring locations in a wide variety of urban and rural settings and all far exceeded .02 US EPA risk level.”
Georgia’s ethylene oxide test results were recently revised after Eastern Research Group, the contractor that processed the samples, tweaked its methodology. Some values were revised upwards, others downwards. Most samples previously marked “non-detect” provided measurable ethylene oxide concentrations.
Richard Peltier, an expert in air pollution exposure at the University of Massachusetts, Amherst, said scientists are always trying to assess background concentrations of ethylene oxide, which are often on the border of detection limits.
“Even with improved detection limits, these [ethylene oxide] values are still well above what EPA considers safe for lifetime exposures,” he wrote of the Cobb monitoring results. “And it’s troubling that the main contractor, ERG, is monkeying with their analytical methods when this is such a profound problem.”
A spokesman for Sterigenics did not respond to a request for comment, but has said previously that detection levels of the gas in cities such as Chicago, Denver, and downtown Los Angeles have all been found to greatly exceed the level that EPA says is acceptable.
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