Sterigenics today cited information that vehicles in the area near its Willowbrook, Ill. medical device sterilization facility emit far greater amounts of ethylene oxide (EO) than the plant did before its abrupt shutdown in February.
The Willowbrook plant shutdown appears to have also sparked renewed controversy among EO advocates and two major environmental organizations about federal EO emission and exposure regulations.
Sterigenics maintains that recent construction and a diesel generator near its plant may have contributed to emissions of EO, which the Willowbrook plant used to sterilize thousands of medical devices daily. The Illinois EPA shut down the Sterigenics Willowbrook plant Feb. 15 based on a federal disease registry’s conclusion that residents and off-site workers in the area around the plant were at risk for a “30-fold increase in cancer potency.”
Sterigenics cited an independent analysis conducted in the Chicago area that found vehicles release approximately 52,000 pounds of EO in the area per year and account for about 6,800 pounds of EO emissions in DuPage County per year. The Sterigenics Willowbrook facility emitted approximately 380 pounds of EO per year when it was most recently operating, according to the company. The analysis, conducted by engineering consultant group Ramboll, was released May 8.
“As the U.S. EPA has already indicated, there are multiple sources of EO in the Willowbrook area. EO emissions from vehicles in DuPage County are approximately 18 times greater than the amount of EO released by the Willowbrook facility, clearly indicating that cars and trucks are a significant contributor to EO levels in the air around Willowbrook,” the statement said. “Our research also shows that, in addition to vehicles, recent construction and the operation of a diesel generator near our Willowbrook facility likely contribute to EO emissions measured by the U.S. EPA in its ambient air monitoring program.”
Sterigenics also highlighted the findings of two recent studies that examined the potential health risks of EO. A study published in the International Journal of Environmental Research and Public Health reevaluated the historical exposures to EO among sterilization workers in a National Institute of Occupational Safety and Health (NIOSH) study cohort. The U.S. EPA relied upon the NIOSH cohort study findings for a 2016 Information Risk Information Systems (IRIS) risk assessment. The review found that the trend in EO exposures during the study period was opposite the trend indicated in the NIOSH study, “suggesting that the US EPA’s exclusive reliance on the NIOSH cohort to estimate EO cancer risk should be re-examined.”
The second study was based upon a systematic literature review and meta-analysis of studies of cancer risks among workers exposed to EO and published in The International Archives of Occupational and Environmental Health. The researchers concluded that the most recent and informative studies on the topic “do not support the conclusion that exposure to EO during production or use in sterilization processes” is associated with an increased risk of lymphohematopoietic cancers or breast cancer.”
Trade and environmental groups have also weighed in since the Willowbrook plant shutdown.
The Ethylene Oxide Sterilization Association’s website says the EPA’s conclusions about the cancer risk posed by EO are overstated and therefore flawed. The association also says that the EPA did not take into consideration other sources of EO in the environment in reaching its conclusions. The American Chemistry Council’s ethylene oxide panel also claims that the EPA vastly overestimates the cancer risk from inhaled EO.
An April 26 letter submitted to the EPA by the National Resources Defense Council and Earthjustice asks that federal and state agencies, including the EPA, use and apply the 2016 EPA IRIS assessment of EO to evaluate health risks and “set health-protective regulations and emissions restrictions, instead of ignoring the best available science.”
The EPA says that the risk of developing cancer from EO exposure is based on:
- “Strong, but less than conclusive on its own,” epidemiological evidence of lymphohematopoietic cancers and breast cancer in workers exposed to EO.
- “Extensive evidence” of carcinogenicity in laboratory animals, including lymphohematopoietic cancers in rats and mice and mammary carcinomas in mice following inhalation exposure.
- “Clear evidence” that EO is genotoxic and sufficient weight of evidence to support a mutagenic mode of action for EO carcinogenicity.
- “Strong evidence” of chromosomal damage and other events in humans exposed to EO that precede tumor development.
“Establishing sound public policy to protect the citizens in our communities requires accurate information and reliable data,” said Sterigenics president Phillip Macnabb, in today’s company statement. “These recent studies examine important elements regarding the sources and potential health risks of EO and provide critical data that are essential in
establishing the best policy to keep the public safe. Sterigenics remains committed to working with regulators, legislators and Illinois public officials to evolve regulations and continuously improve our operations in the ongoing interest of public safety.”
Earlier this month, a federal judge dismissed a lawsuit that Broadview Heights, Ohio-based Sterigenics brought against the state of Illinois for ordering it to shut down the Willowbrook plant, saying the matter belongs in state court. Sterigenics filed a lawsuit in state court the same week.