Dupage Policy Journal

Dupage Policy Journal

Wednesday, February 26, 2020

EPA estimates of risk from ethylene oxide greatly overblown, Texas environmental regulators say

By W.J. Kennedy | Sep 27, 2019


Texas officials have a much different take on the latent dangers of a chemical compound, ethylene oxide (EO), at the center of Willowbrook's Sterigenics dispute.

Texas environmental regulators have proposed regulations loosening restrictions of the emission of the gas, while some Illinois lawmakers have said they won’t be satisfied until the Sterigenics plant is permanently shut down. The plant uses EO to sterilize medical equipment.

Spokesman for the Texas Commission on Environmental Quality (TCEQ), Brian McGovern, told the DuPage Policy Journal that the U.S. EPA in determining risk value significantly over-predicted the number of cancers in a study of workers exposed to very high concentrations of EO over many years – levels millions of times higher than typical environmental concentrations of the compound. This, while the TCEQ, using a different model, accurately predicted the number of cancers in the worker study.


The difference, McGovern said in an email, was instead of using a standard straight-line risk model to predict the cancers the EPA chose to assume that low doses of ethylene oxide are more potent than high doses for causing cancer.

McGovern added that the human body naturally produces low levels of ethylene oxide. Higher levels are observed in those who smoke.

“Using the EPA’s risk assessment, the background levels of ethylene oxide in the population would be predicted to cause more lymphoid cancer than is actually observed in the general population (and ignoring any other potential cause of lymphoid cancer),” he said. “In this way, we also know that EPA’s model over-estimates the cancer potency of ethylene oxide.”

The EPA’s risk value is even far below levels found in nature, according to the American Chemistry Council (ACC).

“… It is 19,000 times lower than the normal, naturally-created levels of EO in the human body,” the ACC wrote in a September 2018 press release that announced it had filed a petition seeking an EPA correction to EO risk.

Media reports overstating the risk from EO levels near the Sterigenics plant led Democratic Gov. J.B. Pritzker to order its shutdown last February. Earlier this month, a DuPage County judge ruled that the plant could re-open. Before it does, the company must apply for permits to adhere to stricter emission standards.

“The judge’s resolves all current litigation between the State of Illinois and its representative agencies and Sterigenics, with no finding of liability or fault against either side and with no imposition of penalties,” Sterigenics said in a statement. “…The Court noted that the State has acknowledged that there is no uncertainty that Sterigenics has operated in compliance with federal standards regarding its ethylene oxide (EO) emissions."

Still, House Minority Leader Jim Durkin (R-Western Springs) is proposing legislation that would give municipalities the authority to ban the use of ethylene oxide in their communities. Pritzker has said he would call a special legislative session to consider such legislation.

Besides sterilizing medical equipment, EO is used to make plastics, adhesives, antifreeze, safety glass, textiles and other products. The EO production industry supports more than 45,000 jobs and provides approximately $3.5 billion in direct value to the U.S. economy, the Chemistry Council says.

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