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US EPA to reexamine ethylene oxide risks

Move could impact crackdown on chemical plant emissions

by Cheryl Hogue
June 22, 2021 | A version of this story appeared in Volume 99, Issue 24

Drawing shows 3-dimensional chemical structure of ethylene oxide.
Credit: Shutterstock

In an action sought by both the chemical industry and environmental advocates, the US Environmental Protection Agency will reexamine its 2020 regulation of ethylene oxide.

The EPA will ask the public for more input on the potency of the carcinogenic gas, the agency told C&EN in a June 22 email. This toxicity value guides the EPA in deciding whether to continue, relax, or strengthen regulation of ethylene oxide leaks from chemical plant equipment, vents, and storage tanks to protect the health of nearby communities.

Made from natural gas or petroleum, ethylene oxide is a basic starting material for manufacturing a variety of products, such as plastics and medicines. The gas is also used to sterilize medical equipment.

In a 2020 Clean Air Act rule, the Trump EPA required manufacturers of organic chemicals to curb their ethylene oxide emissions collectively by 0.69 metric tons per year. Environmental advocates decried the rule as leaving some fenceline communities near chemical plants with increased cancer risk as high as 200 in 1 million from breathing ethylene oxide. The agency’s rules generally limit increased cancer risk from exposure to pollutants to 100 in 1 million.

Meanwhile, the US chemical industry criticized the rule for relying on the EPA’s 2016 assessment of ethylene oxide. The sector’s main lobbying arm, the American Chemistry Council (ACC), calls that assessment flawed.

The ACC also faults the agency for failing to consider an analysis by the Texas Commission on Environmental Quality (TCEQ), which concluded last year that ethylene oxide is far less hazardous than the EPA determined. The TCEQ assessment was not peer reviewed in time for the EPA to consider it for the rule, the agency said in 2020.

Adoption of the TCEQ approach could allow for construction of new plants or expansion of existing facilities that make or use ethylene oxide, the Sierra Club has said.

A number of plants in Texas have high levels of ethylene oxide emissions—including the US facility that reported the highest releases of the chemical in 2019, Huntsman Petrochemical of Port Neches, according to the most recent data in the EPA’s Toxics Release Inventory.

Huntsman Petrochemical, the ACC, the TCEQ, the Sierra Club, and other advocacy groups petitioned the EPA to reconsider the rule.

“We appreciate the EPA’s willingness to consider the latest science on this issue.” the ACC says in a statement

“EPA must substantially strengthen these chemical plant rules by following the science to protect public health from cancer and other illnesses,” says Emma Cheuse, attorney for Earthjustice, the law firm representing the environmental groups seeking reconsideration of the rule.



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