Ethylene oxide — a substance used for sterilizing medical devices — is at the center of a dogfight over protecting public health while also preserving a supply chain, Jael and Axios Pro Health's Maya Goldman write.

Why it matters: A chemical helping to keep Americans alive may also be making people sick, creating a situation that's sent lawmakers scrambling and positioned federal officials against the industries they regulate.

Driving the news: The EPA in April proposed new commercial standards for ethylene oxide, or EtO, including new emissions restrictions for sterilization facilities and chemical plants.

• EPA's moves are based on risk assessments, including a 2016 report finding with "high" confidence that ethylene oxide is "carcinogenic to humans."
• Like PFAS, this odorless gas has become the subject of many civil claims and was at the center of a Trump-era dust-up over alleged suppression of science.

Between the lines: Stakeholders are facing an uncomfortable truth: This chemical's pretty hard to get rid of right now.

• EtO has numerous uses, but crucially helps sterilize half of all medical devices in the U.S. each year, according to an FDA spokesperson.
• AdvaMed, a medical device lobbying group, and other industry outfits say EPA's proposals would cause "critical shortages" of medical devices.

Threat level: Chemicals trade representatives in D.C. have aimed at EPA's science and a chemicals program known as IRIS, as well as broadcasting EtO's myriad uses, including in EV batteries.

• The American Chemistry Council is involved in an ongoing legal challenge to a 2020 rule on reducing EtO emissions from vents and storage tanks. Their effort questions the viability of the 2016 risk assessment's findings.

Yes, but: Darya Minovi, a senior analyst at the Union of Concerned Scientists, is optimistic that FDA can find alternative sterilization methods.

• "We should value the health of the people who live near these facilities a little bit more than our system has," Minovi told Jael.
• An FDA spokesperson, meanwhile, says that "while signs of innovation are promising, other methods of sterilization cannot currently replace the use of EtO for many devices."

The intrigue: The EtO fight has sparked visceral reactions from allies and foes in Congress.

• The fight against EtO has been led primarily by lawmakers from Illinois, home to a high-profile EtO exposure site.
• Rep. Brad Schneider created a bipartisan EtO task force in 2019 with former Rep. Jody Hice and recently wrote in support of EPA's proposed regulations with Sens. Tammy Duckworth and Dick Durbin.
• "This is not a binary choice between making sure we have medical devices, medical products and clean air. We're able to do both," Schneider told Maya.

What EPA says: Shayla Powell, an agency spokesperson, provided a statement saying EPA's goal is to reduce "cancer causing EtO exposure to workers and community members, while maintaining the integrity of the supply chain."

• "We are working with FDA and others on potential supply chain issues and will use the input gathered during the public comment process in making any final decision."

What we're watching: House appropriators included language in the Interior-Environment bill that would restrict EPA from using funds to create new standards for EtO emissions until FDA certifies that the action won't cause a medical device shortage.