Steris Lawsuit: Ethylene Oxide Claims and $48.15M Settlement

The Steris ethylene oxide lawsuit refers to roughly 275 personal-injury cases filed in Illinois state court alleging that emissions from a Waukegan, Illinois sterilization plant operated by Steris’s subsidiary Isomedix Operations caused nearby residents and workers to develop cancer. On March 3, 2025, Steris disclosed in an 8-K filing that Isomedix had agreed to pay up to $48.15 million to resolve its portion of the litigation.¹

What the Lawsuits Alleged

Plaintiffs lived or worked near a sterilization facility in Waukegan, in Lake County, Illinois. The plant used ethylene oxide, a colorless flammable gas used to sterilize medical devices. The EPA has linked chronic exposure to ethylene oxide with elevated risks of lymphoma, leukemia, multiple myeloma, and breast cancer, and the cancers named in the complaints span those diseases along with brain cancer and others.²

By late 2024, approximately 275 people had sued Steris in Illinois state court over the Waukegan emissions. They sought compensatory damages and, where allowed, punitive damages.³⁴

Why Steris Was the Defendant

The Waukegan plant has had several owners. Cosmed Group ran it from roughly 1993 to 2005. Steris, which had acquired the Isomedix brand in 1997, operated the facility from January 2005 through September 2008. Medline Industries owns it today.¹ The cases against Steris are tied specifically to the 2005–2008 window when Isomedix Operations controlled the plant. Each of the other owners has faced its own litigation. Cosmed filed for bankruptcy after more than 300 suits.⁵

Steris disputed the allegations. In its SEC disclosure, the company said “a loss is reasonably possible” but that a specific range could not be estimated given the fact-specific nature of each case, and that it was “vigorously defending itself” while pursuing contribution and indemnity from other parties. Management said it did not believe the litigation would have a “material adverse effect” on the company’s consolidated financial position, while conceding that insurance coverage offered “no assurance” of adequacy.⁴

The Trial That Pushed the Case to Settle

The first case to reach a jury was Pamela Knobbe v. Isomedix Operations, Inc. (No. 2022-L-008574), in the Circuit Court of Cook County. Trial began on December 4, 2024.⁶ During deliberations in January 2025, one juror walked out, dropping the panel below the required twelve. Knobbe declined to waive her right to a full jury, and the court declared a mistrial on January 17, 2025. Rather than retry the case, the parties resolved it, and a broader settlement followed weeks later.⁷

What the $48.15 Million Settlement Covers

The March 2025 agreement resolves approximately 275 lawsuits.⁸ Isomedix signed confidential term sheets with plaintiffs’ attorneys and individual settlement agreements with several plaintiffs whose cases were closest to trial. Confidentiality provisions prevent disclosure of how the money is divided among plaintiffs.¹

The number is a ceiling, not a guaranteed payout. Isomedix retains the right to keep defending itself against any individual plaintiff who does not sign the agreement, or if the court declines to accept the deal. The settlement also covers only Steris’s portion of the multi-party Waukegan litigation, and other corporate defendants remain in the cases.¹

Steris Is Not Sterigenics

The names get confused often enough to note. Steris plc, through Isomedix Operations, ran the Waukegan plant in Lake County. Sterigenics is a subsidiary of Sotera Health and operated a separate sterilization facility in Willowbrook, in DuPage County.⁴ Both companies face ethylene oxide litigation, but the cases involve different plants, different plaintiffs, and different corporate defendants.

Sterigenics’ exposure has been much larger. A Cook County jury awarded $363 million to a single plaintiff, Susan Kamuda, in September 2022, and in January 2023 Sterigenics and Sotera Health agreed to pay $408 million to settle over 870 Willowbrook-area cases while denying liability.⁹¹⁰ Those verdicts drew industry attention to the Steris cases, since they suggested juries could be receptive to EtO cancer claims.⁴

Regulatory Context

The claims sit against a shifting emissions rulebook. In April 2024, the EPA finalized a rule requiring commercial sterilizers to cut ethylene oxide emissions by 92 percent. In March 2026, the EPA under the Trump administration proposed rescinding those tighter standards, arguing the prior administration had exceeded its authority under the Clean Air Act. The proposal would also relax technology-based limits for larger facilities and drop requirements for continuous emissions monitoring.¹¹

Illinois moved earlier and further. The Matt Haller Act, signed by Governor JB Pritzker in June 2019, requires EtO-emitting facilities to capture 100 percent of emissions and reduce atmospheric releases by at least 99.9 percent, with mandatory annual testing and immediate shutdown if limits are breached.¹²

What Is Still Open

With the March 2025 deal, Steris has largely stepped out of the Waukegan litigation. It still retains the right to defend against any plaintiff who does not accept the settlement. Plaintiffs’ firms are also investigating potential claims tied to other Steris facilities, including a long-running plant in Northborough, Massachusetts, which has used ethylene oxide since roughly 1993 and is subject to the 2024 federal emissions-reduction rule.¹³ If you lived or worked near a Steris or Isomedix sterilization facility and later developed one of the cancers linked to ethylene oxide, whether your claim falls inside or outside the resolved Waukegan cases depends on the facility, the years of exposure, and whether you are among the plaintiffs already covered by the settlement.

1
Chicago Tribune. Waukegan Area Residents Sharing $48.1 Million Settlement for EtO Emissions From an Industrial Plant
2
Johnson & Bell. Medline Industries Ethylene Oxide Litigation
3
ICLG. Steris Faces Legal Storm Over Cancer-Causing Emissions
4
Medical Design and Outsourcing. Steris Ethylene Oxide EtO Lawsuits Isomedix Waukegan Illinois
5
Etzler Law Head Legal Group. Legal and Regulatory Actions Against EtO Exposure
6
Steris plc. Steris Announces Outcome of Ethylene Oxide Trial
7
Jones Day. Isomedix Favorably Resolves Ethylene Oxide Litigation
8
Cities 92.9. Companies Hit With Hundreds of Lake County EtO Lawsuits Cry Foul
9
MD+DI Online. Sterigenics Settles With 879 EtO Claimants for $408 Million
10
U.S. Securities and Exchange Commission. Sterigenics Settlement Announcement
11
Harvard Law School Environmental & Energy Law Program. Ethylene Oxide Emissions Standards for Commercial Sterilizers
12
Illinois Attorney General. Consent Order With Sterigenics Over Air Pollution Violations
13
Marin Murphy Law. Northborough MA EtO Exposure Lawsuits