“Due to a failure of a system, the Atlanta facility had an uncontrolled incursion of EO into a chamber that created an unsafe environment to operate,” said the email from Sterigenics general manager Daryl Mosby to one of the company’s clients.

“The event required a facility evacuation and shut down,” the email said. “While the event did not directly affect your product, per our safety procedures, the facility suspended processing while a safety investigation was completed.”

Sterigenics President Philip Macnabb talks to a packed house at Campbell Middle School during a July community meeting to address concerns over ethylene oxide emissions. STEVE SCHAEFER / SPECIAL TO THE AJC

The company declined the AJC’s request for additional documentation that might show the plant fully ceased operations after the accident. The state Environmental Protection Division said it could not independently verify whether the plant had closed or suspended operations.

“The bottom line is that Sterigenics is focused on the safety of its employees and its communities as it sterilizes vital medical products and devices,” a company spokesman wrote in an email to the AJC. “The company did not waiver from that focus in its response to this unfortunate incident.”

Sterigenics has been targeted by protesters who want the Cobb County plant shut down because of permitted emissions of ethylene oxide. Two state lawmakers have also called on Gov. Brian Kemp to shut down the plant.

The July 10, 2018, explosion occurred around 3:30 a.m. in one of the plant’s sterilization chambers, sending a worker to the hospital. The incident was reported to the National Response Center, which handles toxic spills, about 18 hours later at 9:20 p.m., according to the state EPD.

When the EPD established contact with a company representative the next day, Sterigenics told the agency that no reportable release of ethylene oxide had occurred, and the state closed the case. The company is required to report leaks immediately if it cannot determine how much of the chemical has been released, or if it’s greater than 10 pounds.

The state found that Sterigenics failed to report a separate leak in April 2018, and warned that it could face fines if future leaks went unreported.

The federal Department of Labor did not open its inquiry into the explosion until July 16, nearly a week after the incident. That inquiry was closed in January 2019 with no issuance of citations against the company. The AJC is waiting for the agency to issue the full report in response to a Freedom of Information Act request.