USA – Didion Milling yet to act on nine CSB safety recommendations years after deadly explosion

The U.S. Chemical Safety and Hazard Investigation Board (CSB) has reported that Didion Milling has not implemented any of the nine safety recommendations it issued following the agency’s probe into the May 2017 explosions at the company’s Cambria, Wisconsin plant. The incident claimed five workers’ lives and left 14 others with serious injuries.

The recommendations were included in the CSB’s final report, released in December 2023. Despite repeated attempts to engage with the company, the agency says it has not received a meaningful response or evidence of progress on the safety measures.

The CSB first outlined its recommendations in a December 11, 2023 letter sent by Director of Recommendations, Charles Barbee, to company president Riley Didion. However, Didion never replied directly. Instead, seven months later, the CSB received a letter from the company’s attorneys that did not address the recommendations in substance.

In their response, Didion’s legal representatives argued that the company’s compliance efforts with a settlement agreement with the Occupational Safety and Health Administration (OSHA) also covered the CSB’s recommendations. OSHA’s settlement, which addressed 14 willful and five serious violations and imposed more than $1.8 million in civil penalties along with criminal penalties, was limited to OSHA’s regulatory requirements. The CSB noted that its own recommendations went further, highlighting broader shortcomings in Didion’s safety management practices that were not tied solely to regulatory violations.

Afterward, Barbee sent a follow-up letter on September 11, 2024, requesting documentation to evaluate Didion’s progress. No reply was received. The CSB says other efforts to reach company leadership, including phone calls and emails, have also gone unanswered.

Most recently, on August 5, 2025, CSB Executive Director of Investigations and Recommendations, Stephen Klejst, again urged Riley Didion to respond, warning that if no action is taken, the agency may formally close the recommendations under the designation “Closed – Unacceptable Response/No Response Received.”

CSB Chairperson Steve Owens emphasized the importance of the process, stating that while the board cannot issue fines or citations, its safety recommendations remain the agency’s primary tool to help prevent future tragedies. “Most companies willingly act on the safety measures we recommend following investigations,” Owens said. “We urge Didion to constructively respond and move toward implementing these recommendations.”

Photo credit: CSB. All rights reserved.