Didion Milling Fails to Implement the U.S. Chemical Safety Board’s Recommendations to Improve Safety at Wisconsin Facility Where Explosions Killed Five Employees and Injured 14 Others
Washington, D.C. August 11, 2025 –The U.S. Chemical Safety and Hazard Investigation Board (CSB) said today that Didion Milling, Inc. has so far failed to implement nine safety recommendations made by the CSB stemming from the agency’s investigation of the fatal May 2017 explosions at Didion’s Cambria, Wisconsin, facility that left five employees dead and 14 others seriously injured. The CSB made the safety recommendations to Didion in December 2023, as part of the agency’s final report on the fatal incident. To date, however, Didion has not implemented any of the safety recommendations, and the CSB has not received an adequate response from Didion about the status of the safety recommendations, despite multiple outreach efforts to the company by the CSB.
The CSB formally transmitted the safety recommendations to Didion in a letter dated December 11, 2023, from the CSB’s Director of Recommendations, Charles Barbee, to Riley Didion, the company’s president. Didion itself has never responded to the CSB’s letter. Instead, after nearly seven months, on July 9, 2024, the CSB received a letter from Didion’s attorneys that did not substantively address the CSB’s safety recommendations. Didion’s attorneys claimed that Didion’s steps to address a settlement agreement with the Occupational Safety and Health Administration (OSHA) also addressed the CSB recommendations. However, while OSHA’s agreement addressed 14 willful citations and five serious citations resulting in more than $1.8 million in civil penalties, in addition to subsequent criminal penalties, the OSHA citations solely addressed violations of OSHA’s regulations. In contrast, the CSB recommendations addressed various other identified gaps in Didion’s inadequate safety management system as well as the company’s failure to properly implement other safety standards and guidance, regardless of whether they violated existing statutes or regulations.
After receiving the attorneys’ letter, Director Barbee sent another letter on September 11, 2024, to Riley Didion, outlining the information and documentation necessary for the CSB to evaluate Didion’s progress in addressing the CSB’s safety recommendations. To date, Didion has never responded to that letter and has not provided any of the information or documentation requested by the CSB. In addition to the letters, the CSB has made several other attempts to engage with Didion’s leadership about the safety recommendations, including phone calls and emails, that also have gone unanswered.
Last week, on August 5, 2025, the CSB’s Executive Director of Investigations and Recommendations, Stephen Klejst, sent a letter to Riley Didion again requesting a response to the nine safety recommendations and offering Didion a final opportunity to respond. If Didion fails to respond again and takes no action to implement any of the safety recommendations, the CSB Board may decide to close the recommendations with a formal designation “Closed - Unacceptable Response/No Response Received”.
CSB Chairperson Steve Owens stated, “Most companies willingly implement the safety recommendations that they receive as a result of the CSB’s investigations. Because the CSB is a nonregulatory agency that does not issue fines or citations, safety recommendations are the primary tool that the agency has to help prevent future horrific incidents that kill and seriously injure people like the massive explosions that occurred at Didion’s facility. We urge Didion to respond constructively and take action toward implementing these recommendations.”
The CSB is an independent federal agency charged with investigating incidents and hazards that result, or may result, in the catastrophic release of extremely hazardous substances. The agency’s core mission activities include conducting incident investigations; formulating preventive or mitigative recommendations based on investigation findings and advocating for their implementation; issuing reports containing the findings, conclusions, and recommendations arising from incident investigations; and conducting studies on chemical hazards.
The agency's board members are appointed by the president subject to Senate confirmation. The Board does not issue citations or fines but makes safety recommendations to companies, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA.
Please visit our website, www.csb.gov. For more information, contact Communications Manager Hillary Cohen at [email protected].