Givaudan Plant Explosion Was a Catastrophe Waiting to Happen, Says U.S. Safety Board Final Report

The U.S. Chemical Safety and Hazard Investigation Board (CSB) released its final report on Wednesday 27 May 2026 into the fatal explosion at the Givaudan Sense Colour plant in Louisville, Kentucky, on 12 November 2024. The report concluded the explosion was "a catastrophe waiting to happen" and identified a series of engineering and regulatory failures that led to the deaths of two workers.

What happened at the Givaudan plant

On 12 November 2024, Batch Reactor Six at the Givaudan Sense Colour facility in Louisville's Clifton neighbourhood experienced a runaway chemical reaction while producing caramel colouring for a food product. The reactor, a 2,500-gallon vessel originally constructed in 1978, reached a temperature of 385 degrees Fahrenheit - 30 degrees above its maximum allowable working temperature - and a pressure of 237 psi, more than three times its maximum rated pressure.

The reactor's emergency pressure relief system was overwhelmed by the rate of pressure increase and failed to prevent a catastrophic rupture. Debris was ejected more than 400 feet beyond the facility's fence line into the surrounding residential neighbourhood. Local authorities issued a shelter-in-place order for a one-mile radius around the facility.

Two workers were killed. Three others were seriously injured. Four additional employees were inside the control room at the time of the explosion and were among those injured.

What the CSB final report found

The CSB's investigation identified the immediate cause as a runaway exothermic chemical reaction inside Reactor Six that the reactor's pressure relief system was fundamentally unable to handle. The relief system would have needed to be approximately four times larger to safely manage the pressure generated by that type of reaction.

The reactor had a significant history before arriving at the Louisville facility. Built in 1978, it operated at a separate plant until that facility closed in 2008, at which point Reactor Six was relocated to Louisville and kept in storage. In 2021 it was modified and installed at the Louisville plant to meet current operational requirements. The CSB found that Givaudan did not adequately assess the pressure relief requirements for the reactor given the specific chemical reactions it was being used to carry out at the Louisville facility.

CSB Chairperson Steve Owens said: "This tragic incident was a catastrophe waiting to happen. The reactor's pressure relief system was not designed to release pressure from a reaction like this, and Givaudan did not recognise that hazard."

CSB Board Member Sylvia Johnson added: "This tragedy demonstrates that companies handling reactive chemical processes must fully understand the hazards of their materials, implement effective safeguards, and ensure that workers and surrounding communities are protected from catastrophic events."

CSB recommendations

The final report sets out a series of recommendations directed at Givaudan, the U.S. Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). These include:

• Larger emergency pressure relief systems on batch reactors handling reactive chemical processes
• Mandatory facility siting analyses to ensure control rooms and regularly occupied areas are located at a safe distance from high-hazard equipment
• Safer facility design requirements for plants handling reactive chemistry
• Regulatory changes by the EPA and OSHA to prevent similar incidents at other facilities

The plant's history and current status

The Givaudan facility in Louisville had a prior safety record of concern. In April 2003, when the site was owned and operated by D.D. Williamson, a separate explosion killed one person after a process vessel became overpressurised. In May 2023, the plant was cited by the Louisville Air Pollution Control District for failing to provide compliance reports for air quality control operations.

Following the November 2024 explosion, Givaudan ceased operations at the facility. Demolition of the plant began in January 2026 and is now complete. The company has confirmed it does not intend to rebuild at the Louisville site.

Givaudan is a Swiss multinational company and one of the world's largest producers of flavours and fragrances, with operations across Africa, Australia, Asia, Europe and the Americas. The Louisville facility was part of its Sense Colour division, which produces food colouring ingredients.

Wider significance

The CSB is an independent federal agency that investigates chemical accidents at fixed facilities in the United States. Its reports carry no enforcement power but carry significant weight with regulators and industry. The Givaudan report is one of a series of CSB investigations in recent years highlighting the risks of reactive chemistry in batch manufacturing environments.

The findings echo a pattern identified across multiple CSB investigations: ageing reactors transferred between facilities without adequate re-assessment of pressure relief requirements, and control rooms sited too close to high-hazard equipment. The recommendation for regulatory changes by the EPA and OSHA signals that the CSB regards existing rules as insufficient to prevent equivalent incidents at other facilities across the United States.

What caused the Givaudan plant explosion?

The CSB found the explosion was caused by a runaway chemical reaction inside a 2,500-gallon batch reactor producing caramel colouring. The reactor's pressure relief system was not designed to handle the pressure generated by that type of reaction and failed, causing a catastrophic rupture. The relief system would have needed to be four times larger to function safely.

How many people were killed in the Givaudan explosion?

Two workers were killed in the 12 November 2024 explosion at the Givaudan Sense Colour plant in Louisville, Kentucky. Three others were seriously injured. Additional employees in the control room at the time were also among those injured.

What is the Chemical Safety Board?

The U.S. Chemical Safety and Hazard Investigation Board (CSB) is an independent federal agency that investigates accidental releases of hazardous chemicals at fixed industrial facilities. It issues findings and recommendations to industry and regulators but does not have enforcement powers. It is funded by the U.S. federal government and operates independently of the EPA and OSHA.