Diacetyl is a chemical used to add flavor and aroma to food and other products. Some workers who breathe diacetyl on the job have become disabled or have died from severe lung disease. Some manufacturers of microwave popcorn now use diacetyl substitutes such as 2,3-pentanedione, diacetyl trimer and acetoin, among others. Recent studies have shown that 2,3-pentanedione has produced similar health effects as diacetyl and, therefore, also may cause harm to workers.

“It is alarming that workers continue to be at risk of dying from exposure to diacetyl and diacetyl substitutes,” said OSHA Administrator Dr. David Michaels. “Illnesses and death from these chemicals are preventable and this revised directive will help ensure that employers use necessary measures to protect workers from this hazard.”

OSHA’s efforts to minimize or eliminate workers’ exposure to microwave popcorn manufacturing hazards include inspection targeting, directions for controlling chemical hazards and extensive compliance assistance. Inspections conducted under this NEP will target facilities where workers are manufacturing or processing microwave popcorn.

Currently, OSHA has permissible exposure limits (PEL) for some diacetyl substitutes, but most flavorings do not have PELs. Additionally, microwave popcorn manufacturing facilities are subject to other applicable OSHA mandatory standards including Respiratory Protection and Hazard Communication.

For more safety and health information on diacetyl and other food flavorings, visit OSHA’s Safety and Health Topics page on Lung Disease Related to Butter Flavorings Exposure. The agency’s Safety and Health Information Bulletin and companion Worker Alert recommend engineering and work practice controls for regulating diacetyl and diacetyl substitute exposures in the workplace.

Click here to download a PDF about the revised directive.