Diacetyl Hazards in Coffee And E-Cigarettes? Expert Article

In this article, Industrial Hygienist, Ronald Schaible, CIH, CSP, provides an introduction to diacetyl hazards as they relate to coffee and e-cigarettes. His discussion includes an explanation of the hazards as well as industry safety practices for protecting workers.

Diacetyl Expert Witness

Diacetyl Hazards in Coffee and E-Cigarettes?

Diacetyl (also known as 2,3-Butanedione) is one of the volatile organic compounds (VOCs) used as ingredients in flavorings. Flavorings are complex mixtures of natural and manmade ingredients that are added to many food products in the production process. Prior to 2000, there was no reported inhalation hazard data for diacetyl. Attention was drawn to the potential hazards of flavorings when there were occurrences of respiratory illness/injury observed in the microwave popcorn industry, particularly in slurry/flavoring rooms where temperatures above ambient are common, and in packaging lines where the slurry is pumped into the bags of popcorn. More recently, similar worker health concerns have been expressed about exposure to flavorings used in processing coffee beans and in e-cigarette products. In the processing of coffee beans, diacetyl and 2,3-pentanedione are naturally produced and released during the roasting, grinding, flavoring and packaging processes. Grinding roasted coffee beans produces greater surface area for the off-gassing of these and other chemicals. Recent information from the National Institute for Occupational Safety and Health (NIOSH) shows there may be concern even for unflavored coffee processing facilities. Currently there are reportedly more than 7,000 e-cigarette flavorings being marketed. Diacetyl is one chemical that has been present in chemical analyses of these flavors at levels that exceed the laboratory limit of detection. The chemicals are subject to inhalation and ingestion into the body.


Diacetyl, along with other VOCs such as 2,3-pentanedione and other alpha-diketones, have been associated with bronchiolitis obliterans (a/k/a severe fixed obstructive lung disease, or “Popcorn Lung”) which is an irreversible lung disease. Exposed manufacturing workers may experience restrictive breathing anomalies or decreased lung function. The likelihood of exposure increases in high-volume roasting facilities with poor infrastructure. Exposure may not be limited to manufacturing environments. It is currently uncertain if a consumer hazard exists with respect to microwave popcorn consumption or home roasting of coffee.


Best practices have been established to eliminate or minimize potential exposure to flavorings in manufacturing processes. These practices include engineering controls, improved work practices, use of personal protective equipment (PPE), and exposure monitoring. One potential engineering control is substitution of diacetyl with other substances, although the safety of those substitutes should be demonstrated by toxicology studies. Another engineering control is to use closed systems wherever practical to prevent the release of contaminants in the work environment. Local exhaust ventilation can be used at process locations where gases and vapors are or may likely be released. If exposure monitoring indicates the potential for exposure above accepted Occupational Exposure Limits (OELs), then proper respiratory protection should be implemented until satisfactory exposure levels are achieved. Worker training in accordance with OSHA’s hazard communication standard (29 CFR 1910.1200) is also required. This training should use suppliers’ Safety Data Sheets (SDS) and product labels and warnings to convey the proper safety messages. SDS are used as a training and reference tool for workers, and health, safety, and environmental professionals. SDS cannot include information on every unique application of the material, although they should consider the hazardous exposures resulting from customary and reasonably foreseeable use, misuse, handling, and storage. Manufacturers of flavorings should ensure that their SDS and warnings convey proper hazard information in accordance with prevailing industry consensus standards.

Workplace Safety Investigations

The multidisciplinary workplace safety group at Robson Forensic includes professional engineers, hazardous material management professionals, occupational safety specialists, toxicologists, and certified industrial hygienists. We evaluate complex human health and safety issues including chemical and biological exposures, industrial machine mishaps, and a variety of other workplace safety issues. For more information, visit our Workplace Safety practice page.

Featured Expert

Ronald D. Schaible, Industrial Hygienist, Workplace Safety & Ergonomics Expert

Ronald D. Schaible, CIH, CSP, CPE

Industrial Hygienist, Workplace Safety & Ergonomics Expert
How do you match the experience of an individual who developed and deployed the global health and safety management system for a Fortune 500 company with 250 locations in 50 countries? Or one that has… read more.


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