National Institute for Occupational Safety and Health (NIOSH) investigations have shown that sufficient levels of work-related exposure to certain chemical vapors in flavorings can cause severe, irreversible lung disease. These chemicals, diacetyl and its closely related substitute 2,3-pentanedione, can be added to flavorings like the butter in microwave popcorn. The disease, technically called obliterative bronchiolitis, is sometimes called “popcorn lung” because scientists originally described it in workers who manufactured microwave popcorn.

A recent NIOSH study tested various coffee flavoring samples for these chemicals and compared the findings to ingredients on safety data sheets required by the Occupational and Health Administration (OSHA). Study lead author, Ryan LeBouf, NIOSH research industrial hygienist, explains the study published in the  Annals of Work Exposure and HealthExternal.

Q: Why did you do this study?

A:  Diacetyl and 2,3-pentanedione are volatile organic chemicals often included in flavorings used in food products. While considered safe for consumption, these chemicals evaporate at room temperature, presenting the risk of exposure in workplaces where these flavorings are used. It is important to identify which flavorings contain diacetyl and 2,3-pentanedione, so employers and workers can take appropriate precautions to prevent exposure during manufacturing and production.

The problem is that safety data sheets do not always include this information. For example, diacetyl and 2,3-pentanedione might not be listed individually even though each are components of listed ingredients. Chemicals considered proprietary, or trade secret, also can be omitted, as can chemicals comprising less than 1% of a mixture. Finally, authors of safety data sheets might not list diacetyl and 2,3-pentanedione if they don’t recognize them as potentially hazardous.

Q: How did you do the study?

A: We took samples of 26 liquid flavorings from two coffee roasting and packaging facilities. The flavorings included hazelnut, French vanilla, amaretto, chocolate, and caramel, and fruit-flavored mixtures such as cherry and raspberry. We tested the samples for 20 volatile organic compounds, including diacetyl and 2,3-pentanendione, using a highly-specific laboratory test called gas chromatography-mass spectrometry, which detects even minute amounts of various substances in a mixture. Finally, we compared our chemical measurements to the ingredient list on the safety data sheets provided by the flavoring manufacturers.

Q: What did you find?

A: None of the safety data sheets listed diacetyl or 2,3-pentanedione, yet our measurements found these chemicals in nearly all of the flavorings: 81% contained diacetyl and 58% contained 2,3-pentanedione. The amount varied, with caramel flavoring having the most diacetyl, and oatmeal cookie flavoring having the most 2,3-pentanedione. Each safety data sheet stated their ingredients contained trade secrets.

Q: What are the implications?

A: Employers and employees should know that flavoring mixtures can contain chemicals that are potentially hazardous if breathed in, even if those chemicals are not listed on the safety data sheets. Exposures to vapors arising from the flavorings can be minimized through engineering and work practice controls and, potentially, other measures. Those who want more information can find it on the NIOSH website.

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