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NCA Industry Resource Guide Diacetyl

NCA Industry Guide: Diacetyl


Diacetyl is a chemical compound formed naturally in the production of many foods and beverages, including milk, cheese, yogurt, coffee, citrus juices, vinegar, whiskey, wine – and coffee.

The compound is deemed safe for consumption by the U.S. Food and Drug Administration, which maintains that there is no evidence suggesting a hazard to the public as consumed. However, issues have arisen related to inhalation of diacetyl during food processing in the workplace.

Diacetyl At-A-Glance

☕   Diacetyl is a natural compound created by cooking and processing of many foods, including butter, milk, wine and roasted coffee.  It also has historically been used as an additive in some flavoring compounds.

☕   There is no established scientific evidence that naturally occurring diacetyl causes lung disease.

☕   Historically, workplace exposure studies focused on artificial diacetyl added as a flavoring, which is where links to lung disease were suggested.

☕   Scientific recommendations on safe levels of diacetyl in the workplace vary widely, including NIOSH’s 5 parts per billion (ppb) time-weighted average over an eight-hour workday, 10 ppb by the American Conference of Governmental Industrial Hygienists (AGGIH), 170 ppb by the European Food Safety Authority, and 200 ppb by leading independent scientists. 

☕   Given the extreme variation in recommendations, the National Coffee Association (NCA) has commissioned an independent toxicological study that comprehensively examined all research to recommend a scientifically based workplace exposure level. The study is complete, has been reviewed by two additional independent experts, and will be submitted for formal peer review leading to publication in a scientific journal, anticipated in early 2018.

☕   In the meantime, roasters are urged to learn more about this subject, including by reviewing the resources below. Roasters may also consider engaging an industrial hygienist to examine their plant and make safety suggestions.