There are few aromas as potent as coffee beans being roasted, ground, or brewed. But for the hardworking roasters, grinders, and packers who make that olfactory experience possible for you every morning, it could be more toxic than intoxicating.

According to a recent report from the Centers for Disease Control and Prevention (CDC), potentially harmful chemicals called alpha-diketones were found at higher-than-expected levels at an unnamed coffee processing facility, leading the organization to issue a warning about the potential occupational hazards of processing coffee.

The CDC evaluated the respiratory health of 16 workers at a facility which roasts, grinds, and packages coffee. Investigators collected air samples as well as roasted coffee beans to measure the emission levels of alpha-diketones such as diacetyl and 2,3-pentanedione, which are typically used to add buttery flavor to things like microwave popcorn, bakery mixes, and artificially flavored coffees.

Diacetyl has been linked to "popcorn lung," the respiratory disease that caused a Colorado man to win $7.2 million in a lawsuit after he almost died from eating a bag of microwave popcorn every day for ten years.

In their report, the CDC quoted a wealth of research confirming that "occupational exposure to diacetyl and 2,3-pentanedione can cause loss of lung function and the lung disease obliterative bronchiolitis" and noted that these chemicals are "naturally produced when coffee beans are roasted, and grinding the roasted coffee beans produces greater surface area for the off-gassing of these chemicals"

Photo via Flickr user Rob Taylor

The CDC had already linked alpha-diketones and lung disease in coffee processing facilities, but this most recent report is reportedly the first to reveal diacetyl levels in a plant that "does not add flavors to its coffees." Wheezing and whistling in the chest were the most commonly reported lower respiratory symptoms; with four times as many employees reporting wheezing as would be expected in the general population.

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As for alpha-diketones levels in the air, some employees (roaster operator, grinder operator, and package employees) were exposed to diacetyl at concentrations "above the recommended exposure limit [for an eight-hour work day] for diacetyl of 5 parts per billion, with the highest measured concentration of 8.4 parts per billion."

Does that mean that taking a huge whiff of coffee beans every morning is going to land you with popcorn lung? Probably not. The report quotes the National Institute for Occupational Safety and Health's (NIOSH) prediction that "1 in 10,000 workers exposed to diacetyl at 5 ppb for a 45-year working lifetime would develop more severe lung function reduction." Still, it could have very real health implications for the employees of these processing facilities. When asked what medium- and large-scale producers can do to minimize the exposure of diacetyl for its roasters, the CDC did not mince words.

"If elevated levels of diacetyl (2,3-butanedione) or 2,3-pentanedione are detected in workplace air, workplace interventions should be put in place to reduce the levels," the CDC told us in an e-mail. "The effectiveness of these interventions (e.g., engineering controls, ventilation changes) should be verified by follow-up air sampling. NIOSH has published a best practices document that describes work interventions and exposure monitoring for occupational exposures to diacetyl and 2,3-pentanedione."

Suggestions for improving alpha-diketones safety levels in the case of this specific coffee plant mentioned in the report included operating the exhaust fan and make-up air system in the production space "whenever occupied," installing local exhaust ventilation, training employees about workplace hazards, as well as setting up programs to help employees stop smoking cigarettes. MUNCHIES has reached out to several major coffee roasters for comment on whether they will be taking additional measures to ensure employee safety in the wake of the report, but has not yet received a response.