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[L]ast month, the Center for Disease Control’s National Institute of Occupational Safety and Health created a website that details the potential risk of exposure to diacetyl and 2,3-pentanedione during coffee roasting and processing and proposes exposure limits for workers. While research over the past decade has shown severe risks associated with flavorings that contain the two related compounds, which are produced naturally during roasting, tests showing unsafe levels in facilities that process unflavored coffee are relatively new.

Diacetyl and 2,3-pentanedione are both volatile compounds belonging to a larger category known as alpha-diketones, and they were often part of the chemical makeup of food flavorings. The danger of diacetyl first made headlines in 2000 when popcorn factory workers were shown to disproportionately suffer obliterative bronchiolitis, an irreversible and potentially fatal lung disease. Diacetyl was used in butter flavoring, and they caused scarring in the airways of workers’ lungs, marked by coughing and shortness of breath during even mild exertion. The flavorings that contained the chemicals have been largely abandoned by food processors, except in the coffee industry.

That was known. The new material released by NIOSH shows that there may be concern even for unflavored coffee processing facilities.

I would certainly be appalled if people didn’t feel the need to follow up on this at all

A coffee processing plant in Texas first requested a health hazard evaluation by the NIOSH after five workers were diagnosed with obliterative bronchiolitis. Air sampling at the plant found elevated levels of diacetyl and 2,3-pentandione throughout the facility, particularly in areas where unflavored coffee was ground,  packaged,, or stored to off-gas. Elevated alpha-diketone levels were also found in areas where flavoring chemicals were added to roasted coffee.

“When you looked at the amount of diacetyl and 2,3-pentanedione in the non-flavored area and the flavored area and added them up cumulatively, [the chemical levels] were comparable in the flavored area and the non-flavored area,” says Dr. Rachel Bailey, a medical officer in the NIOSH Respiratory Health Division who helped lead the initial evaluation.

Bailey says that while the isolated case in Texas cannot be applied to all coffee processing facilities, levels were beyond the published NIOSH recommendations. Currently, NIOSH is conducting evaluations at ten other roasting facilities that include a range of building sizes and production volumes to better gauge what environmental factors might increase the presence of diacetyl and 2,3-pentandione in the workplace.

“What we’re learning when we go to all of these other facilities is what are the levels?” says Bailey. “Are they high? Is this particular plant [in Texas] an outlier, or is this something we’re going to see? We just don’t know until we look at more facilities.”

Until more evidence shows a pattern of elevated alpha-diketone levels in roasteries, coffee industry representatives aren’t ready to hit the panic button. “There is currently no epidemiology to suggest that there is even an unmodulated risk,” says Ric Rhinehart, executive director of the Specialty Coffee Association of America.

Rhinehart explains that caution is important, but doesn’t feel that roasters or consumers have reason to be concerned unless additional testing finds elevated levels of these compounds across facilities that process unflavored coffee. He supports the further investigations, saying, “I would certainly be appalled if people didn’t feel the need to follow up on this at all.

“I’m in favor of caution on these things, but I don’t think people should be panic-stricken,” he says. “These compounds are super soluble in air and easily dispersed with good ventilation.”

Information will become more clear in the coming months as the CDC tests facilities, including cafés with in-house roasting equipment.

Bailey also stressed the importance of good ventilation. According to Bailey, engineering controls, such as proper ventilation, are an important part of ensuring safety for employees in coffee processing facilities. Employees are covered by right-to-know laws, in compliance with the Hazard Communication Standard established by the Occupational Safety and Health Administration. Under these these laws, anyone working at a coffee facility should be aware of what they could potentially be exposed to, including alpha-diketones that may be released as off gas during roasting.

Organizations can request health hazard evaluations for their workplace, as can employees. After an HHE is filed, program representatives decide whether an on-site evaluation is needed. Once on site, tests and measurements, in addition to other evaluation methods, are used to evaluate potential health hazards. Follow-up reports are released directly to the organization.

According to Bailey, NIOSH will begin a series of tests in facilities during March and April. Though interim reports will be released, Bailey was unable to estimate a timeline of when preliminary results might be available.

In the meantime, Bailey recommends roasters address any specific concerns. “If somebody works in a coffee facility and they’re having respiratory symptoms, cough, shortness of breath, maybe wheezing, they should be evaluated,” says Bailey. “Their symptoms may be unrelated to work, but they could be. It’s better to be evaluated just to be sure.”

Rhinehart agrees that concerns from employers or workers in the coffee industry should not be ignored. “Anyone with concerns about diacetyl would be well served to contact an industrial hygeniest,” he says. “In industrial coffee production, it would be reasonable for an operator to have an assessment done by an industrial hygienist and have risks mitigated appropriately,” he says.

Information will become more clear in the coming months as Bailey and her team test facilities, including cafés with in-house roasting equipment. “We’ll likely be doing some sampling in those areas in some of the facilities so we’ll have a better gauge of what’s going on,” she says.

The SCAA doesn’t see any cause for concern among consumers, whether they grind coffee at home or frequent neighborhood roasteries with attached retail cafés. “There definitely shouldn’t be any concern from the consumer standpoint,” says Rhinehart. “The quantity of coffee you’d have to grind to get to dangerous levels is not something that consumers will encounter.”

While consumers should not be alarmed by these reports, employee concerns about diacetyl and 2,3-pentandione warrant further investigation, particularly in high-volume roasting facilities with poor infrastructure. Until researchers compile a more comprehensive report based on upcoming testing, it remains unclear whether the documented cases are part of a widespread problem or are outliers.

Ellie Bradley is Fresh Cup’s associate editor.

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