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So, it’s not news that exposure to aerosolized flavorings containing diacetyl causes devastating lung disease. But the latest news on diacetyl will take even more workers’ breath away.
Naturally Occurring Exposures
Until now, problematic diacetyl exposures were believed to be connected with added flavorings. But diacetyl occurs naturally as a by-product of fermentation. It’s present in many foods containing no added flavors, including beer, wine, cheese, and yogurt. Although harmless when eaten, it’s deadly when inhaled. And recent research indicates that even some food industry workers who don’t handle artificial flavorings may be exposed to dangerous levels.
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An investigation by The Milwaukee Journal-Sentinel in 2015 sampled diacetyl concentrations in the breathing zones of coffee roasters at small-batch operations. The operations were modern, clean, well-ventilated—and the results were shocking. During the roasting and grinding processes, levels of diacetyl and another chemical with a similar structure, 2,3-pentanedione, were present in workers’ breathing zones at levels 40% to 90% higher than current recommended exposure limits.
Where Are the Cases?
Although reported lung disease clusters have not yet implicated food processors that don’t use flavor additives, the data may be deceptive. Bronchiolitis obliterans is often misdiagnosed as occupational asthma or chronic obstructive pulmonary disease, especially in workers who smoke or have other predisposing factors.
The hazards of diacetyl for coffee roasters weren’t identified until a doctor in Texas wondered why a 39-year-old nonsmoking worker who was otherwise healthy had the lung function of a 70-year-old man. The doctor asked to see the safety data sheets from the worker’s job. Four more cases were subsequently identified at the same facility. The fact that cases have not yet been identified doesn’t mean they don’t exist.
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Even workers in industries that don’t use diacetyl or related chemicals in concentrated form as flavor additives may be taking their coffee (or dairy products, or alcoholic beverages) with added lung disease.
Existing Exposure Limits
NIOSH and the American Conference of Government Industrial Hygienists (ACGIH) have published the following relative exposure limit (REL) guidelines:
- NIOSH has proposed an REL of 5 parts per billion (ppb) in air as an 8-hour total weighted average for diacetyl, with a short-term exposure limit (STEL) for diacetyl of 25 ppb for a 15-minute time period. NIOSH has also proposed an REL for 2,3-pentanedione of 9.3 ppb and an STEL of 31 ppb. These RELs are based on the lowest levels at which the substance can be reliably detected rather than on health effects.
- The ACGIH has adopted a threshold limit value of 10 ppb for diacetyl and an STEL of 20 ppb.
Tomorrow, we’ll look at some ways to control worker exposures to diacetyl.