Popcorn Lung: It’s Not Just a Butter-Flavoured Problem Anymore

It has been 13 years since the National Institute for Occupational Safety and Health (NIOSH) published the first reports of a potentially deadly lung disease in workers at a microwave-popcorn factory. The newly identified lung disease, sometimes called “popcorn lung,” was officially dubbed bronchiolitis obliterans for its devastating effect on the lungs. It was eventually linked to diacetyl, a chemical used to create butter flavour in prepared foods. So, it’s not news that exposure to aerosolised flavourings containing diacetyl causes devastating lung disease. But the latest news on diacetyl will take even more workers’ breath away. Until now, problematic diacetyl exposures were believed to be connected with added flavourings. But diacetyl occurs naturally as a by-product of fermentation. It is present in many foods containing no added flavours, 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 flavourings may be exposed to dangerous levels. 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. Although reported lung disease clusters have not yet implicated food processors that don’t use flavour 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. Even workers in industries that don’t use diacetyl or related chemicals in concentrated form as flavour additives may be taking their coffee (or dairy products, or alcoholic beverages) with added lung disease. 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.

Environmental Health & Safety Daily Advisor, 21 October 2015 ;http://ehsdailyadvisor.blr.com/ ;