Naturally Occurring Diacetyl Exposure-July 2017

Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety

July 2017

IN THIS ISSUE: Naturally Occurring Diacetyl Exposure

Concern for employees working in facilities that produce flavored foods, such as popcorn, is nothing new. After extensive testing, diacetyl, a key ingredient in food flavorings was linked to obliterative bronchiolitis, a rare irreversible disease of lung airways that severely impairs breathing. In October 2016, NIOSH published a criteria document which recommended lower exposure limits for diacetyl and related chemicals, at facilities manufacturing flavored foods took heed.

But what could explain employee exposure to diacetyl and other chemicals when flavoring is not part of the manufacturing process?

During recent testing at a coffee roasting operation, high levels of employee exposure to diacetyl, along with 2,3-pentandione and acetone – two other chemicals that may cause obliterative bronchiolitis – were found. Although flavoring is used in some coffees, during testing, no flavoring was added. Unexpectedly, results for both diacetyl and 2,3-Pentanedione were double current occupational exposure standards. The data show that these chemicals naturally occur in coffee and the use of flavoring only added to the exposure. In the roasting process, large surface areas of coffee beans are open to the air, particularly during cooling and grinding, which accounted for the high exposures. Further engineering controls such as local exhaust ventilation were recommended.

NIOSH’s Recommended Exposure Limit (REL) was lowered in 2016:

  • Diacetyl: 5 parts per billion; 15-minute exposure limits of 25 ppb
  • 2,3-Pentanedione: 9.3 ppb; 15-minute exposure limits of 31 ppb

The report emphasized the relationship between flavorings and obliterative bronchiolitis. NIOSH also cited a study at a coffee manufacturing facility in Texas that was conducted after five former workers developed the disease.  The tests found very high exposure levels of exposure to Diacetyl and 2,3-Pentandione in flavoring rooms and grinding areas.

It is evident from both the work of NIOSH and my own testing, that employers in coffee manufacturing need to take quick action to evaluate the exposure levels in their processes, provide respiratory protection and medical monitoring of employees, and evaluate engineering controls. This should be done whether or not flavorings are used in the coffee manufacturing process.

For more information on this topic and to discuss your company’s safety and industrial hygiene needs call OccuSafe at (214) 662-6005 or visit us at


OccuSafe Industrial Hygiene & Safety, Inc. provides skills and expertise to recognize, evaluate and control hazards and injuries in the areas of industrial hygiene, occupational safety and health. OccuSafe services companies of all sizes in a range of industries.

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