Flavorings Related Lung Disease: Exposure Control

Exposure Control

air handling equipment on roof

NIOSH recommends that employers control occupational exposures to diacetyl and 2,3-pentanedione below recommended exposure limits (RELS). NIOSH has published RELs for diacetyl and 2,3-pentanedione in workplace air (NIOSH 2016-111). The NIOSH objective in establishing RELs for diacetyl and 2,3-pentanedione is to reduce the risk of respiratory impairment (decreased lung function) and the severe irreversible lung disease, obliterative bronchiolitis, associated with occupational exposure to these chemicals. On this basis, NIOSH proposed a REL of 5 ppb for diacetyl and 9.3 ppb for 2,3-pentandione (as a time-weighted average for up to 8 hours/day during a 40-hour workweek).The NIOSH proposed 15-minute short-term exposure limits (STELs) are 25 ppb for diacetyl and 31 ppb for 2,3-pentanedione (NIOSH 2016-111). The NIOSH proposed exposure standards do not differentiate between natural and synthetic chemical origin of diacetyl or 2,3-pentanedione. Currently, there are no occupational exposure limits for 2,3-hexanedione or 2,3-heptanedione. Controlling workplace exposures can be accomplished by implementing standard industrial hygiene practices:

  • Substituting less hazardous material or materials. This step should be completed after carefully evaluating potential substitutes for toxicity.
  • Using engineering controls such as closed systems, isolation, or local exhaust ventilation. A 3-year evaluation of exposure controls implemented at a microwave popcorn production facility, including engineering controls, showed that they markedly reduced air concentrations of flavoring compounds (Kanwal et al. 2011external icon). Additional NIOSH research addresses an especially important potential source of diacetyl exposure, mixing tanks (Hirst et al. 2014external icon). The authors note that when working with flavoring ingredients, the use of closed transfer procedures is the preferred control technique. However, when closed transfer is not in place or feasible, simple, relatively low cost exhaust hoods can provide a reasonably effective approach to controlling evaporative emissions from mixing tanks used in producing flavorings and flavored foods. Other field-based engineering control evaluations showed that reductions in vapor and dust emissions of up to 99% could be achieved for a variety of common processes including benchtop mixing and weighing, bag dumping and filling, and filling mixing tanks (NIOSH 2016-111).
  • Instituting administrative controls such as good housekeeping and work practices which minimize exposure.
  • Educating employers and employees to raise their awareness of potential hazards and training workers on proper procedures and use of engineering controls.
  • Use personal protective equipment, where needed, in addition to primary engineering or administrative controls.
    • Respirators used to minimize exposures to flavoring-related chemicals should protect against both organic vapors and particulate matter. Protection for acid mists may be required, depending on what chemicals are utilized in production.
  • Monitoring occupational exposures and the status of workers’ health, tracking potential symptoms or cases, and reporting such symptoms or cases to NIOSH and state health departments.
    • Workers exposed to flavoring compounds in flavoring manufacturing plants, and workers exposed to butter flavoring compounds in the production of different food products, should have their lung function checked with spirometry on a regular basis to detect abnormalities or excessive declines in lung function that may be work-related.

NIOSH has developed guidance in a variety of areas to reduce workers’ exposures to diacetyl through engineering controls, best work practices, and techniques for monitoring airborne diacetyl exposures. To view the guidelines, visit Best Practices: Engineering Controls, Work Practices, and Exposure Monitoring for Occupational Exposures to Diacetyl and 2,3-Pentanedione. NIOSH does not have authority under the Occupational Safety and Health Act to issue regulations. For information on OSHA’s current policy on regulatory protection for workers exposed to flavorings, see the OSHA flavorings web pageexternal icon.

Workplace Interventions

If levels of diacetyl (2,3-butanedione) or 2,3-pentanedione above the RELs are measured in workplace air, interventions should be put in place to reduce the levels. The effectiveness of these interventions should be verified by follow-up air sampling. Serial air sampling for diacetyl and 2,3-pentanedione can help evaluate the impact of interventions on exposures and identify where to prioritize any future interventions.


1Hirst DV, Dunn KH, Shulman SA, Hammond DR, Sestito N [2014]. Evaluation of engineering controls for the mixing of flavorings containing diacetyl and other volatile ingredients. J Occup Environ Hyg 11(10):680-687.

2Kanwal R, Kullman G, Fedan KB, Kreiss K [2011]. Occupational lung disease risk and exposure to butter-flavoring chemicals after implementation of controls at a microwave popcorn plant. Public Health Rep. 126(4):480-494.

Page last reviewed: October 3, 2017