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General Description

  • Synonyms: Biacetyl; 2,3-Butanedione; 2,3-Butadione; 2,3-Diketobutane; Dimethyl diketone; Dimethylglyoxal; Glyoxal, dimethyl-
  • OSHA IMIS Code Number: D740
  • Chemical Abstracts Service (CAS) Registry Number: 431-03-8
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: EK2625000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 2346 127

Exposure Limits and Health Effects

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Exposure Limit Limit Values HE Codes Health Factors & Target Organs
OSHA Permissible Exposure Limit (PEL) - General Industry Not established    
OSHA PEL - Construction Industry Not established    
OSHA PEL - Shipyard Employment Not established    
National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) 5 ppb (0.005 ppm) 8-hr TWA

Action Level is 2.6 ppb (0.0026 ppm)

25 ppb (0.025ppm) 15-min STEL

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2011)
  • 0.01 ppm
  • (0.04 mg/m3)
  • TWA
  • 0.02 ppm
  • (0.07 mg/m3)
  • STEL
  • A4


Lung damage (bronchiolitis obliterans-like illness)
CAL/OSHA PEL Not established    
  • National Toxicology Program (NTP) carcinogenic classification: Not listed
  • International Agency for Research on Cancer (IARC) carcinogenic classification: Not listed
  • U.S. Environmental Protection Agency (EPA) carcinogenic classification: Not listed
  • EPA Inhalation Reference Concentration (RfC): Not established
  • Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): Not established
  • NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): Not established
  • Notes:
    1. Diacetyl is highly flammable and vapor/air mixtures are explosive. Heating may cause violent combustion or explosion, and it reacts violently with strong acids, strong bases, and oxidants (NIOSH/IPCS 2009).
    2. A cause-effect relationship between diacetyl and bronchiolitis obliterans is difficult to assess because of mean diacetyl exposure levels ranging over four orders of magnitude for workplaces with affected individuals. In addition, food-processing and flavor-manufacturing employees with this lung disease were exposed to other volatile agents (CDC 2007; Kanwal et al. 2006; Kreiss et al. 2002; Kullman et al. 2005; NIOSH 2004, 2006).
    3. Workers at a microwave popcorn production plant exposed to airborne diacetyl had an increased prevalence of many health effects, including unusual fatigue (Kreiss et al. 2002).
    4. Workers exposed to diacetyl may experience skin irritation (NIOSH 2004).
    5. Some workers affected by bronchiolitis obliterans may experience fever, night sweats, and weight loss (NIOSH 2006).
    6. Laboratory studies of diacetyl administered by inhalation show destruction of the lining of the respiratory system (Hubbs 2008).
  • Literature Basis:
    • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Diacetyl. 2012.
    • CDC: Fixed obstructive lung disease among workers in the flavor-manufacturing industry - California, 2004-2007. MMWR 56(16): 389-393, 2007.
    • Hubbs AF, Goldsmith WT, Kashon ML, Frazer D, Mercer RR, Battelli LA, Kullman GJ, Schwegler-Berry D, Friend S, Castranova V Respiratory toxicologic pathology of inhaled diacetyl in sprague-dawley rats.:, Toxicologic Pathology Vol. 36 (2), pp. 330-44.
    • Kanwal, R. et al.: Evaluation of flavorings-related lung disease risk at six microwave popcorn plants. J. Occup. Environ. Med. 48(2): 149-157, 2006.
    • Kreiss, K., Gomaa, A., Kullman, G., Fedan, K., Simoes, E.J. and Enright, P.L.: Clinical bronchiolitis obliterans in workers at a microwave-popcorn plant. New Eng. J. Med. 347(5): 330-338, 2002.
    • Kullman, G., Boylstein, R., Jones, W., Piacitelli, C., Pendergrass, S. and Kreiss, K.: Characterization of respiratory exposures at a microwave popcorn plant with cases of bronchiolitis obliterans. J. Occup. Environ. Hyg. 2(3): 169-178, 2005.
    • NIOSH: Preventing Lung Disease in Workers Who Use or Make Flavorings. NIOSH Publication No. 2004-110. 2004.
    • NIOSH: Safety and Health Topic - Flavorings-Related Lung Disease. 2006.
    • NIOSH/IPCS: International Chemical Safety Cards - 2,3-Butanedione. April 2009.
  • Date Last Revised: 9/6/2012

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • Two specially dried Silica Gel Tubes in series. Each tube has a single 600-mg 20/40 mesh section and a glass-fiber filter, the filter faces forward when sampling. SKC 226-183, or equivalent. Use an opaque tube holder or wrap tubes with aluminum foil or other opaque material while sampling.
  • maximum volume: 9 liters
  • minimum flow rate: 0.05 L/min for long-term sampling; 3 liters at 0.2 L/min for short-term sampling.
  • note: Separate the two tubes and cap both ends of each tube as soon as possible after sampling. Individually seal the two tubes. Protect tubes from light after sampling.
  • analytical method 1:
    • Gas Chromatography; GC/ECD
    • analytical solvent: (95:5) ethanol:water with 2 mg/mL PFBHA reagent
    • method reference: OSHA Analytical Method (OSHA 1012)
    • method classification: Fully Validated
  • analytical method 2:
    • Gas Chromatography; GC/FID
    • analytical solvent: (95:5) ethanol:water
    • method reference: OSHA Analytical Method (OSHA 1013)
    • method classification: Fully Validated
Laboratory Sampling/Analytical Method:
  • Two Silica Gel Tubes in series (150/75 mg sections, 20/40 mesh) Use an opaque tube holder or wrap tubes with aluminum foil or other opaque material while sampling.
  • analytical solvent: (95:5) ethanol:water
  • maximum volume: 3 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • method reference: OSHA Analytical Method (OSHA PV2118)
  • method classification: Partially Validated
  • note: Separate the two tubes and cap both ends of each tube as soon as possible after sampling. Individually seal the two tubes. Protect tubes from light after sampling.

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