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n-Butyl Lactate

General Description

  • Synonyms: Butyl alpha-hydroxypropionate; Butyl ester of 2-hydroxypropanoic acid; Butyl ester of lactic acid; Butyl lactate
  • OSHA IMIS Code Number: 0478
  • Chemical Abstracts Service (CAS) Registry Number: 138-22-7
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: OD4025000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 1993 128 (combustible liquid, n.o.s.)
  • NIOSH Pocket Guide to Chemical Hazards, n-Butyl lactate: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 5 ppm, 30 mg/m3 TWA
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 5 ppm, 25 mg/m3 TWA

Health Factors

  • Potential Symptoms: Irritation of eyes, skin, nose, throat; cough, headache, drowsiness, central nervous system depression; nausea, vomiting.
  • Health Effects: Irritation-Eye, Nose, Throat---Moderate (HE15); Headache (HE7)
  • Affected Organs: Eyes, skin, respiratory system, central nervous system
  • Notes:
    1. OSHA does not have a PEL for n-butyl lactate.
    2. n-Butyl lactate is listed among FDA's "food additives permitted for direct addition to food for human consumption" (21 CFR 172.515).
    3. n-Butyl lactate is metabolized in the body to lactic acid and sequentially to n-butanol, n-butyraldehyde, and n-butyric acid. Irritation is likely due to the lactic acid, which is metabolized to pyruvic acid and subsequently to CO2 during energy production. Butyric acid is a substrate for fatty acid synthesis via medium chain acyl-CoA synthetase.
    4. The odor and odor-nuisance thresholds of n-butyl lactate have been reported to be 0.095 and 9 mg/m3, respectively.
    5. Subacute (28-day) inhalation studies in rats indicated a NOAEL for n-butyl lactate of 200 mg/m3 (~33 ppm), with higher concentrations causing mild hyperplasia of nasal epithelium.
  • Literature Basis:
    • NIOSH Pocket Guide to Chemical Hazards: n-Butyl lactate.
    • Clary, J.J., Feron, V.J. and van Velthuijsen, J.A.: Safety assessment of lactate esters. Regul. Toxicol. Pharmacol. 27(2): 88-97, 1998.
    • Pohanish, R.P. (editor): Butyl Lactate. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 416-418.
    • Teeguarden, J.G., et al.: Derivation of a human equivalent concentration for n-butanol using a physiologically based pharmacokinetic model for n-butyl acetate and metabolites n-butanol and n-butyric acid. Toxicol. Sci. 85(1): 429-446, 2005.
  • Date Last Revised: 02/07/2007

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Charcoal Tube (100/50 mg sections, 20/40 mesh)
  • maximum volume: 10 Liters
  • maximum flow rate: 0.2 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • analytical solvent: (95:5) Methylene Chloride:Methanol
  • method reference: OSHA Analytical Method (OSHA PV2080)
  • method classification: Partially Validated

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