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Chemical Sampling Information (CSI)
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General Description

Synonyms: Carboxyethane; Ethanecarboxylic acid; Ethylformic acid; Metacetonic acid; Methyl acetic acid; Propanoic acid

OSHA IMIS Code Number: 2168

Chemical Abstracts Service (CAS) Registry Number: 79-09-4

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: UE5950000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 1848 132

NIOSH Pocket Guide to Chemical Hazards, Propionic acid: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 10 ppm, 30 mg/m3 TWA

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 10 ppm, 30 mg/m3 TWA; 15 ppm, 45 mg/m3 STEL

Health Factors

Potential Symptoms: Irritation of eyes, skin, nose, throat; blurred vision, corneal burns; cough, shortness of breath, sore throat; skin blisters, burns (from contact with liquid); INGES. ACUTE: Abdominal cramps; nausea, vomiting; shock or collapse.

Health Effects: Irritation-Eyes, Nose, Throat, Skin---Marked (HE14)

Affected Organs: Eyes, skin, respiratory system


  1. OSHA does not have a PEL for propionic acid.
  2. Explosive vapor/air mixtures of propionic acid may be formed at temperatures above 54°C.
  3. Propionic acid is listed by the FDA as a synthetic flavoring substance that is generally recognized as safe (GRAS) for its intended use (21 CFR 184.1081)
  4. Normal human volunteers showed a concentration-related reduction in nose-only cumulative inhaled volume at 8.22 and 59.15 ppm propionic acid, whereas anosmic individuals showed a reduction (which was smaller) only at 59.15 ppm. This indicates a significant olfactory component of this respiratory response to nasal irritation from propionic acid.
  5. The formation of tumors in the forestomachs of rats fed propionic acid is thought to not be relevant to human health.
  6. Propionic acidemia is an inherited inborn error of metabolism due to the deficiency of propionyl-CoA carboxylase, and no occupationally related cases have been reported.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Propionic acid.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Propionic acid.
  • Harrison, P.T.: Propionic acid and the phenomenon of rodent forestomach tumorigenesis: a review. Food Chem. Toxicol. 30(4): 333-340, 1992.
  • Henschel, R., Agathos, M. and Breit, R.: Acute irritant contact dermatitis from propionic acid used in animal feed preservation. Contact Dermatitis 40(6): 328, 1999.
  • Lehnert, W., Sperl, W., Suormala, T. and Baumgartner, E.R.: Propionic academia: clinical, biochemical and therapeutic aspects. Experience in 30 patients. Eur. J. Pediatr. 153(7 Suppl. 1): S-68-S80.
  • Pohanish, R.P. (editor): Propionic Acid. In, Sittig’s Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1955-1957.
  • Walker, J.C., Kendal-Reed, M., Hall, S.B., Morgan, W.T., Polyakov, V.V. and Lutz, R.W.: Human responses to propionic acid. II. Quantification of breathing responses and their relationship to perception. Chem. Senses 26(4): 351-358, 2001.

Date Last Revised: 02/27/2007

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Silica Gel Tube (520/260 mesh)
    analytical solvent: (50:50) Acetone: Water
    other analytical solvent: 0.0015 M Borate Buffer for IC analysis
    maximum volume: 18 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Gas Chromatography; GC/FID
    alternate analytical method: Ion Chromatography; IC/Conductivity
    method reference: OSHA (In-House File)
    method classification: Partially Validated

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