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General Description

  • Synonyms: Isovaleral; Isopentaldehyde; 3-Methylbutanal; 3-Methylbutyraldehyde
  • OSHA IMIS Code Number: I201
  • Chemical Abstracts Service (CAS) Registry Number: 590-86-3
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: ES3450000
  • Chemical Description and Physical Properties:
    • molecular weight: 86.13
    • molecular formula: C5H10O
    • boiling point: 90°C
    • melting point: -51°C
    • flash point: -5°C

Health Factors

  • Potential Symptoms: Irritation of eyes, skin, mucous membranes, respiratory system; chest tightness, cough, dyspnea; dizziness, headache, lethargy, anorexia, nausea, vomiting, diarrhea; sweating; tachycardia
  • Health Effects: Irritation-Eyes, Nose, Throat, Skin---Moderate (HE15)
  • Affected Organs: Eyes, skin, respiratory system
  • Notes:
    • OSHA does not have a PEL for isovaleraldehyde. A safe level in the workplace of 10 ppm has been suggested on the basis of an aldehyde NOAEL of 50 ppm in rats.
    • Isovaleraldehyde is listed (as 3-methylbutyraldehyde) by the FDA as a synthetic flavoring substance that is permitted for direct addition to food for human consumption (21 CFR 172.515), and it occurs naturally in various foods and flavorings (e.g., coffee, cheese, corn tortilla chips, and orange, lemon and eucalyptus oils).
    • Its level in plasma can be increased by oral feeding of the amino acid leucine.
    • In sensory irritation studies with mice, the RD50 (concentration decreasing respiratory rate in 10 minutes) for isovaleraldehyde was 757-1008 ppm.
    • Inhalation of isovaleraldehyde at 6176 mg/m3 for 10 hours was lethal in 3/5 mice, 5/20 guinea pigs, and 0/5 rabbits.
  • Literature Basis:
    • Buttery, R.G. and Ling, L.C.: Additional studies on flavor components of corn tortilla chips. J. Agri. Food Chem. 46(7): 2764-2769, 1998.
    • Ford, R.A., Letizia, C. and Api, A.M.: 3-Methylbutyraldehyde. Food Chem. Toxicol. 26(4): 379-380, 1988.
    • Marshall, A.W., DeSouza, M. and Morgan, M.Y.: Plasma 3-methylbutanal in man and its relationship to hepatic encephalopathy. Clin. Physiol. 5(1): 53-62, 1985.
    • No authors listed: SIDS Initial Assessment Report for SIAM 10, 3-Methylbutanal (and) IUCLID Data Set, isovaleraldehyde. UNEP Publications (2002).
    • Smit, B.A., Engels, W.J., Wouters, J.T. and Smit, G.: Diversity of L-leucine catabolism in various microorganisms involved in dairy fermentations, and identification of the rate-controlling step in the formation of the potent flavour component 3-methylbutanal. Appl. Microbiol. Biotechnol. 64(3): 396-402, 2004.
    • Steinhagen, W.H. and Barrow, C.S.: Sensory irritation structure-activity study of inhaled aldehydes in B6C3F1 and Swiss-Webster mice. Toxicol. Appl. Pharmacol. 72(3): 495-503, 1984.
  • Date Last Revised: 3/07/2007

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • coated XAD-2 Tube (150/75 mg sections, 20/60 mesh); coating is 10% (w/w) 2-(Hydroxymethyl)piperidine
  • analytical solvent: Toluene
  • maximum volume: 5 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/NPD with GC/MS identification
  • method reference: OSHA Modified NIOSH Analytical Method (NIOSH 2539 (PDF))
  • method classification: Partially Validated
  • note: OSHA modification is use of GC/NPD in place of GC/FID. This is a screening method and is not quantitative.
  • silica gel tube coated with acidified 2,4-dinitro-phenyl hydrazine
  • analytical solvent: Acetonitrile
  • maximum volume: 15 Liters
  • maximum flow rate: 1.5 L/min
  • current analytical method: High Performance Liquid Chromatography, HPLC/UV
  • method reference: NIOSH Analytical Method (NIOSH 2018 (PDF))
  • method classification: Partially Validated

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