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Crotonaldehyde – Focus on specific chemicals of interest

Crotonaldehyde is a colorless or white liquid with a suffocating odor which turns a pale-yellow color on contact with air. It is used as an intermediate for production of sorbic acid and formerly was used in manufacture of n-butyl alcohol. It is formed during fossil fuel combustion.

Other names for crotonaldehyde are:

  • 2-Butenal
  • β-Methyl Acrolein
  • Propylene Aldehyde
  • Crotonic Aldehyde

It is considered to be a Class 1B Flammable Liquid.

Let’s understand the risk it presents.

A little bit of chemistry

CAS 42170-30-3; Molecular Formula CH3CH=CHCHO

Crotonaldehyde has incompatibilities or can react with caustics, ammonia, concentrated oxidizing substances, nitric acid, and amines.

Polymerization may occur at high temperatures, such as in a fire.

It is a colorless or white liquid with a suffocating odor which turns a pale-yellow color on contact with air.

Eye/skin irritant/corrosive / skin absorption potential

Crotonaldehyde is an irritant of the eyes, skin, and respiratory tract.

Eight cases of industrial injury from crotonaldehyde exposure were reported. The severity of corneal injuries was not reported, but healing was said to occur within 48 hours. No details on the treatment were available.

The European Chemical Agency (ECHA) recommends to label it with the following risk phrases:

Risk phrase Meaning
H225 Highly flammable liquid and vapour
H301 Toxic if swallowed
H311 Toxic in contact with skin
H315 Causes skin irritation
H318 Causes serious eye damage
H330 Fatal if inhaled
H335 May cause respiratory irritation
H341 Suspected of causing genetic defects
H373 May cause damage to organs through prolonged or repeated exposure
H400 Very toxic to aquatic life

What to do in case of an exposure to crotonaldehyde

The above data suggest that an amphoteric washing solution such as Diphoterine® solution would most likely be of use with acute exposures to prevent or mitigate eye/skin injuries. In case of exposure to crotonaldehyde, emergency washing with Diphoterine® solution is recommended in order to limit the induced injuries. (lien vers la page diphotérine)

Chronic effects/carcinogenicity

In experimental animal studies, rats did not survive inhalation exposure to 1,650 ppm for 10 minutes and major lung damage was found. Similar findings occurred in rats when there was exposure to 1,500 ppm for 30 minutes or to 100 ppm for 4 hours.

In 113 weeks drinking water studies in rats, some hepatocellular abnormalities occurred and there were some cancers found.

Crotonaldehyde has produced conflicting effects in various genetic assays.

The IARC (International Agency for Research on Cancer) has concluded that there is inadequate evidence for the potential carcinogenicity of crotonaldehyde in human and experimental animals. It is not classifiable with regards to its potential carcinogenicity to humans.

Regulatory/advisories issues

  • US OSHA: The US OSHA Permissible Exposure Limit (PEL) is 2 ppm (6 mg/m3).
  • US NIOSH: Immediately Dangerous to Life or Health (IDLH) value is 50 ppm. The NIOSH recommended exposure limit (REL) Time Weighted Average (TWA) is 2 ppm (6 mg/m3).
  • US ACGIH: TLV-TWA 2 ppm (5.7 mg/m3)

References consulted

Anon. Crotonaldehyde. IARC Monogr Eval Carcinog Risks Hum. 1995; 63:373-391.
ECHA: https://echa.europa.eu/information-on-chemicals/cl-inventory-database, accessed August 25, 2014.
Eder E, Schuler D, Budiwan. Cancer risk assessment for crotonaldehyde and 2-hexenal: an approach. IARC Sci Publ 1999; 150:219-232.
Eder E, Budiwan, Schuler D. Crotonaldehyde: a carcinogenic and mutagenic air, water and food pollutant. Cert Eur J Public Health 1996; 4(Suppl):21-22.
Hathaway GH, Proctor NH (eds). Crotonaldehyde, in: Proctor and Hughes’ Chemical Hazards of the Workplace, 5th ed. Wiley Interscience, Hoboken, NJ, 2004, pp. 187-188.
HSDB. Crotonaldehyde in: Hazardous Substances Data Bank, National Library of Medicine, Bethesda, MD, USA. https://www.nlm.nih.gov (Toxnet), accessed July 28, 2014.
Huang JF, Zhu DM, Zhong M. Acute respiratory distress syndrome due to a high-concentration mixture of ethenone and crotonaldehyde. Toxicol Ind Health 2013; Feb 28 (E-pub ahead of print.).
Jha AM, Singh AC, Sinha U, Kumar M. Genotoxicity of crotonaldehyde in the bone marrow and germ cells of laboratory mice. Mutat Res 2007; 632(1-2):69-77.
INRS: No Toxicological Sheet found. INRS Toxicological Sheets, accessed August 25, 2014.
Islam UL et al. Genotoxicity and immunogenicity of crotonaldehyde in modified human DNA. Int J Biol Macrobiol. 2014; 65:471-778.
Liu XY, Yang ZH, Pan XJ, Xhu MX, Xie JB. Crotonaldehyde induces oxidative stress and caspace-dependent apoptosis in human bronchial epithelial cells. Toxicol Lett 2010; 195(1):90-98.
Neudecker T, Lutz D, Eder E, Henschler D. Crotonaldehyde is mutagenic in a modified Salmonella typhimurium mutagenicity testing system. Mutat Res 1981; 91(1):27-31.
NIOSH: Crotonaldehyde, in: NIOSH Pocket Guide to Chemical Hazards, Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Health and Safety, DHHS (NIOSH) Publication No. 2005-149, Cincinnati, OH, USA, 2007, p. 80.
Salgado MS, Modenero E, Villanueva F, Martin P, Tapia A, Cabañas B. Night-time atmospheric fate of acrolein and crotonaldehyde. Environ Sci Technol 2008; 42(7):2393-2400.
Stein, S, Lao Y, Lang IY, Hecht SS, Moriva M. Genotoxicity of acetaldehyde and crotonaldehyde-induced 1,N2-propanodioxy guanosine DNA adducts in human cells. Mutat Res 2006; 608(1):1-7.

Alan H. Hall, M.D. President and Chief Medical Toxicologist
Toxicology Consulting and Medical Translating Services, Inc.
Clinical Assistant Professor
Colorado School of Public Health
University of Colorado-Denver
Denver, Colorado, USA