Industrial Chemicals– Possible Carcinogen (IARC 2B)
CAS No. 75-07-0
Photo: Wikimedia Commons
IARC Monograph Vol. 71, 1999 (Group 2B)
Acetaldehyde is a colourless and volatile liquid with a sharp and fruity odour. It is widely used industrially as a chemical intermediate. Acetaldehyde is also a metabolite of sugars and ethanol in humans, is found naturally in the environment, and is a product of biomass combustion. It may also be referred to as ethanal or acetic aldehyde. There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.
Acetaldehyde has been classified by the International Agency for Research on Cancer (IARC) as Group 2B, possibly carcinogenic to humans, based on evidence in animals. Acetaldehyde is a respiratory tract carcinogen in experimental animals, especially of the nasal mucosa in rats and of the larynx in hamsters.
There is inadequate evidence for the carcinogenicity of acetaldehyde in humans. One small study of workers manufacturing several types of aldehydes found increased risk of bronchial tumours, but workers were exposed to many other chemicals in addition to acetaldehyde. Three other studies on the carcinogenicity of alcoholic beverages found that people who developed cancer after heavy alcohol use had genetic differences and higher concentrations of acetaldehyde in their blood compared to those who didn't develop cancer. Further study is required to establish a causal relationship.
Acetaldehyde can cause respiratory and eye irritation and in severe cases, lung edema. It also exacerbates the effects of alcohol and is a central nervous system depressant.
Agreement Respecting the Great Lakes Basin Ecosystem
Listed as a "Hazardous Polluting Substance"
National Classification System for Contaminated Sites
Rank = "High hazard", potential human carcinogen
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act
Acetaldehyde was not included in other Canadian government chemical listings reviewed.
Acetaldehyde is used primarily as a chemical intermediate, especially in producing acetic acid, pyridine, and butylene glycol.
Acetaldehyde is also used as a food additive for flavouring. In the US, it falls under the Food and Drug Administration's definition of "generally recognized as safe" (GRAS), although some researchers have been calling for a re-evaluation of this classification. Acetaldehyde is also used to produce some fragrances and flavours, pesticides, dyes, synthetic rubber, disinfectants, lacquers and varnishes, photographic chemicals, and room air deodorizers. Acetaldehyde has also been used in hydraulic fracturing fluids.
Canadian Production and Trade
According to TradeMap, there were no reported imports or exports of acetaldehyde in Canada from 2001 to 2007. Camford services reported that 62,250 tonnes of acetaldehyde were imported from the US in 2002, the highest amount reported since 1988.
Until 2002, when production was phased out, one Canadian company produced 1,500 tonnes of acetaldehyde per year. It was used mainly to produce alkyd resins and pentaerythritol.
Production and Trade
t = tonne
kt = kilotonne
Inhalation is the most important route of occupational exposure. CAREX Canada estimates that approximately 8,600 Canadians are exposed to acetaldehyde in the workplace. By industry, the largest exposed groups are plastic products manufacturing, food manufacturing, and farming. By occupation, the greatest exposures occur among plastic machine operators, followed by farmers, farm managers, and rubber and plastic manufacturing labourers.
In food manufacturing, workers are exposed to acetaldehyde during diacetyl production. Diacetyl is a substance used for food flavouring, especially in microwave popcorn. Recent studies from the Netherlands and the US have measured acetaldehyde exposure during production of diacetyl.
Because acetaldehyde is also a combustion product, exposure in the petroleum, transportation, waste burning, fire fighting, and wood products industries is also possible.
In the environment, inhalation is the most important route of exposures to acetaldehyde. A significant source of inhalation exposure to the general population is biomass combustion, which is typically higher in urban areas (from vehicles, industrial burning, forest fires, and cigarette smoke).[2,4] CAREX Canada estimates that the acetaldehyde levels in outdoor air do not result in higher risk of cancer at a population level (low data quality). However, results show that acetaldehyde levels in indoor air do result in an increased risk of cancer (moderate data quality).
Canadian studies in Prince Edward Island and Saskatchewan measured indoor air concentrations of several compounds, including acetaldehyde, and found that smoking was a significant source of acetaldehyde in homes. This was the case especially when air exchange rates were lower.[22,25] Cooking with oil was also associated with increased levels of acetaldehyde indoors.
Acetaldehyde, along with several other volatile organic compounds, is released from common building materials such as engineered wood products typically used in manufactured homes. This creates potential for exposure to inhabitants of these homes.
A review of acetaldehyde toxicity from the Government of California published in 2008 lists several studies from the last 15-20 years where measurements of acetaldehyde were taken in residences as well as portable classrooms. According to this review, indoor measurements of acetaldehyde usually greatly exceed outdoor measurements.
Acetaldehyde is a metabolic intermediate in humans and other organisms. It is also found naturally in some foods in trace amounts, especially after cooking, ripening of fruit, or fermentation (i.e. in beer and wine). The largest source of exposure to acetaldehyde in the general population is technically via alcohol consumption, where it is produced during alcohol metabolism. However, acetaldehyde is not carcinogenic via ingestion.
For more information, see CAREX Canada's environmental exposure estimates for acetaldehyde. Searches of environmental and consumer product databases yielded the following results on current potential for exposure to acetaldehyde in Canada:
Searches of Environment Canada's National Pollutant Release Inventory (NPRI) and the US Household Products Database yielded the following results on current potential for exposure to acetaldehyde in Canada:
NPRI and US Household Products Database
Substance name: 'Acetaldehyde'
Released into Environment
Pulp, paper and paperboard mills, veneer, plywood manufacture, chemical manufacturing (61 facilities)
Sent to off-site recycling
US Household Products 2016
Results: 13 products
Arts & crafts adhesives (5), home adhesives (5), landscape adhesive(1); powdered roof leveler (1); automotive products (1)
t = tonne
Our team has performed a detailed scan of exposure control resources and assembled a compilation of key publications and resources. These are organized by type of exposure (environmental or occupational) and by specificity (general or carcinogen-specific). Please visit our Exposures Reduction Resources page to view.
We also recommend exploring the Prevention Policies Directory, a freely-accessible online tool offering information on policies related to cancer and chronic disease prevention. Providing summaries of the policies and direct access to the policy documents, the Directory allows users to search by carcinogen, risk factor, jurisdiction, geographical location, and document type. Click here to learn more about policies specific to acetaldehyde on the Directory. For questions about this resource, please contact a member of the Prevention Team at the Canadian Partnership Against Cancer at firstname.lastname@example.org.