Acetaldehyde
Full Profile
General Information
Acetaldehyde is a colourless and volatile liquid with a sharp and fruity odour.[2] Acetaldehyde has widespread industrial use as a chemical intermediate.[3] It is a metabolite of sugars and ethanol in humans,[3] is found naturally in the environment, and is a product of biomass combustion.[4] Acetaldehyde may also be referred to as ethanal or acetic aldehyde. There are numerous other synonyms and product names; see the HSDB for more information.[5]
Acetaldehyde has been classified by IARC as Group 2B, possibly carcinogenic to humans, based on evidence in animals.[3] Acetaldehyde is a respiratory tract carcinogen in experimental animals, especially of the nasal mucosa in rats and of the larynx in hamsters.[3]
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.[3] 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 than those who didn't develop cancer.[3] Further study is required to establish a causal relationship.
Acetaldehyde can cause respiratory and eye irritation and in severe cases, lung edema.[5] It also exacerbates the effects of alcohol and is a central nervous system depressant.[5]
Acetaldehyde has been ranked by CAREX Canada for both the occupational and environmental settings as Group A (immediate high priority). Prioritization was based on the carcinogenicity and other toxic properties of acetaldehyde, the prevalence of exposure in Canada, and the feasibility of assessing exposure.
Regulations and Guidelines
Occupational Exposure Limits (OEL)
| Canadian Jurisdictions | OEL (ppm) |
|---|---|
| Canada Labour Code | 25 [c] |
| BC, AB, SK, MB, ON, QC, NL, PE, NB, NS | 25 [c] |
| NT, NU, YT | 100 150 [stel] |
| Other Jurisdiction | OEL (ppm) |
| ACGIH 2011 TLV | 25 [c] |
Canadian Environmental Guidelines
| Jurisdiction | Limit | Year |
|---|---|---|
| Residential Indoor Air Quality | 5 ppm | 1987[7] |
Acetaldehyde was not included in other Canadian government environmental guidelines reviewed.[6,13,14]
Canadian Agencies/Organizations
| Agency | Designation/Position | Year |
|---|---|---|
| Health Canada | DSL – low priority substance (already risk managed) | 2006[8] |
| CEPA | Schedule 1, paragraphs 'b' and 'c' | 1999 |
Main Uses
Acetaldehyde is used primarily as a chemical intermediate, especially in the production of acetic acid, pyridine, and butylene glycol.[2]
Acetaldehyde is also used as a food additive for flavouring.[2] In the US, it falls under the Food and Drug Administration's definition of "generally recognized as safe" (GRAS),[10] although some researchers have been calling for a re-evaluation of this classification.[11] Acetaldehyde is also used in the production of some fragrances and flavours, pesticides, dyes, synthetic rubber, disinfectants, lacquers and varnishes, photographic chemicals, and room air deodorizers.[4]
Canadian Production and Trade
According to TradeMap, there were no reported imports or exports of acetaldehyde in Canada from 2001 to 2007.[16] Camford services did report that 62,250 tonnes were imported from the US in 2002, the highest amount reported since 1988.[12]
Until 2002, when production was phased out, one Canadian company produced 1,500 tonnes of acetaldehyde per year. It was used mainly in alkyd resins and pentaerythritol production.[12]
Production and Trade
| Activity | Quantity | Year |
|---|---|---|
| Canadian Production | 0.5 kt | 2001[12] |
| Domestic consumption | 60 t | 2005 (forecasted)[12] |
Occupational Exposures
Inhalation is the most important route of occupational exposure.[2] The main occupational exposures occur in acetic acid production workers, as well as those involved in the dyestuff, plastics, and synthetic rubber industries.[2] In Canada, workers in pentaerythritol production may be exposed.[4]
Workers involved in diacetyl production, a substance used for food flavourings, especially in microwave popcorn, can also be exposed to acetaldehyde; recent studies from the Netherlands[16] and the US[17] have measured acetaldehyde exposure during production of diacetyl.
Because acetaldehyde is also a combustion product, potential for exposure in the petroleum, transportation, waste burning, firefighting, and wood products industries is possible as well.[4]
Environmental Exposures
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).[2]
The largest source of exposure to the general population is technically via the consumption of alcohol, where it is produced during the metabolism of alcohol. In the environment, inhalation exposures are the most important.[2]
The most important 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).[4]
A Canadian study in PEI measuring indoor air concentrations of several compounds, including acetaldehyde, found that smoking was a significant source of acetaldehyde in homes; especially when air exchange rates were lower.[16]
Acetaldehyde, along with several other volatile organic compounds, is also released from common building materials such as engineered wood products typically used in manufactured homes. This creates potential for exposure to inhabitants.[17]
A recent review of acetaldehyde toxicity from the government of California lists several studies from the last 15-20 years where measurements of acetaldehyde were taken in residences as well as portable classrooms.[18] According to this organization, indoor measurements of acetaldehyde usually greatly exceed outdoor measurements.
Searches of environmental and consumer product databases yielded the following results on current potential for exposure to acetaldehyde in Canada:
NPRI and US Household Products Database
| NPRI 2009[19] | ||
|---|---|---|
| Search term: 'acetaldehyde' | ||
| Category | Quantity | Industry |
| Released into Environment | 878 t | Oriented strand board (OSB) production, chemical manufacture, sawmills, pulp and paper industry, and in a few bakeries (86 companies) |
| Disposed of | 1 t | |
| Sent to off-site recycling | None | |
| US Household Products 2010[20] | ||
|---|---|---|
| Results: 4 products | ||
| Search Term | Quantity | Product Type |
| 'acetaldehyde' | 4 | Hobby glues (3) and powdered roof leveler (1) |
Sources
- Wikimedia Commons Photo: Acetaldehyde
- NTP 12th report on carcinogens for Acetaldehyde (PDF)
- IARC monograph summary, Volume 71, 1999 (PDF)
- Priority Substances List assessment report (CEPA) for Acetaldehyde (2000) (PDF)
- Hazardous Substances Database entry for Acetaldehyde (Search term: 'acetaldehyde')
- Guidelines for Canadian Drinking Water (2010)
- Exposure Guidelines for Residential Indoor Air Quality (1987) (PDF)
- Health Canada's Prioritization of the DSL
- CEPA List of Toxic Substances
- Electronic Code of Federal Regulations: Substances Generally Recognized as Safe
- CPI Product Profiles, Camford Information Services: Acetaldehyde (2003)
- Food Additive Dictionary, Health Canada
- Health Canada (2010) Cosmetic Ingredient Hotlist
- TradeMap (Free subscription required)
- Van Rooy et al. 'A cross sectional study on lung function and respiratory symptoms among chemical workers producing diacetyl for food flavourings.' Occup. Environ. Med, Accepted 1 August 2008, epub available as of Oct, 2008.
- Sahakian et al. 'Asthma arising in flavoring-exposed food production workers.' Int. J. Occ. Med. Environ. Health 2008;21(2):173 – 177
- Hodgson et al. (2002) 'Sources of formaldehyde, other aldehydes and terpenes in a new manufactured house.' Indoor Air 12(4): 235–242
- Acetaldehyde Reference Exposure Levels, September 2008. Office of Environmental Health Hazard Assessment, California (PDF)
- The National Pollutant Release Inventory
- Household Products Database (US)
