Acetaldehyde Environmental Exposures
Acetaldehyde Environmental Exposures
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).[1,2]
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.[3,4] 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.
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||668 t||Pulp, paper and paperboard mills,
veneer, plywood manufacture,
|Disposed of||0.024 t|
|Sent to off-site recycling||None|
t = tonne
|US Household Products 2016|
|Results: 13 products|
|Search Term||Quantity||Product Type|
|‘Acetaldehyde’||13||Arts & crafts adhesives (5), home adhesives (5),
landscape adhesive(1); powdered roof leveler (1);
automotive products (1)
This map shows predicted levels of acetaldehyde in outdoor air at residential locations by health region in Canada as of 2011. The average (median) concentration of acetaldehyde within the health regions measured in outdoor air for 2011 was 1.294 µg/m3, but concentrations of acetaldehyde can be higher or lower than average in many locations. Concentrations should be compared to the applicable jurisdictional guidelines and standards for ambient air quality based on chronic, carcinogenic effects (or non-carcinogenic effects, if cancer is not the point of interest).
Predicted annual average acetaldehyde concentrations in outdoor air at residential locations by health region, 2011
*Measured at the National Air Pollution Surveillance (NAPS) monitors in 2011
Cancer Risk Estimates
Potential lifetime excess cancer risk (LECR) is an indicator of Canadians’ exposure to known or suspected carcinogens in the environment. When potential LECR is more than 1 per million in a single pathway, a more detailed risk assessment may be useful for confirming the need to reduce individual exposure. If measured levels of acetaldehyde in relevant exposure pathways (outdoor air and indoor air) decrease, the risk will also decrease.
Potential LECR is calculated by multiplying lifetime average daily intake (the amount inhaled or ingested) by a cancer potency factor or unit risk factor. More than one cancer potency factor may be available, because agencies interpret the underlying health studies differently, or use a more precautionary approach. Our results use cancer potency factors from Health Canada, the US Environmental Protection Agency (US EPA), and/or the California Office of Environmental Health Hazard Assessment (OEHHA).
The calculated lifetime daily intake and LECR results for acetaldehyde are provided in the tables below. For more information on supporting data and sources, click on the Methods and Data tab below.
Calculated Lifetime Daily Intake
Lifetime Excess Cancer Risk (per million people)
*LECR based on average intake x cancer potency factor from each agency
Compare substances: Canadian Potential Lifetime Excess Cancer Risk, 2011
The data in this table are based on average intake and Health Canada’s cancer potency factor, assuming no change in measured levels. When Health Canada values are not available, United States Environmental Protection Agency values are used.
Click the second tab to view LECR data.
**Exposure not applicable: For indicated pathways, substance not present, not carcinogenic, or exposure is negligible
**Gap in data: No cancer potency factor or unit risk factor, or no data available
IARC Group 1 = Carcinogenic to humans, IARC Group 2A = Probably carcinogenic to humans, IARC Group 2B = Possibly carcinogenic to humans
NOTE: Chromium (hexavalent) estimates assume that 5% of total chromium measured in outdoor air is hexavalent and 8% total chromium measured in indoor dust is hexavalent.
Potential LECR assumes exposure occurs at the same level, 24 hours per day, for 70 years. This is rarely true for any single individual, but using a standard set of assumptions allows us to provide a relative ranking for known and suspected carcinogens across different exposure routes. While ongoing research continually provides new evidence about cancer potency and whether there is a safe threshold of exposure, our approach assumes there are no safe exposure levels.
Methods and Data
Subscribe to our newsletters
The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.