Formaldehyde Environmental Exposures

Formaldehyde Environmental Exposures


The biggest sources of environmental formaldehyde are combustion and combustion by-products from power plants, incinerators, refineries, wood stoves, kerosene heaters, cigarettes, photochemical oxidation of hydrocarbons and other formaldehyde precursors, and forest fires.[1,2]


Other sources include vent gas and wastewater from formaldehyde production, vehicle exhaust, and off-gassing from formaldehyde-containing products (e.g., fumigants, soil disinfectants, embalming fluid, leather tanning agents, building material resins, wood products and building materials, and resin-treated fabrics and paper).[1,2]

CAREX Canada estimates that formaldehyde levels in outdoor air do not result in an increased risk of cancer (low data quality). However, these estimates show that formaldehyde levels in indoor air do result in an increased risk (low to moderate data quality).

Historically, the use of urea formaldehyde foam insulation (UFFI) resulted in potentially high concentrations of formaldehyde in homes. UFFI was banned in Canada in 1980.[3]

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 formaldehyde in Canada:

NPRI and US Household Products Database

NPRI 2015[4]
Substance name: ‘Formaldehyde’
Category Quantity Industry
Released into Environment 1,532 t Wood product manufacturing,
meat product manufacturing,
resin and synthetic rubber and fibre manufacturing,
oil and gas extraction
(139 facilities)
Disposed of 119 t
Sent to off-site recycling 18 t
US Household Products 2016[5]
Search Term Quantity Product Type
‘Formaldehyde’ 107 Adhesives, insulations, baby and pet shampoos,
hand soap, body wash, aquatic plant fertilizers
t = tonne


This map shows predicted levels of formaldehyde in outdoor air at residential locations by health region in Canada as of 2011. The average (median) concentration of formaldehyde within the health regions measured in outdoor air for 2011 was 1.772 µg/m3, but concentrations of formaldehyde 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 formaldehyde 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 formaldehyde 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 formaldehyde 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

Our Environmental Approach page outlines the general approach used to calculate lifetime excess cancer risk estimates and includes documentation on our mapping methods.

Data sources and data quality for formaldehyde can be found in the PDF below.

Supplemental data – Formaldehyde [PDF]


1. National Toxicology Program (NTP). 14th Report on Carcinogens for Formaldehyde (2016) (PDF)
2. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Formaldehyde (1999) (PDF)
4. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Facility Search (Substance name: ‘Formaldehyde’)
5. US Household Products Database (HPD). Household Products (Search term: ‘Formaldehyde)

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