Nickel Environmental Exposures
Nickel Environmental Exposures
The primary source of exposure to nickel for most Canadians is food and water. However, nickel is not carcinogenic via ingestion; inhalation exposure is the only pathway linked to cancer.
Nickel is found naturally in soil and in meteorites. It is also released and transported in the environment from windblown dust and volcanic eruptions. Anthropogenic sources include nickel mining and industries that produce alloys or nickel compounds. Oil and coal burning power plants and trash incinerators are additional sources. The type of nickel in the atmosphere depends on the emission source. CAREX Canada estimates that nickel concentrations in outdoor air (moderate data quality) and indoor air (low data quality) do not result in an elevated risk of cancer.
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 nickel in Canada:
NPRI and US Household Products Database
|Search term: ‘nickel and its compounds’|
|Released into Environment||297 t||Petroleum refineries, power generation, nickel|
refineries, mining and foundries (268 facilities)
|Disposed of||214,996 t|
|Sent to off-site recycling||4,385 t|
t = tonne
|US Household Products 2015|
|Search Term||Quantity||Product Type|
|‘nickel’||5||Electrical grease, batteries, and concrete colourant|
This map shows predicted levels of nickel in outdoor air at residential locations by health region in Canada as of 2011. The average (median) concentration of nickel within the health regions measured in outdoor air for 2011 was 0.00066 µg/m3, but concentrations of nickel 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 nickel 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 nickel 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 nickel 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
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
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