Cadmium Environmental Exposures
Cadmium Environmental Exposures
Overview
Food is the major source of cadmium exposure for the general population in Canada (nearly 100% of daily exposure for non-smokers).[1] However, cadmium is not expected to be carcinogenic upon ingestion.
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Cigarette smoking increases the daily intake of cadmium by about 25% (for those smoking 1 pack/day).[1] Forest fires and volcanic eruptions contribute to cadmium levels in the environment; however, the most important natural source is eroding or weathering cadmium-containing rocks.[2]
Cadmium particles can be dispersed over very long distances before settling. Some particles are soluble in water, while others bind tightly to soil.[3] Cadmium may also occur in phosphate deposits, leading to possible environmental contamination when phosphate rock deposits are mined, and when phosphate fertilizers are manufactured and applied.[4] CAREX Canada’s environmental estimates indicate that cadmium levels in outdoor air do not result in higher risks of cancer (moderate data quality). No data on indoor concentrations and exposures was available for cancer risk assessment.
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 cadmium in Canada:
NPRI and US Household Products Database
| NPRI 2015[5] | ||
|---|---|---|
| Substance name: ‘Cadmium and its compounds’ | ||
| Category | Quantity | Industry |
| Released into environment | 9.7 t | Non-ferrous metal (except Aluminum) production and processing, foundries, pulp, paper and paperboard mills (347 facilities) |
| Disposed of | 1,658 t | |
| Sent to off-site recycling | 183 t | |
t = tonne
| US Household Products 2015[6] | ||
|---|---|---|
| Search Term | Quantity | Product Type |
| ‘cadmium’ | 7 | Ceramic glazes(1), gear and motor oils(4), auto wax(1), cement colourant(1) |
| ‘cadmium compounds’ | 1 | Ceramic glazes |
| ‘cadmium sulfide’ | 13 | Pigments |
| ‘cadmium selenide’ | 6 | Pigments |
Mapping
This map shows predicted levels of cadmium in outdoor air at residential locations by health region in Canada as of 2011. The average (median) concentration of cadmium within the health regions measured in outdoor air for 2011 was 0.00020 µg/m3, but concentrations of cadmium 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 cadmium 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 cadmium 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 cadmium 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 cadmium can be found in the PDF below.
Sources
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