Cadmium (Cd) is a soft, silver-white or blue, lustrous metal typically found in mineral deposits with lead, zinc and copper. Cadmium is normally found in the forms of cadmium oxide, cadmium chloride, or cadmium sulfate/sulfide. Cadmium most frequently occurs in zinc deposits as cadmium sulfide and is a by- product of zinc concentrates, making its production dependent on the demand for zinc.
Cadmium and its compounds have been classified by IARC as Group 1, carcinogenic to humans, on the basis of sufficient evidence of carcinogenicity in humans and animals. A recent review of Class 1 carcinogens reaffirmed the classification for cadmium and its compounds. Epidemiological studies reviewed by IARC showed consistent evidence that cadmium workers were at increased risk of lung cancer. Other studies have suggested elevated risks of prostate, kidney and bladder cancers.[3,18]
Acute inhalation of cadmium at high concentrations affects the lungs, causing severe damage and possibly death. Chronic inhalation at low concentrations affects the kidneys, resulting in cadmium accumulation and possible kidney disease. Chronic ingestion of cadmium at low levels can result in kidney damage and bone effects.
Schedule 1, paragraphs A and C for ‘inorganic cadmium’
The most common use of cadmium is in battery production, specifically as cadmium hydroxide, one of two electrode materials used in rechargeable nickel-cadmium (Ni-Cd) batteries. Global use of cadmium in 2005 was distributed as follows: batteries, 81%; pigments, 10%; coatings, 6%; stabilizers, 2% and alloys and minor uses, 1%.
Cadmium sulphide is used as a pigment in plastics, ceramics, glasses, enamels and artists colours (yellows and reds). Cadmium salts are used as stabilizers in polyvinyl chloride (PVC) plastics, and also in coatings for electronics, steel and aluminum for corrosion resistance. Other minor uses for cadmium include alloys, solar cells and semiconductors. Other than for batteries, production and use of cadmium has decreased significantly over the past 50 years.
Approximately 10-15% of cadmium produced in the western world is from recycled products. There are 9 recycling facilities in the US, Japan and Europe capable of recycling industrial and commercial Ni-Cd batteries and manufacturing scrap.
Production and Trade
In 2006, Canada was the fifth largest producer of cadmium, producing 2,094 tonnes of refined cadmium - an increase of 21% from the previous year.
Cadmium is mined as a by-product in New Brunswick, Quebec and Ontario and refined at all four Canadian zinc smelters (located in Valleyfield, Quebec; Trail, BC; Timmins, Ontario; and Flin Flon, Manitoba). The majority of Canada’s exports are sent to Belgium, Japan, China, and the Netherlands.
Export: Mainly to Belgium, China
1673 t of ‘cadmium and articles thereof’
Import: Mainly from Brazil, US
89 t of 'cadmium and articles thereof'
Inhalation is the main route of occupational exposure to cadmium. CAREX Canada estimates that approximately 31, 000 Canadians are exposed to cadmium at work, with most of these exposures occurring in the moderate exposure category.
In Canada, the industry with the largest number of workers occupationally exposed to cadmium is sawmill and wood preservation, where workers are exposed through sawfiling or working near sawfiling areas. Other industries with large numbers of workers exposed to cadmium include automotive repair, and commercial and industrial machinery repair.
When exposure is examined by occupation, the largest occupational group exposed is welders. Welders are employed in diverse industries, and this exposure can occur when welding stainless steel containing cadmium or cadmium-coated surfaces. Other important exposed occupational groups include automotive service technicians and sawfilers.
For more information, see the CAREX Canada occupational exposure estimates for cadmium.
Food is the major source of cadmium exposure to the general population in Canada (nearly 100% of daily exposure for non-smokers). However, cadmium is not expected to be carcinogenic upon ingestion. Cigarette smoking increases the daily intake of cadmium by about 25% (for those smoking 1 pack/day).
Forest fires and volcanic eruptions contribute to the amount of cadmium in the environment; however, the most important natural source is erosion or weathering of cadmium-containing rocks. Cadmium particles can be dispersed very long distances before settling. Some particles are soluble in water, while others bind tightly to soil. Cadmium may also occur in phosphate deposits, leading to possible environmental contamination during mining of phosphate rock deposits, and manufacturing and application of phosphate fertilizers. CAREX Canada’s environmental estimates indicate that cadmium levels in outdoor air are not resulting in higher risks of cancer (moderate data quality). No data was available on cadmium indoor concentrations and exposures for cancer risk assessment.
For more information, see the CAREX Canada environmental exposure estimates for cadmium. Searches of environmental and consumer product databases yielded the following results on current potential for exposure to cadmium in Canada:
NPRI and US Household Products Database
Search term: ‘cadmium and its compounds’
Released into Environment
Mining, smelters, pulp and paper, power generation, water treatment and oil refineries. (375 companies)
Sent to off-site recycling
US Household Products 2013
Ceramic glazes, gear and motor oils, auto wax, cement colorant
Pigments, ceramic glazes
t = tonne
Our team has performed a detailed scan of exposure control resources and assembled a compilation of key publications and resources. These are organized by type of exposure (environmental or occupational) and by specificity (general or carcinogen-specific). Please visit our Exposures Reduction Resources page to view.
We also recommend exploring the Prevention Policies Directory, a freely-accessible online tool offering information on policies related to cancer and chronic disease prevention. Providing summaries of the policies and direct access to the policy documents, the Directory allows users to search by carcinogen, risk factor, jurisdiction, geographical location, and document type. To learn more about policies specific to cadmium on the Directory, click here. For questions about this resource, please contact Michelle Halligan, from the prevention team at the Canadian Partnership Against Cancer.