The National Pollutants Release Inventory: cadmium and its compounds

Background

Each year, the Government of Canada requires businesses, institutions and facilities across Canada to report their pollutant releases and disposals to the National Pollutant Release Inventory (NPRI). These facilities must report the pollutants they release and dispose of in different environmental compartments (i.e., in the air, water and land). The information collected by the NPRI is public, and allows the Government of Canada to establish environmental priorities and assess the environmental performance of these substances. Canadians can use this information to learn more about pollution in their living environment.

Cadmium and its compounds are part of the NPRI’s Substance Overview Series. This document presents a detailed analysis of the quantities of cadmium reported to the NPRI. It also summarizes the impacts that cadmium and its compounds can have on environmental and human health, as well as the measures taken by reporting facilities to mitigate them.

Cadmium and its compounds

Pure cadmium (Cd) is a silvery-white metal with lustrous blue reflections. It is possible to find cadmium in several forms; some of these compounds are insoluble in water (e.g., elemental or unwrought cadmium) and others can be dissolved under conditions of oxidation or high acidity. Cadmium is used to make batteries, metallic coatings, solar cells and plastic stabilizers. Cadmium enters the environment through mining operations and the action of wind and rain. Forest fires and volcanoes also release some cadmium into the air.

In this overview, we will discuss cadmium and its compounds as most of these compounds are obtained as a by-product of zinc refining and are present in lead and copper ores. Cadmium compounds are mainly found in the form of chloride, oxide, sulfate or sulphide.

Consult the priority substances list Assessment Report for more information on cadmium and its compounds.

Effects on human health

In general, Canadians can be exposed to cadmium and its compounds in the environment from several sources. Some of the cadmium compounds can be absorbed through inhalation and ingestion. The main effects in humans are cases of skin and eye irritation following significant intoxication at high concentrations.

Environment and Climate Change Canada, as well as Health Canada, have classified cadmium and its compounds in the group of substances probably carcinogenic to humans by inhalation (Environment Canada and Health Canada, 1994). In 2012, according to the International Agency for Research on Cancer (only available in French), cadmium and its compounds were classified as carcinogenic to humans. Although cadmium and its compounds are carcinogenic, only a small proportion of the population is exposed to cadmium in the workplace. It is challenging to interpret the results of these studies because workers are simultaneously exposed to other types of heavy metals, such as lead, zinc and nickel, which are associated with the same cancers as cadmium and its compounds, particularly lung cancer.

Oral ingestion of high doses of cadmium can cause severe gastrointestinal irritation and kidney damage. The kidneys are critical organs since the first harmful effects appear there following oral or inhalation exposure.

Environmental effects

Natural processes contributing to the presence of cadmium in the atmosphere are primarily wind transport of soil particles, forest fires, volcanic emissions and bedrock weathering. Among these natural sources, weathering and erosion of cadmium-bearing rocks^{Footnote 1}  are the most significant source. However, the largest quantities of cadmium in the environment come from anthropogenic sources, i.e., from human activities. For example, the smelting of metals with properties similar to those of cadmium and its compounds and the burning of fossil fuels are two key contributors to cadmium releases into the atmosphere. Electricity generation, heating, transportation, solid waste disposal and sewage sludge application are other anthropogenic sources of cadmium in the environment.

Cadmium oxide in the atmosphere is primarily in fine particulate form. Cadmium’s various compounds do not react with ozone and thus do not contribute to climate change (Environment Canada, 2007). However, climate change can lead to air quality issues due to increased global temperatures.

According to Health Canada studies, inorganic cadmium compounds are not entering the environment in a quantity, concentration, or under conditions that constitute a danger to the environment on which human life depends.

Reporting facilities

In 2020, 373 facilities reported the use of cadmium and its compounds to the NPRI. Various industrial sectors reported releases, disposals and transfers for recycling for this substance. Metal ore mining (123 facilities), waste treatment and disposal (88 facilities), pulp and paper (52 facilities) and oil and gas (28 facilities) were the main sectors to report the use of cadmium and its compounds. Other industrial sectors reported having released small quantities of cadmium and its compounds; these sectors have been grouped into the “All other sectors” category (54 facilities).

In 2020, the provinces with the highest number of facilities reporting the use of cadmium and its compounds to the NPRI were Ontario (118), followed by Québec (77), Alberta (64) and British Columbia (54). The table below shows that in Ontario and Québec the metal ore mining sector accounted for the largest number of facilities reporting the use of cadmium and its compounds (48 and 30 facilities, respectively). In Alberta and British Columbia, waste processing and disposal was the sector with the largest number of facilities reporting cadmium and its compounds (23 and 11 facilities, respectively).

*in 2020, no facilities from the Yukon submitted a report.

Locations of facilities reporting releases of cadmium and its compounds to the NPRI in 2020, by sector

Total releases

In 2020, facilities reported 5.48 tonnes of cadmium and its compounds to air, water and land combined. Of these releases, the metal ore mining sector was the largest quantity (51%, or 2.8 tonnes), followed by the waste treatment and disposal sector (23%, or 1.25 tonnes), and the pulp and paper sector (19%, or 1.03 tonnes).

In total, 90 of the 123 (73%) reporting facilities from the metal ore mining sector were mines and quarries. More specifically, 41% of releases came from gold and silver mining, and 14% of releases came from copper and nickel.

The circular diagram below (Figure 1) shows the distribution of all releases for certain sectors. The chemicals sector (not represented) was less than one per cent (0.008 tonnes).

In 2020, Ontario was the province with the highest reported releases of cadmium and its compounds to air, water and land, representing 36% (2 tonnes) of releases, followed by Québec, which accounted for 33% (1.8 tonnes) of releases to all the environmental compartments. Figure 2 below shows the breakdown of reported releases by province, for the same year, i.e., 2020.

Total releases of cadmium and its compounds reported to the NPRI across Canada in 2020.

Overall, the total releases of cadmium and its compounds decreased between 2010 and 2020. Figure 3 below shows that, on average, releases have gradually decreased over the past ten years. Between 2014 and 2020, facilities in the metal ore mining sector, including mines and quarries, as well as the pulp and paper industry, released smaller quantities to water, air and land.

According to NPRI trends, the presence of cadmium and its compounds has also decreased in the wastewater treatment sector. This trend is primarily attributed to a decrease in releases of wastewater effluent because of source reductions.

See the Releases of harmful substances to water report to learn more about releases of cadmium in water.

Total disposals and transfers for treatment and recycling

In 2020, 2,773 tonnes of cadmium and its compounds were reported to the NPRI as disposals or transfers for treatment and recycling. The sectors reporting the largest quantities of disposals or transfers were the metal ore mining sector with 50% (1,380 tonne) of disposals, and the waste treatment and disposal sector (49% or 1,339 tonnes).The remaining sectors reported 1% or 39 tonnes of disposals and transfers.

A total of 56% of facilities in the metal ore mining sector that reported disposals of cadmium and its compounds were mines and quarries where gold, silver, nickel and copper were the primary metals extracted.

The map below shows the total quantities of cadmium and its compounds disposed of or transferred for treatment and recycling by facilities in 2020. Disposals of cadmium and its compounds were concentrated mainly in Québec, British Columbia and Ontario (2,143 tonnes, 346 tonnes and 203 tonnes respectively).

Total quantity of cadmium and its compounds disposed of or transferred for treatment and recycling by facilities in 2020.  

Figure 5 below shows that the total quantities of cadmium and its compounds disposed of or transferred for treatment and recycling in the past ten years has remained relatively stable in most sectors. However, in 2019  there was a slight increase in the waste treatment and disposal sector (4,319.7 tonnes) and metal ore mining (4,265.8 tonnes). In 2020, a decrease in the quantities of cadmium and its compounds reported for these two same sectors (1,339 tonne and 1,380.4 tonnes respectively).

Generally speaking, waste management is the sector with the greatest fluctuations, since the quantities disposed of depend on the types of materials entering the facility and being treated, and this varies from year to year.

Government of Canada measures

National acts, regulations, and standards have been put in place to control pollutant releases into the environment, but also to limit exposure to cadmium and its compounds in the Canadian environment.

Cadmium and its compounds are included on the List of Toxic Substances under the Canadian Environmental Protection Act (1999). Under this act, risk management measures have been developed to control releases of cadmium and its compounds produced by thermal electricity generation, metal smelting and steel manufacturing.

Cadmium (inorganic cadmium compounds) has been added to the List of Toxic Substances in Schedule 1 of the Canadian Environmental Protection Act (1999) as it may enter the environment in concentrations or under conditions that may have a harmful effect on the environment or its biological diversity, and may constitute a danger to human life or health. The Government of Canada has the authority to regulate and authorize other instruments to prevent or control the use and/or release of these substances.  Environment and Climate Change Canada and Health Canada are responsible for developing and implementing regulations or other instruments that will prevent or control their use and/or release.

In 2018, Health Canada issued new regulations that protect children from exposure to lead and cadmium. The imposition of a new limit for cadmium, and the lowering of the lead limit, is part of Health Canada’s Risk Management Strategy for Lead.

The Canada Consumer Product Safety Act also includes the Glazed Ceramics and Glassware Regulations. This act regulates consumer products that are completely or partly covered with a glaze or decoration containing lead or cadmium.

Pollution prevention activities

A number of facilities reporting to the NPRI have implemented activities to prevent cadmium releases.

In 2020, facilities that reported releases and disposals of cadmium and its compounds to the NPRI have implemented a pollution prevention plan. These pollution prevention plans targeted these main sectors:

• Pulp and paper
• Metal ore mining
• Oil and gas (conventional and non-conventional extraction)

Below are examples of pollution prevention activities that focus on cadmium and its compounds:

• upgrading of processes to improve efficiency and treatment capacity
• reduced chemical use in manufacturing and processing
• implementation of dust management programs
• modernization of equipment and wastewater treatment systems
• enhancement of maintenance activities, good operating practices and adequate training
• on-site re-use, recycling and recovery
• other pollution prevention activities

Pollution in your neighbourhood

To learn more about the release, disposal and transfer of cadmium and its compounds in your community, please consult the various data products on the NPRI web page.

For a more in-depth analysis, consult the NPRI maps or download the NPRI data to carry out your personalized analysis.