The risks posed by a substance are determined by both its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent of exposure to people and the environment.
When needed, the Government implements risk management measures under CEPA 1999 and other federal acts to help prevent or reduce potential harm.
Silver is associated with ecological effects; however, at levels of exposure considered in the screening assessment, the Government concluded that the 7 substances in the Silver and its Compounds Group are not harmful to the environment. In addition, the Government concluded that silver and its compounds, including but not limited to the 7 substances in the group, are not harmful to human health at levels of exposure considered in the assessment.
The screening assessment of silver and its compounds focused on the silver moiety and therefore considered silver in its elemental form, silver-containing substances, and all forms of silver found in the environment. As such, all silver-containing substances beyond the 7 substances in the Silver and its Compounds Group were considered.
According to information gathered by the Government, silver has a wide variety of uses, including the manufacturing of silver bars, coins, jewelry, medals, silverware, silver-containing substances and preparations, glass products, and soap and cleaning compounds. It is also used in brazing and soldering, catalysis, cloud seeding (the process of weather modification using different chemical agents), and electronics.
In Canada, silver may also be used in a range of products available to consumers, including drugs, natural health products, cosmetics, as a formulant in pesticides, and toys. It is also a permitted food additive and may be used as a component in the manufacture of food packaging materials.
Human and ecological exposures
The screening assessment indicated that as silver is a naturally occurring substance, Canadians are exposed to silver and its compounds from environmental sources (for example, air, dust, and drinking water) and food, as well as products available to consumers.
The human health exposure and risks of silver and its compounds were characterized and published in the biomonitoring-based approach 2 science approach document. In that approach, human biomonitoring data (measured levels in human whole blood used for estimating exposure) were compared against biomonitoring guidance values (associated with health effects) that are protective of human health.
Silver is naturally released to the environment from the weathering of soils and rocks.
Silver may also be released to the environment from industrial activities. This includes during its production (for example, mining, processing, smelting, and refining), during the manufacture of silver-containing substances, from product disposal (landfill leachates following waste disposal) and through other activities (cloud seeding). Releases of silver and its compounds are reported through the National Pollutant Release Inventory (NPRI).
Key health and ecological effects (hazard)
The critical effect identified for characterizing the risk to human health for silver was argyria (characterized by blue or blue-greyish staining of the skin and mucous membranes). Argyria is not associated with damage to any specific target organ.
Organisms exposed to silver rapidly take up the substance and accumulate it in internal organs and other tissues. Silver has been demonstrated to cause mortality as well as growth and reproductive effects in aquatic organisms at very low concentrations, and to benthic and soil-dwelling organisms at moderate concentrations.
Consideration of vulnerable populations
There are groups of individuals within the Canadian population who, due to greater susceptibility or greater exposure, may be more likely to experience adverse health effects from exposure to substances.
Certain subpopulations are routinely considered throughout the screening assessment process, such as infants, children, and people of reproductive age. For instance, age-specific exposures are routinely estimated and developmental and reproductive toxicity studies are evaluated for potential adverse health effects.
For silver and its compounds, Canadian human biomonitoring data were used to inform the consideration of these subpopulations and take them into account in the risk assessment outcomes.
Risk assessment outcomes
It was determined that the risk to human health from silver and its compounds is low at levels of exposure considered in the screening assessment. This was based upon a comparison of total levels of silver measured in human whole blood and levels associated with health effects.
Considering all information presented, it was also determined that there is low risk of harm to the environment from the 7 substances in the Silver and its Compounds Group.
Screening assessment conclusions
The Government concluded that silver and its compounds are not harmful to human health at levels of exposure considered in the assessment.
The Government also concluded that the 7 substances in the Silver and its Compounds Group are not entering the environment at levels that are harmful.
Preventive actions and risk reduction
Although a risk to human health or the environment has not been identified at levels of exposure considered in the screening assessment, there may be a concern if exposure to silver and its compounds were to increase. As a result, silver and its compounds may be considered in future initiatives to obtain additional information.
Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.
Silver and its compounds may be found in products available to consumers. Canadians should follow any safety warnings and directions related to the product and dispose of products responsibly according to municipal or local guidelines.
Engineered nanomaterials containing silver that may be present in the environment or in products are not explicitly considered in the exposure scenarios of the screening assessment, but measured concentrations of silver in the environment or human biomonitoring could include silver from these sources. Similarly, the screening assessment did not explicitly consider ecological or health effects associated with nanomaterials containing silver. Nanoscale forms of substances currently on the Domestic Substances List will be addressed in a separate initiative.