Levels of Exposure to Substances of Concern
The Levels of Exposure to Substances of Concern indicatorFootnote [1] presents the concentrations of cadmium, lead and mercury in blood for all participants in the Canadian Health Measures Survey (CHMS) (aged 6–79 years) and the concentration of polybrominated diphenyl ethers (PBDEs) in blood plasma (aged 20–79 years). These results are intended to establish baseline levels of chemicals to track trends in Canadians over time.
The CHMS was designed as a cross-sectional survey to address important data gaps and limitations in existing health information in Canada. Its principal objective is to collect national-level baseline and reference ranges on important indicators of Canadians’ health status, including those pertaining to exposures to environmental chemicals.
The Report on Human Biomonitoring of Environmental Chemicals in Canada presents the data collected as part of Cycle 1 of the CHMS (2007–2009). The report includes national baseline data on concentrations of environmental chemicals in Canadians.
This information is important in understanding health risk factors, detecting emerging trends in risk factors and exposures, advancing health surveillance and research, and assessing the effectiveness of actions by government and others in Canada.
Biomonitoring can estimate how much of a chemical is present in a person, but cannot tell you what health effects, if any, may result from that exposure. The presence of a chemical in a person’s body does not necessarily mean that it will cause a health effect. Factors such as the dose, the duration and timing of exposure, and the toxicity of the chemical are important to determine whether adverse health effects may occur.
| Concentration / Chemicals | Blood (µg/L) | Blood plasma (µg/L) |
|---|---|---|
| Mercury | 0.69 | --- |
| Lead | 13.4 | --- |
| Cadmium | 0.35 | --- |
| PBDE-47 | --- | 0.06 |
Note: Geometric means were used for the concentration for the total Canadian population, aged 6–79 years for mercury, lead and cadmium, and aged 20–79 years for PBDE-47.
Source: Health Canada (2010) Report on Human Biomonitoring of Environmental Chemicals in Canada: Results of the Canadian Health Measures Survey Cycle 1 (2007-2009). Retrieved on 30 January, 2012.
Exposure
Biomonitoring cannot tell us the source or route of exposure. The amount of chemical measured indicates the total amount that enters the body through all routes of exposure (ingestion, inhalation, skin contact) and from all sources (air, water, soil, food, and consumer products).
Cadmium: Inhalation of cigarette smoke is the major source of cadmium exposure in smokers. Non-smokers are primarily exposed to cadmium through food, although occupational exposure can also be a source. Cadmium can also be present in drinking water; while other minor exposure pathways may include inhalation and releases from consumer products.
Lead: Everyone is exposed to trace amounts of lead through soil, household dust, food, drinking water, and air, due to lead’s natural abundance in the environment and its widespread use for much of the twentieth century. Lead exposure in Canada has decreased substantially since the early 1970s, mainly because leaded gasoline was phased out, uses of lead in consumer paints, in applied paints and other coatings on children’s products have been stringently restricted by regulations and the use of lead solder in food cans was essentially eliminated. Current potential additional sources of lead exposure may include ingestion of chips from lead-based paints on interior and exterior surfaces of older buildings; ingestion of lead-contaminated household dust; ingestion of water from drinking water distribution systems containing lead pipes, lead plumbing fittings, or lead-based solder; ingestion of food grown in areas with high levels of lead in air, water or soil, (e.g., near base metal smelters, combustion sources or roads, or in cities); use of ceramic or glass foodware with lead-containing glazes and mouthing of consumer products containing lead. Housing renovations and hobbies, including stained-glass making, can also increase exposure to lead. Government regulations have helped dramatically reduce the amount of lead found in most of these products.
Mercury: Exposure of the general population is primarily to methylmercury and occurs through the consumption of fish and seafood. To a much lesser extent, the general population is exposed to inorganic mercury from sources such as dental amalgams and broken mercury-containing lamps.
PBDEs: The public may be exposed to PBDEs in food (mostly fishes, dairy products and meat), drinking water, soil and air. Food, including breast milk, represents the principal source of exposure to PBDEs for the majority of age groups; dust is the principal source of exposure for the 0- to 6-month-old, non-breast-fed age group. The age group with potentially the greatest exposure is 0- to 6-month-old breast-fed infants, with breast milk accounting for 92% of the exposure. Health Canada concluded that exposure to PBDEs used in consumer products, via inhalation, dermal contact with dust, or oral contact with household products treated with flame retardants is negligible in comparison with intake from food.
Related indicators
Other information
Return to footnote [1] referrer These indicators complement the Emission of Toxic Substances to Air and Release of Toxic Substances to Water indicators.
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