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Study: Lead, mercury and cadmium levels in Canadians
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Less than 1% of Canadians aged 6 to 79 had blood lead concentrations in 2007/2008 above current Health Canada thresholds established for the general population, and less than 1% of Canadians aged 20 to 79 had total blood mercury concentrations above current Health Canada thresholds for adults. Blood lead concentrations have fallen substantially since 1978 when national levels were last measured.
There is no Canadian threshold level established for blood cadmium. However, blood cadmium levels in Canadians were similar to those in the general populations of the United States and Germany. They are among the few countries that have conducted nationally representative biomonitoring surveys that include testing for heavy metals.
While most Canadians had measurable amounts of these three heavy metals in their blood, these amounts do not necessarily result in adverse health effects.
Blood lead concentration
The mean blood lead concentration in the Canadian population aged 6 to 79 was 1.37 micrograms per decilitre in 2007/2008. More than 99% of Canadians aged 6 to 79 had measurable amounts of lead in 2007/2008.
The current Health Canada blood lead "guidance level," or threshold, for the general population is 10 micrograms per decilitre. This threshold is the level above which follow-up actions may be considered to reduce exposure.
In 1978/1979, results of the Canada Health Survey showed that 25% of Canadians aged 6 or older had blood lead concentrations above this threshold. The current figure of less than 1% represents a substantial decline.
Much of this decline may reflect the phase-out of leaded gasoline, lead-containing paints, and lead solder in food cans since the 1970s.
Sources of lead exposure include lead-based paint, lead plumbing, food grown in lead-contaminated soil, and products that contain lead or lead-based paints.
Note to readersThis release, based on an article in Health Reports, presents the first data from the Canadian Health Measures Survey, the most comprehensive direct health measures survey ever undertaken on a national scale in Canada. The survey is being conducted by Statistics Canada in partnership with Health Canada and the Public Health Agency of Canada. It includes measurement of the heavy metals (lead, mercury and cadmium) which are toxic to humans at excessive levels. National blood lead levels have not been measured since 1978. This release presents preliminary data on blood levels of lead, total mercury and cadmium in just over 2,600 Canadians aged 6 to 79 from the first 8 collection sites. The survey will be collecting data from about 5,000 Canadians aged 6 to 79 at 15 sites across Canada up to March 2009. Survey data will be used to assess the population for a broad range of environmental chemicals, chronic diseases, nutritional status and infectious diseases. The data will also provide a baseline for emerging trends and enable comparisons with other countries. |
Total blood mercury concentration
The mean total blood mercury level of Canadians aged 6 to 79 in 2007/2008 was 0.76 micrograms per litre. About 90% of these individuals had measurable amounts of total mercury in their blood.
However, less than 1% of Canadians aged 20 to 79 had total mercury concentrations above the current Health Canada blood threshold of 20 micrograms per litre. (The guidance value for mercury applies only to adults.) Unlike lead, this is the first time that national blood mercury levels have been measured in Canadians.
Canadians overall had similar, or slightly higher levels, than those of two other study groups: the general population in Germany and females aged 16 to 49 in the United States.
The primary source of exposure to mercury is through the consumption of fish and seafood.
Blood cadmium concentration
The mean blood cadmium level of Canadians aged 6 to 79 was 0.35 micrograms per litre in 2007/2008. The vast majority (98%) had measurable amounts of cadmium in their blood.
No Canadian blood cadmium guidance value has been established for the general population. Occupational exposure guidance values exist, but they are not applicable to the population overall.
Blood cadmium levels of Canadians were similar to those of the general population of the United States and Germany.
For the non-occupationally exposed population, cigarette smoking is considered to be a major source of exposure.
Definitions, data sources and methods: survey number 5071.
The article, "Lead, mercury and cadmium levels in Canadians," which is part of Health Reports, Vol. 19, no. 4 (82-003-XWE, free), is now available from the Publications module of our website.
For more information about this article, or to enquire about the concepts, methods or data quality of this release, contact Suzy Wong (613-951-4774; suzy.wong@statcan.gc.ca), Statistics Canada, or Health Canada Media Relations (613-957-2983).
Additional information about biomonitoring, and specifically, lead, mercury and cadmium can be found at (hc-sc.gc.ca) and (chemicalsubstanceschimiques.gc.ca).
To learn more about the Canadian Health Measures Survey, contact Jeanine Bustros (613-951-9476; jeanine.bustros@statcan.gc.ca), Physical Health Measures Division.
For more information about Health Reports, contact Christine Wright (613-951-1765; christine.wright@statcan.gc.ca), Health Information and Research Division.
