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Summary of key findings

Lead and bisphenol A concentrations in the Canadian population

New data from the 2007-2009 Canadian Health Measures Survey (CHMS) show that 100% of Canadians aged 6 to 79 had detectable concentrations of lead in their blood, and 91% had detectable concentrations of bisphenol A (BPA) in their urine.

These findings are included in the third data release from the CHMS, which collected biomonitoring data from a nationally representative sample of Canadians.  As part of the physical examination component of the survey, blood and urine samples were collected and analyzed for chronic and infectious diseases, nutritional biomarkers, general health and a wide range of environmental chemicals and their metabolites.  Blood lead and urinary BPA were among the environmental chemicals that were measured.

Blood lead concentrations have fallen dramatically over the past 30 years.  The last time blood lead was measured at a national level was in 1978-1979, when the Canada Health Survey estimated a geometric mean concentration of blood lead of 4.79 μg/dL among Canadians aged 6 to 79 years.  By 2007-2009, the geometric mean blood lead concentration had fallen to 1.34 μg/dL in the same age group.  This decline reflects the removal of major sources of lead from the environment.  Since the 1970s, lead has no longer been added to automotive gasoline or used as solder in food cans, and lead limits in paint have been reduced.

Blood lead levels, which are commonly used to evaluate human exposure, reflect recent exposure and may also represent past exposure as a result of lead mobilization from bone into blood.  People can be exposed to lead from air, water, dust, consumer products and certain occupations and hobbies.

High blood lead levels can increase the risk of brain and kidney damage.  A blood lead concentration at or above 10 μg/dL is considered an intervention level, though recent studies have found health effects among children at lower concentrations.

In 2007-2009, fewer than 1% of Canadians aged 6 to 79 years had a blood lead concentration above 10 μg/dL, compared with 27% of Canadians in 1978-1979. 

Blood lead concentrations were higher among adults in 2007-2009 than in children.  Blood lead concentrations increased through the adult years, with the highest concentrations found among adults aged 60 to 79 years.  Males had significantly higher blood lead concentrations than did females in all age groups, except 6- to 11-year-olds.

Controlling for age group and sex, higher blood lead concentrations were associated with  lower household income, being born outside of Canada, living in a dwelling at least 50 years old, current or former smoking, and drinking alcohol at least once a week.

The CHMS is the first national survey to measure Canadians’ exposure to BPA.  BPA is an industrial chemical used primarily in polycarbonate plastic (such as food containers and water bottles), and epoxy resins (such as the protective linings for canned food and beverages). It is a recognized endocrine disruptor, and reproductive toxicity has been identified as a key health effect of exposure to high concentrations.  No guidance values are currently available in Canada for urinary BPA.

In 2007-2009, Canadians aged 6 to 79 years had a volume-based geometric mean BPA concentration of 1.16 μg/L.  This is consistent with the results of other studies of reference populations reporting mean or median concentrations of 1 to 3 μg/L.

Overall, males had higher volume-based BPA concentrations than did females, a difference largely attributable to higher concentrations among men aged 40 to 79.

Standardizing BPA with urinary creatinine concentrations – a method to account for urine concentration/dilution – resulted in a geometric mean BPA concentration of 1.40 μg/g creatinine for the population aged 6 to 79 years.  Children 6 to 11 years old had a significantly higher creatinine-standardized geometric mean BPA concentration than did any other age group.

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For more information about this article, contact Tracey Bushnik (1-613-951-2301: Tracey. Bushnik@statcan.gc.ca) Health Analysis Division, Statistics Canada.