Lead concentrations in the Canadian population, 2007 to 2009
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Lead is a heavy metal that occurs naturally in the environment. People can be exposed to lead from air, water, food, dust, consumer products and certain occupations and hobbies. Blood lead levels, which are commonly used to evaluate human exposure, reflect recent exposure and may also represent past exposure as a result of movement of lead from bone into blood.
High lead levels can increase the risk of nervous system and kidney damage. In Canada, the current blood lead intervention level is 10 micrograms per decilitre (µg/dL). For concentrations at or above this level, actions are recommended to reduce lead exposure. Some studies have found that children may experience health effects with blood lead concentrations below 10 µg/dL.
Since the 1970s, lead is no longer added to automotive gasoline or used as solder in food cans, and lead limits in paint have been reduced. However, it can still be found in some consumer products such as lead acid car batteries, plastic mini–blinds, toys and jewellery. Lead that has been released into the environment does not break down over time; as a result, lead from previous uses can continue to be a source of exposure
The Canadian Health Measures Survey (CHMS) measured lead and other environmental contaminants in the Canadian population. From 2007 to 2009, blood lead was detected in 100% of the population aged 6 to 79 years. The geometric mean concentration was 1.34 µg/dL. This level is about three times lower than the level measured in the 1978-79 Canada Health Survey. Furthermore, less than 1% of Canadians had blood lead concentrations at or above the intervention level of 10 µg/dL from 2007 to 2009. Thirty years earlier, this figure was 27%.
Blood lead concentrations in the Canadian population, by age group and sex, 2007 to 2009 (geometric means)
Note: A geometric mean is a type of average that is less influenced by extreme values than the traditional arithmetic mean. The geometric mean provides a better estimate of central tendency for highly skewed data. This type of data is common in the measurement of environmental chemicals in blood and urine.
Source: Canadian Health Measures Survey, 2007 to 2009
Blood lead concentrations were higher in adults than in children. The geometric mean concentration increased with age through the adult years, reaching 2.08 µg/dL among adults aged 60 to 79. In general, males had higher blood lead concentrations than females.
Certain socio-demographic characteristics were found to be statistically significant in relation to blood lead concentrations. People with the lowest household incomes had higher blood lead concentrations than those with highest household incomes. As well, people who were born outside of Canada had higher blood lead concentrations than those born in Canada.
People who lived in homes built more than 50 years ago had higher blood lead concentrations than those who lived in homes less than 20 years old. Blood lead concentrations were also higher in people who were current or former smokers, and in people who drank alcohol once or more per week.
More information on this topic is available in "Lead and bisphenol A concentrations in the Canadian population" Health Reports (82-003-X).