The level of lead in Canadians' blood has dropped dramatically in 30 years, a new report suggests.

Researchers looked at the levels of lead in the blood of Canadians, the first such national level measurement in three decades. Lead was detected in 100 per cent of the population, Statistics Canada reported Monday.

Lead is a soft, naturally occurring metal used in many products. It can be found in contaminated soil or water, old paint, inexpensive jewelry and other consumer items, such as blinds and leaded crystal.

Average lead concentration for people aged six to 79 measured by the survey between 2007 and 2009 was about one-third of the concentration measured in the 1978-79 Canada Health Survey for the same age group.

In 1978-79, about 27 per cent of Canadians aged six to 79 had blood lead concentrations at or above the intervention level, compared with less than one per cent from 2007-09.

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

Too much exposure to the metal can cause serious illness. In young children, it can impair neurological development. High lead levels can also increase the risk of nervous system and kidney damage.

The decline reflects the removal of major sources of lead from the environment, according to the report.

Sources of lead

"Lead exposure has declined dramatically in the last decades," the report's authors concluded.

"Nevertheless, socio-demographic characteristics, the age of dwellings and certain lifestyle behaviours are associated with higher concentrations. Because of the toxicity of lead at even very low concentrations, there is still a place for ongoing monitoring and public health interventions."

Living in a dwelling that was at least 50 years old, current or former smoking, and drinking alcohol at least once a week were associated with higher concentrations of lead in the blood, after taking age group and sex into account, the agency said.

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.

Lead continues to be used in the refining and manufacturing of products such as lead acid car batteries and electronic equipment, the department said. 

"Lead …can be very toxic at high concentrations, so to see such a marked decrease in humans over time shows that our actions in the 1970s to reduce those contaminants were highly effective," Prof. Linda Campbell, an environmental expert on mercury and metals at Queen's University in Kingston, Ont., said in an email.

Campbell holds the Canada Research Chair in aquatic ecosystem health.

There's no agreement on whether there is a safe level of contamination for lead.

That's why municipalities like Toronto and St. John's continue to warn people about risks of exposure, and crews are working to replace lead pipes running into older homes.

Mercury levels

The Canadian Health Measures Survey also looked at blood levels of mercury, which was found in 88 per cent of Canadians tested.

The average concentration was 0.69 micrograms per litre.

Mercury concentrations were lower for children and teens aged six to 19 than for adults aged 20 to 79, Statistics Canada found.

Health Canada has established a total mercury level in blood guidance of 20 micrograms per litre for the general adult population and eight micrograms per litre for children, pregnant women and women of childbearing age.

Most people are exposed to mercury by eating fish and seafood.

Chronic exposure to high levels of mercury may cause a number of health effects, including:

  • Numbness and tingling in the extremities.
  • Blurred vision.
  • Deafness.
  • Intellectual impairment.

Prenatal exposure to mercury may cause neurological and developmental delays, according to the agency.

The report also measured the level of the bisphenol A or BPA, a chemical used to make some hard plastic containers, bottles and toys — the first time time that BPA levels of Canadians have been measured in a nationally representative sample of the population.

About 91 per cent of Canadians showed detectable levels of bisphenol A, the agency found.

The levels of lead and BPA in Canadians' bodies is a study in contrasts, said Rick Smith, executive director of Environmental Defence in Toronto.

While kids today have a fraction of the lead levels that their grandparents do is a sign regulations are working, he added.

Samples for the study were collected from March 2007 to February 2009 from a representative sample of about 5,600 Canadians aged six to 79 years at 15 sites across the country.