A Health Canada study suggests most Canadians have the chemical bisphenol A in their urine and all have traces of lead in their blood.

The 2009-2011 report on environmental chemicals shows the plastics ingredient bisphenol A, or BPA, was detected in the urine of 95 per cent of Canadians aged three to 79.

Children aged three to five and six to 11 had the highest average concentration of BPA, while adults 60 to 79 had the lowest average level.

Current BPA levels do not differ from those found in similar testing in 2007 to 2009, and the health effects of such exposure are unknown.

While lead can be harmful at any age, but especially to children, the study shows almost all Canadians had levels below that where treatment is recommended.

And blood-lead levels have been dropping — the current average lead level for six- to 79-year-olds is about 11 per cent lower than the 2007-2009 average and four times lower than that measured in 1978-1979.

"This latest collection of national biomonitoring data will build on the [previous] information collected … for future monitoring and research," said Dr. Robert Cushman, Health Canada's special medical adviser. "It will improve our understanding of human chemical exposure and help with the development of policies to protect the health of Canadians."

Bisphenol A, a chemical used to make some plastics and epoxy resins, is found in food and beverage containers and in the protective linings of food and beverage cans.

BPA levels likely indicate recent exposure

BPA is rapidly broken down in the body and excreted in urine, so levels in urine are thought to indicate recent exposure.

Animal studies have suggested the chemical may affect brain development, leading Canada and some other countries to ban its use in baby bottles. But Health Canada has said that exposure to BPA through food packaging is not expected to pose a health risk.

Erica Phipps of the Canadian Partnership for Children's Health and Environment welcomed this latest biomonitoring research on the population's exposure to potentially toxic environmental substances.

"The dataset on three- to five-year-olds gives us a clearer picture of chemical exposures for the most vulnerable among us — our children — and provides an important benchmark against which to measure progress."

The 2009-2011 Canadian Health Measures Survey collected data from a representative sample of 6,400 Canadians. The survey is the first to include measurements for children aged three to five.