Lead levels drop in Canadians, but study finds levels of BPA, mercury

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OTTAWA – A new federal study has found that blood lead concentrations among Canadians have fallen dramatically since they were last measured 30 years ago.

But the Canadian Health Measures Survey, released Monday by Statistics Canada, said 91 per cent of Canadians aged six to 79 had bisphenol A in their urine.

The study, conducted between 2007 and 2009, also found 88 per cent had detectable concentrations of mercury in their blood.

The study analyzed blood and urine samples for indicators of more than 80 environmental contaminants and chemical substances.

It found lead in 100 per cent of those tested, but less than one per cent had concentrations at or above the intervention level of 10 micrograms per decilitre of blood.

Older adults and males had significantly higher lead concentrations.

“Lower household income, being born outside Canada, living in a dwelling at least 50 years old, current or former smoking, and drinking alcohol at least once a week were associated with higher (lead levels),” said the study.

“Although … concentrations have declined dramatically since the 1970s, socio-demographic characteristics, the age of dwellings, and certain lifestyle behaviours are associated with higher levels.”

Meanwhile, the plastic hardener bisphenol A was detected in the urine of 91 per cent of those surveyed.

It’s the first time bisphenol A concentrations were measured nationally, and the survey says those measured had a mean concentration of 1.16 micrograms per litre in their urine.

That’s consistent with results from international studies, which have been reporting mean or median concentrations of one to three micrograms per litre.

The chemical has been used in water bottles, canned food lining and hundreds of other household items.

Some scientists believe exposure to bisphenol A can harm the reproductive and nervous systems and possibly promote cancers. They point to dozens of animal studies, though the negative effects have not been recorded in human studies.

The Canadian study found concentrations of BPA in urine were higher for children aged 6 to 11 than they were for adults aged 40 to 79. The study found the highest concentrations in teens.

“Given the short half-life of orally ingested BPA and the high frequency of detection, the … data suggest continual widespread exposure in the Canadian population,” it said.

It also found total blood mercury in 88 per cent of those tested.

The geometric mean 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.

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