The finding helps to allay concerns that BPA, which mimics the hormone estrogen, persists for long periods in the environment — but critics say the study should not stall efforts to eliminate the chemical altogether.
"A large portion of the BPA that is estimated consumed in Canada is actually reacted/destroyed during its service life," says the $44,000 research report by Cheminfo Services Inc.
The study suggests between 44 per cent and 68 per cent of the BPA consumed in Canada in 2010 was destroyed in the use of products, such as the epoxy coatings often used to line the inside of food cans.
Another 24 per cent to 43 per cent went into landfills, while less than 14 per cent was released, recycled, incinerated or found its way into sludge.
The preliminary review of 12 Canadian sectors that use BPA, dated March 26 this year, was obtained by The Canadian Press under the Access to Information Act.
The Harper government has been a global leader in efforts to limit exposure to BPA, banning the chemical from polycarbonate baby bottles in 2008 after studies demonstrated some leaching into the fluid. The U.S. Food and Drug Administration issued its own baby-bottle BPA ban only last month.
And in late 2010, the substance was added to an official list of toxic substances in Canada. Environment Canada since April this year has also required key industries to develop mitigation plans to reduce the amount of BPA they release into the environment.
The Cheminfo study cautions that more study is needed to verify the initial research, which focused on a range of products in the Canadian marketplace, including brake fluids, tires and cleaning products.
The findings won praise from Environmental Defence, a Toronto-based non-profit group, which has been pressing government and industry to eventually eliminate use of all BPA.
"We're happy that BPA is on the decline," spokeswoman Maggie MacDonald said in an interview.
"This is something we view as a success story because government has shown leadership on the issue, but also because businesses have shown leadership."
"We'd like to see more progress," she added, "and have BPA taken out of products completely and see the day when BPA isn't entering the environment."
BPA mimics the hormone estrogen, and has been linked to higher risks for breast cancer, heart disease and even obesity, though there is no broad scientific consensus about its precise toxicity or what levels are unsafe.
Some Canadian retailers, such as Mountain Equipment Co-op and Lululemon, have voluntarily removed BPA-containing water bottles from their shelves. Some firms have also adopted BPA-free manufacturing processes to respond to consumer concerns.
A spokeswoman for Environment Canada said the department has a program to monitor whether the large amount of BPA that enters landfills is escaping.
"Environment Canada has a landfill leachate sampling program in place to monitor potential releases of toxic substances to the environment, including BPA," Celine Tremblay said in an email.
"The department will continue to assess results from this program to determine if additional action is required."
She added that the department "will continue to monitor BPA on a national scale in wastewater, landfills and surface water and to keep abreast of any new information obtained from other jurisdictions."
"The information gathered will be used to assess whether any additional actions are taken."
The report by Cheminfo, a Markham, Ont.-based technical consultant, highlights the use of BPA in so-called thermal papers, that is, coated sheets and rolls that are heat sensitive and used to print sales receipts, labels, airline boarding passes and lottery tickets.
Most of Canada's used thermal paper — with its resident BPA — winds up in landfills, although an estimated 30 per cent is recycled, according to the study.
Thermal paper, when handled, readily sheds its coating's BPA, which can be absorbed through the skin, though some thermal papers do not use the chemical.
One 2011 analysis by the U.S. firm Prosolia Inc. found very high levels of residue BPA on Canadian $5 bank notes, apparently the result of the currency's direct contact with thermal receipts, suggesting another avenue for the spread of the chemical.
Environmental Defence is pressing for an end to the manufacture of all BPA-laced thermal paper. Tremblay says Environment Canada expects to develop an agreement with paper recyclers next month to reduce amounts of BPA that re-enter paper products, such as toilet paper or paper towels.
Some health experts say consumers should avoid handling thermal-paper receipts, and seek out glass food containers or buy only those cans labelled BPA-free.