Canned foods sold in Canada contain the estrogen-mimicking chemical bisphenol A at concentrations as much as double the levels that prompted many consumers to shun plastic baby bottles and water bottles made from the controversial material, according to testing conducted for The Globe and Mail and CTV.
The highest amounts were in a food often consumed by children - tomato sauce, which had 18.2 parts per billion. But the news organizations tested 13 other canned goods purchased at Toronto stores, including beer, ravioli, apple juice and cream-style corn, and found bisphenol A in every sample.
Tomato juice had 14.1 ppb, chicken noodle soup as much as 9.9 ppb and ravioli 6.2 ppb.
It is the first time such a review of common, everyday food items has been done in Canada, and indicates there is widespread exposure to the chemical, also known as BPA, among those who eat canned goods, even if they do not use polycarbonate plastic bottles. None of the levels exceed current Health Canada guidelines, industry officials point out.
"These results provide further evidence that Canadians are marinating in this chemical on a daily basis," said Rick Smith, executive director of Environmental Defence, a Toronto advocacy group that has been lobbying Health Canada to ban bisphenol A from food and beverage containers.
Based on the results of animal experiments, researchers have linked low amounts of BPA to effects such as breast cancer and the earlier onset of puberty in girls, among other conditions, with exposures during fetal development and in early life the most damaging.
In April, Health Canada issued a draft risk assessment indicating that it planned to add bisphenol A to the country's list of toxic substances as a precautionary step, based on worries that the margin of safety for infants exposed to the chemical from plastic baby bottles and canned formula wasn't large enough.
Health Canada tested 21 cans of liquid infant formula, and like the Globe/CTV survey, found BPA in every sample, with levels ranging from 2.3 ppb to 10.2 ppb.
The agency is the first in the world to take precautionary action against low-level BPA exposures. It also said it intends to ban polycarbonate baby bottles and announced that it would work with infant formula makers to reduce the amounts leaching from their cans.
But Health Canada wasn't worried about older children and adults inadvertently consuming BPA from canned food, saying the risk was negligible. However, in anticipation that food makers may start reformulating the chemical out of their products, it also said it is "committed to working with the industry to investigate the safety of any possible replacement that industry may consider for bisphenol A-containing epoxy-based linings used in cans."
Many consumers are shunning polycarbonate plastic bottles because they're easy to identify, but it isn't generally known that bisphenol A "is kind of hidden" in cans, Mr. Smith said.
However, the industry insisted that there is no cause for concern. The amounts leaching "are well below any regulatory limit" and have been "deemed to be safe by numerous expert panels," said John Rost, chairman of the Washington-based North American Metal Packaging Alliance, a trade group. He dismissed concerns about bisphenol A leakage as an "unsubstantiated fear."
Cans contain BPA because the chemical is used to make the resin that lines their insides. One way to view cans is that they resemble a thin, plastic-like container on the inside, with a steel or aluminum shell on the outside for structural support.
Trace amounts of bisphenol A are leaching from them for the same reason they have been found to seep from heated baby bottles: The high temperatures used during the canning process to destroy microbes that cause food poisoning also prompt the chemical to migrate out of its resin. The acidic nature of many foods causes some to leak out as well.
Most cans are cooked at microbe-killing temperatures above 100 degrees after their food or beverage contents are added, although lower temperatures around 60 degrees are used on beverages sterilized through pasteurization. Soft drinks create such a harsh environment that microbes can't survive in them; as a result, while pop cans are also lined with a BPA-containing resin, heat sterilization isn't required.
The health risks from the levels found in the Globe/CTV testing are subject to a major dispute among some researchers, who have been finding adverse effects in laboratory animals subjected to trace exposures at or well below current safely limits, and industries using and making the chemical, which have insisted the amounts are harmless.
Other than infant formula, the government did not test cans in its assessment, although it said in response to e-mailed questions from The Globe that it is in the midst of doing so.
Based on Health Canada's current exposure guideline, which was developed in 1995 before it was widely known that BPA could act like a female hormone at very small doses, an adult would need to consume hundreds of cups of the tested products each day to exceed the limit.
But less than half a cup of tomato sauce or a cup of chicken noodle soup would exceed the lowest dose found in recent research to have an adverse effect on animals. That was a 2005 experiment at Tufts University School of Medicine in Boston on mice exposed to amounts far below those detected in the Globe/CTV testing.
Female mice given traces of the chemical during fetal development and early in neonatal life developed double the amount of milk ducts, something the researchers surmised would increase breast cancer risk in humans. The concentration used was only 25 parts per trillion - Health Canada's safe limit is a thousand times above that and the concentrations found in Canadian canned foods were hundreds of times above what was used in the Boston experiment.
One of the scientists on the mouse experiment, Ana M. Soto, professor at Tufts University School of Medicine, said she believes that very small doses of BPA constitute a risk, and consequently avoids canned foods.
"If people stopped eating canned food, nothing bad will happen to them," Dr. Soto said. "On the contrary, it's not like saying don't breast-feed your children. That will be bad."
Dr. Soto also said the safe exposure to BPA is not known among scientists studying the chemical's effects at low exposures.
"It is very difficult to determine what is safe," she said. "The government cannot say that they know that there is a dose that is safe. They cannot say that today because we do not know that as scientists, so they don't know that either."
Hunt's Tomato Sauce
parts per billion
Mini Beef Ravioli
ConAgra Foods says it is "confident in the safety of its products and packaging." It says Health Canada has found that bisphenol A leaching into foods "is not
a concern for most Canadians," while other foreign
regulators have concluded it "does not present
a risk to consumer health."
Chicken Noodle Soup
Loblaw Companies Ltd. endorses a statement on BPA from Food & Consumer Products of Canada, an industry trade group. The organization says amounts in canned foods and beverages "represent a negligible health risk to the general population."
Chicken Noodle Soup
Campbell Co. of Canada says "the overwhelming weight
of scientific evidence
supports the safety of BPA and provides reassurance
that there is no basis for
human health concerns from contact with residual amounts of BPA." It said the testing protocol used will "clearly overstate" BPA levels.
Lassonde Industries Inc. says a child would have to consume 28 litres a day to reach Health Canada's safety limit.
Unico says the amounts detected are less than 1 per cent of the regulatory limit.
The Brewers Association of Canada, responding for the
industry, says it is testing products for their BPA content.
It says checks elsewhere on alcoholic beverages have found levels "far below" safety limits and Health Canada's concerns have been based on exposures to infants up
to 18 months.
Heinz Beans with pork and tomato sauce 2.88 ppb
H.J. Heinz Co. of Canada Ltd. endorses the Food & Consumer Products
of Canada statement on BPA that amounts in canned goods
"represent a negligible health risk to the general population."
Cream Style Corn
General Mills Canada Corp. endorses the Food & Consumer Products
of Canada statement
Peas & Carrots
CanGro Foods Inc.
did not respond to
requests for comment.
The Globe and Mail and CTV News found significant traces of bisphenol A concentration in its combined study of various food.
BISPHENOL A CONCENTRATION, PARTS PER BILLION OF WATER
Hunt's tomato sauce: 18.21
Allen's apple juice: 17.90
Heinz tomato juice: 14.11
Noname chicken noodle soup: 9.93
Labatt beer: 9.27
Campbell's chicken noodle soup: 8.61
Molson beer: 8.19
Del Monte peas and carrots: 6.76
Green Giant cream style corn: 6.52
Chef Boyardee mini been ravioli: 6.17
Heinz zoodles: 4.65
Heinz baked beans: 2.88
President's Choice meal replacement: 2.06
Unico tomatoes: 1.60
SOURCE: XENOANALYTICAL LLC FOR CTV AND THE GLOBE AND MAIL
HOW CANS ARE MADE:
1 - The trimmed can bodies are passed through highly efficient washers that remove all traces of oil in preparation for coating internally and externally.
2 - The clean cans are coated externally with a clear or pigment base for the printing inks (unless paper labels are used). Then the cans pass through a hot-air oven to dry the lacquer.
3 - The inside of each can is sprayed with a lacquer. This special layer is to protect the can itself from corrosion and its contents from any possible interaction with the metal.
4 - The finished can bodies are transferred to a warehouse to await filling.
HOW CANS ARE FILLED:
5 - Cans are turned upside down and cleaned using high-pressure air and water, then righted.
6 - They then are filled with carbon dioxide, which replaces all air in the can.
7 - Up to 2,000 cans per minute are filled with a food or beverage and sealed. Throughout this process, it is estimated that the can will travel about 1.5 kilometres around the factory.
8 - Beer and some juice will be pasteurized in the can using variable temperature water jets.