Yolande Sprague could be forgiven for feeling virtuous.
Four years ago, just after giving birth to her second child, the stay-at-home mom heard about BPA, a chemical inside some plastics that can leach into water or food slowly over time, potentially causing serious health problems like cancer. Unwilling to take any risks, she ran to Babies "R" Us, which had a program to exchange baby bottles containing BPA, and walked out with $100 in rebates.
If only life were so easy.
What Sprague didn't realize is that BPA, or bisphenol A, is ubiquitous. Simply put, just about anything you eat that comes out of a can — from Campbell's Chicken Soup and SpaghettiOs to Diet Coke and BumbleBee Tuna — contains the same exact chemical.
The exposure to BPA from canned food "is far more extensive" than from plastic bottles, said Shanna Swan, a professor and researcher at the University of Rochester in New York. "It's particularly concerning when it's lining infant formula cans."
BPA is the key compound in epoxy resin linings that keep food fresher longer and prevents it from interacting with metal and altering the taste. It has been linked in some studies of rats and mice to not only cancer but also obesity, diabetes and heart disease.
Trade groups for chemical and can manufacturers say they stand behind the chemical, and point to some studies from governmental health agencies that deem BPA safe and effective for food contact. They also note that its use has substantially reduced deaths from food poisoning.
But in January, the U.S. Food and Drug Administration for the first time expressed "some concern" about BPA. Propelled in part by recent independent scientific studies and also bowing to mounting concern from the public and consumer groups, the agency announced that it would tap $30 million in federal stimulus funds to study the chemical's potential effects on the human body.
Though it is not clear how economically stimulating the study will be, its results are anxiously awaited in industry and consumer circles. The report, due late in 2011, is being done in collaboration with the National Institutes of Health.
"BPA has not been found or been proven to harm either children or adults, but because children ... in the very early stages of development are exposed to BPA, the data that we're getting deserves a much closer look," Deputy Health and Human Services Secretary Bill Corr said earlier this year.
What is clear, however, is that unlike the case with plastic, there are no economically viable alternatives to the chemical in epoxy resins right now.
"If it's in baby bottles, then I can imagine it's in a lot of other things," said Sprague, who has a history of premature deliveries, but is due to give birth to a boy in September. "Everybody gets breast cancer now. It's scary. Is it because of BPA? I don't know."
BPA VERSUS DNA
One scientist helping to lead the charge against BPA is Yale University physician, professor and researcher Hugh Taylor. His research has shown that the chemical alters the way genes react to estrogen, and could open the door for infants in utero to develop cancer much later in life.
"I tell my pregnant patients to avoid products containing it," he said. "Even a fleeting exposure in pregnancy can cause lasting damage."
The studies by Taylor are certainly eye-opening. They have shown that the chemical alters the way DNA operates, a process known as an epigenetic change.
On each strand of DNA a group of carbon molecules binds to receptors that help turn genes on or off. In the presence of BPA, though, many of those carbon molecules can be removed from DNA, and with them the switch.
Think of the carbon groups as a kind of lock, and the DNA receptors as a gate. When the lock is removed, the gate can swing open, greatly increasing the risk for estrogen to flow through later in life, interact with DNA and cause cancer.
"It has permanent, lasting effects," said Taylor, donning a white coat in his New Haven, Connecticut, lab surrounded by beakers, microscopes, pipettes and other tools of the scientist's trade. "The adult exposure is concerning, but I think the fetal exposure is worse."
To study the way BPA may affect children in utero, Taylor injected pregnant mice with high doses of the chemical five days into their 21-day gestation cycle. He found that the mice exposed to BPA in the womb lacked the "gate" on their DNA receptors and were more susceptible to estrogen for the rest of their lives.
Since many foods contain natural estrogen — soy, for instance — Taylor believes his studies suggest complications could arise down the road simply from eating basic foods, never mind estrogen supplements that many women take as they enter menopause. "In the mouse models, they're more prone to cancer," Taylor said.
As a gynecologist, Taylor studied the effects primarily on female mice. The long-term impact of increased BPA on DNA receptors in males, he said, remains unknown. His research is also limited because he can't test BPA on unaffected humans. "We all have it in our bodies, so there's no way to test a population without it," he said. "You'll never have the perfect experiment in humans to prove this."
Right now Taylor is studying just how BPA removes the carbon groups from DNA — in effect the specific process that removes the "lock" — and hopes this will shed further light on how the chemical interacts with the body.
He acknowledges BPA's role in food safety but says people should be made aware of the potential danger. "We always balance the risk with the benefits in our lives," he said. "There's a price we pay for modern society and convenience."
Frederick vom Saal, a professor at the University of Missouri who is studying BPA independently from Taylor, is far less diplomatic. Known as an aggressive crusader against the chemical, he said that if BPA were treated as a drug, "it would have been pulled immediately" by regulators.
A EUREKA MOMENT
Inside canned food, the thin layer of epoxy resin sits between the food and metal can, helping to keep the two from interacting and preventing rust.
The resin is sprayed into the can and dries almost instantly. Thousands of companies, such as Campbell Soup Co and Coca-Cola, use it to line their cans. Without it, food would perish far faster. Cans lacking the chemical would explode on store shelves when contents reacted with the metal.
First synthesized in 1891, BPA is a commercial hardener, making it great to use in a wide variety of applications, ranging from plastic canoes to headlights to cash register receipts. As a key building block for epoxy resin, it acts as part of the compound's polymer base, and was first used in the 1940s in canned foods.
A breakthrough product in its day, it has also been enduring. "There's just something about it," said Steve Russell, the head of the plastics division for the American Chemistry Council, an industry trade group. "When they figured it out, it was one of those 'eureka' moments."
Because BPA has been presumed to be safe without question for so long, very little research has been undertaken to find commercially viable substitutes in canned goods. "At the moment, there is no single epoxy resin which provides the same degree of food safety, shelf stability and cost-effectiveness for maintaining the shelf life of fruits and vegetables," said Russell.
That was not the case with plastic bottles. In that industry, replacements have been much easier to come by. Alternatives to plastic with BPA include polyethylene, most commonly used to make shopping bags, and polypropylene, which makes water bottles squeezable.
To be sure, non-BPA-based resins exist, but they are much more expensive. That's a challenge for an industry that is sensitive about price differences to the fraction of a penny.
Michigan-based Eden Foods, for example, markets beans and rice in BPA-free cans made by Ball Corp, but they cost 14 percent more than traditional ones. With the can itself representing one of the largest costs for food makers, switching to an alternative likely would boost prices and hurt consumers — especially the legions of coupon-clippers struggling to make ends meet.
Ball uses an enamel mix comprised of natural resins from pine and balsam fir trees, a mix that was used before BPA became popular more than 50 years ago. "When you're talking about half the cost of a can of food being just the can itself, in an extremely hyper-competitive environment, it's a big deal," said Michael Potter, president of Eden Foods.
Nevertheless, the company has been able to survive due to growing interest from natural food devotees, he said. Eden still markets tomato products in cans containing BPA, noting that the FDA hasn't signed off on any other types of can linings for acidic foods. But Potter says he is working with Ball on a replacement that he hopes will hit shelves in the next few years.
Other alternatives are being developed. Earlier this year Michael Jaffe, a research professor at the New Jersey Institute of Technology, received a patent for a corn sugar-based resin that mimics BPA's structure but doesn't have the harmful side effects.
Still, the resin is years away from commercial use, and the price of switching to it remain unknown. "The final cost will clearly be linked to volume," Jaffe said. "But I see no reason why these resins can't be competitive with BPA."
Back at the University of Rochester, Swan and her colleagues are studying just how much BPA is absorbed by the body depending on how much canned food is eaten. Their report is due out later this year.
OF MICE AND METABOLIZATION
For the time being, the chemical industry is not just sticking with BPA. It is also warning consumers to be wary of anything that claims to be an acceptable substitute but may not have undergone rigorous testing.
"We're all parents, and we can all understand that everybody wants to do the best for their kids," the ACC's Russell said. "But in doing so we need to understand that we're doing it not because the government agencies around the world say they're not safe, you're doing so because in some places, some people want to be extra safe. It comes down to the degree of uncertainty that you're comfortable with."
Part of the concern many in the chemical industry have with studies like Taylor's is that they tend to use very large doses of BPA. Taylor injected his mice with five milligrams of the chemical — far more than anyone would be exposed to eating from just one can.
The chemical industry maintains that BPA metabolizes very quickly in the body and is excreted before it can even interact with cells. "The levels of chemical that you would be exposed to from using products containing BPA, including epoxy lining in food containers, is so small that all these government agencies have looked at it and have said, 'Yeah, even if all these horrible things that BPA is said to cause were true, the exposure levels are so small that we're not convinced there's an actual risk here," Russell said. "That's why they continue to allow them to be used."
For Yale's Taylor, any amount of a harmful chemical is too much for some. "We can argue over what is a safe dose, but if I'm pregnant I'm going to avoid it," he said. "The adult exposure is concerning, but I think the fetal exposure is worse."
Given this chasm, all eyes are on the FDA. The agency has long insisted that the chemical is safe, so it did not go unnoticed when it said it would use funds from the American Recovery and Reinvestment Act of 2009 to study what BPA does to the human body. "We need to know more," Deputy FDA Commissioner Dr. Josh Sharfstein told reporters earlier this year.
Adding to the confusion, his counterpart across the northern border disagrees. Health Canada, that country's top health regulator, bans BPA in plastic baby bottles, but earlier this month the agency said that the levels of BPA levels in canned food "are not considered to represent a human health concern."
Leading companies and industry organizations reference both the FDA and Health Canada's current stance on BPA in plastic resin, saying they stand behind findings from those and other agencies that the chemical is safe. "We welcome the FDA's current research into BPA," said Scott Openshaw of the Grocery Manufacturers Association. "We rely on the proper regulatory authorities to determine if something like this is unsafe."
The North American Metal Packaging Alliance, a trade group for canned food and beverage makers, says BPA provides "real, important and measurable health benefits." "A lot of younger people today don't even understand what a bulging can is, but most of our grandparents understand that a bulging can is a contaminated can," said John Rost, who has a Ph.D. in chemistry and is chairman of the alliance. "Through the use of epoxy coatings in metal packaging, there has not been a food-borne illness case in more than 33 years."
Nevertheless, the backlash against BPA has reached corporate America. In April, Coca-Cola shareholders rejected a proposal to force the company to issue a report on potential alternatives to BPA and how the chemical could affect market share. Executives insisted that the report would not offer any "additional or useful information."
A person weighing 135 pounds (61 kg) would need to ingest more than 14,800 12-ounce cans of a beverage in one day to approach the FDA's acceptable daily limit for BPA consumption, Coca-Cola said.
For BPA manufacturers, including Dow Chemical and Hexion Specialty Chemicals, the chemical is not a large revenue base. If it were banned in food applications tomorrow, both companies and their peers would likely move forward without so much as a hiccup.
According to SRI Consulting, about 4.1 million tons of plastic resin were used globally in 2006, the most recent year for which data is available. The industry has the capacity to produce about 4.6 million tons, though, and Western Europe actually uses more than the United States.
Back at Yolande Sprague's house in Dover, New Hampshire, her five-year-old son, Eddie, is looking through the cupboards for a snack.
His parents don't want to freak out about BPA; they know that statistically it's saved lives by reducing deaths from food poisoning. Indeed, Eddie's chance of hitting his 6th birthday is dramatically higher because he was born in 2004 rather than 1804, when children routinely died of food-related illnesses.
Even so, many parents remain concerned. Just what is an acceptable amount of BPA to ingest? Should we be knowingly ingesting a potential carcinogen into our bodies, even at minuscule levels? Why aren't there better, cheaper alternatives?
For now, families like Sprague's weigh their options every day on canned food, though experts like Yale's Taylor point out that if the end result is more people eat fresh fruits and vegetables, that wouldn't be a bad thing.
"I don't use canned foods on a daily basis," said Sprague, 26. "But if I did, then I would cut back."
The wind blows softly through Sprague's screened sliding door, and papers flutter off her fridge. Her son, Eddie, runs to the cupboard, grabs a can and turns to his mother.
"Mom," he asks. "What kind of soup is this?"