Concern over the health effects of bisphenol A (BPA) in this country have mounted steadily in recent years, to the point where in October 2008, the Canadian government became the first in the world to ban the import and sale of polycarbonate baby bottles containing the chemical.
Research has linked bisphenol A — a compound found in plastic food and drink containers, compact discs, electronics and automobile parts, and in the lining in some metal cans — to a number of adverse health effects such as infertility, cardiovascular problems, diabetes and feminization of developing male infants.
Testing by Health Canada found "BPA-free" baby bottles manufactured by the following brands leach trace quantities of bisphenol A:
- Dr. Brown's.
- Born Free.
- Green to Grow.
The government's 2008 edict was aimed at assuaging the fears of many concerned parents, who can now ostensibly rest assured that baby bottles labeled "BPA-free" do not contain any amount of the contentious chemical.
But a June 2009 study carried out by Health Canada appears to cast at least some doubt on this. The results of the study, published in the journal Food Additives and Contaminants, show that a number of non-polycarbonate baby bottles labeled "BPA-free" leached trace amounts of the chemical into their contents.
On August 7, 2009, Health Canada made public the brands that were tested. The non-polycarbonate bottles that were found to have detectable levels of BPA are listed in the accompanying sidebar.
Health Canada says the trace amounts should be of no concern to parents.
"Bottles made from non-polycarbonate plastic may contain very low level, trace amounts of BPA resulting from cross-contamination caused by the ubiquitous nature of BPA. Detection of BPA in the non-polycarbonate plastic bottles may also be due to improved sensitivity of instruments in laboratories. There is often no such thing as absolute zero due to cross-contamination and prevalence of many substances in the natural environment," Health Canada told CBC News in an email.
"Again, Health Canada has no concerns at this time with the safety of non-polycarbonate bottles."
The Health Canada study also suggested the BPA may have come from machinery used in the manufacturing process.
But regardless of the origin of the contamination, the question of what should qualify as "BPA-free" is a murky one, says Dr. Tamara Galloway, a professor at the University of Exeter in Britain. She has been researching the effects of chemical and pollutant exposure on organisms.
"I think what [the Health Canada study] is suggesting is that we need greater clarity in labeling," Galloway told CBC News. "If we're going to say 'BPA-free,' what we need to do is define [what is] below the limits of detection or on the limits of detection."
Dr. Richard Stahlhut of the University of Rochester's Environmental Health Sciences Center agrees.
"To me, I would think that 'BPA-free' … should have a very specific meaning, and it should be a meaning … that's consistent with what you would expect," he said in an interview.
Health Canada says the concentration of BPA found in the non-polycarbonate bottles — most measured in the range of hundredths or thousands of a microgram per litres — are equivalent to the parts per trillion or parts per billion range. Health Canada says one part per billion "is equal to one drop of liquid diluted into 250 drums of water."
Methodology and results of Health Canada study:
- Health Canada filled polycarbonate and non-polycarbonate baby bottles with boiling water and, in separate trials, a solution of 10 per cent ethanol at 85 C.
- All the bottles were left to cool until the water reached a temperature of 60 C.
- After cooling, researchers measured the concentration of bisphenol A in the water and ethanol in four intervals: at 2 hours, 22 hours, 94 hours and 238 hours.
- The bottles filled with 10 per cent ethanol were also measured for bisphenol A at the same intervals.
- Among the non-polycarbonate bottles, Dr. Brown's bottles were shown to have the highest concentrations of bisphenol A migrating into water.
- Adiri-brand bottles were not tested with water, but leached trace amounts when tested with the ethanol solution.
- Green to Grow has publicly questioned health Canada's findings in media reports, with co-founder Shelley Aronoff telling the Canwest news service she didn't have faith in the results. She called for the test results to be independently validated.
- Dr. Brown's, whose award-winning Natural Flow bottle measured among the highest concentrations of bisphenol A, did not respond to several requests for comment.
"These tiny amounts are not harmful," Health Canada says.
Health Canada reacted similarly in May 2008 after testing detected low levels of the chemical bisphenol A in cans of tomato sauce and tins of apple juice.
"A preliminary examination of the results show that levels of BPA reported as migrating from canned food sources are very low, in the range of parts per billion [one billionth gram in a gram of food] and are consistent with levels of BPA reported in canned foods sold worldwide."
Similarities to hormone signaling
The problem with that reasoning, argues Stahlhut, is that hormones in the body operate at comparable concentration levels in the bloodstream. And animal studies in peer-reviewed journals have found that BPA may imitate estrogen and other hormones.
"Some of the signaling that is going on in our bodies, and especially in a developing fetus, are happening at parts per trillion levels," he says. Using Health Canada's criteria, hormonal levels in the body can be described as being present in "trace amounts," he adds.
"Unfortunately, the body operates at trace amounts."
But regulatory agencies like Health Canada or the U.S. Food and Drug Administration don't routinely test for exposure to chemicals at these minute levels, says Stahlhut, whose research focuses on how chemical exposures might contribute to obesity and diabetes epidemics.
"It's conceivable that the folks at Health Canada are right [about the BPA levels not being harmful]," says Stahlhut, who was the lead author of a January 2008 study suggesting BPA remains in the body for longer than was previous thought.
But it's hard to determine the veracity of the agency's judgment, he says, particularly as "five years ago, everybody would have told you that hundred times [those levels] would be fine."
Technology outpaces regulation
Bisphenol A has been manufactured in plastics since the early 1900s, and research into its effects on humans has only come about recently. It's an illustration of an all-too-familiar situation since the industrial revolution — technological advances have routinely outpaced our ability to regulate them.
Stahlhut says regulatory agencies only step in when there is really clear evidence a substance may cause harm. But it takes time to ensure absolute certainty.
Galloway echoes those concerns.
"One of the main issues is that it's very difficult to find one single study that's going to give you absolute certainty in anything, but those small incremental bits of evidence should be adding together to give you cause for concern," she says.
"I think we're looking at something which is giving a very small risk, but it's giving a very small risk for very large numbers of people — almost everybody in the population is exposed to this chemical."
Galloway was among the authors of a study published in September 2008 that examined BPA exposure in humans. The study, which included 1,455 U.S. adults, found that 90 per cent of participants had detectable levels of BPA in their urine.
Galloway and her colleagues said those with the highest levels of BPA concentrations in their urine had nearly three times the odds of cardiovascular disease, compared with participants with the lowest levels of BPA. The study also found people with high BPA levels had 2.4 times the odds of Type 2 diabetes in comparison with those with the lowest levels.
No need for hysteria
Despite her research, Galloway says she doesn't think a ban on bisphenol A is necessary. She says people can simply limit their exposure to the compound, and points to innovations in the manufacturing process that can drastically reduce BPA levels in polycarbonates.
And Galloway says there is at least some merit to the Health Canada findings.
"Anything that reduces our exposure to BPA has got to be a good thing. So although the … researchers are suggesting there may be still minute traces of bisphenol A associated with the end product, it's still got to be better to use that bottle than one that contains a high concentration of bisphenol A."
And Health Canada's increased scrutiny of bisphenol A since 2007 has prompted retailers like Wal-Mart Canada, Canadian Tire, Hudson's Bay Co, Sears Canada, and Rexall Pharmacies to pull products containing the compound from shelves.
Stahlhut says the current regulatory battles over what constitutes a safe level of bisphenol A isn't the main concern.
"The better lesson is we’ve been using this stuff for decades," says Stahlhut. "And people have been telling us it was safe for decades at levels way higher than this — and now that's in question."
Despite the delayed response of regulatory agencies, however, people can take it upon themselves to limit their exposure to potentially harmful chemicals, he says.
"I don't want people running around scared. What I want them to understand is that we're not nearly smart enough for the task we've created," Stahlhut says.
"If they're expecting people like me to protect them, they can expect me to be 20 years behind, and that's not a good place to be."