Here at Can Science News, we write a lot about the benefits of canned fruits, vegetables and fish:
- They’re just as healthy as their fresh counterparts
- They cost less than fresh produce and fish
- Cans are recyclable
But some people still have one big worry when it comes to canned goods — BPA, a compound used in the lining of cans to preserve the food inside. They’ve heard or read that BPA can cause a variety of health problems, including diabetes, obesity, breast cancer, heart disease and behavioral abnormalities.
It’s time to stop worrying.
A recently published book, “Getting Risk Right: Understanding the Science of Elusive Health Risks,” argues that consumers have no reason to fear BPA. We chatted with the author, Geoffrey Kabat, a senior epidemiologist at the Albert Einstein College of Medicine of Yeshiva University and Montefiore Medical Center, about how the BPA hysteria developed, the science and controversies behind the studies, and regulatory agencies’ stance on BPA.
Q: In your book, you explain how the public came to fear BPA. Can you give us a quick summary?
In the late 1990s, there were only 10 academic studies about BPA. In 2005, there were 65. By 2013, there were 199. The media reported on these studies, and the public panicked that BPA could leach out of plastic bottles, cans and sippy cups and into the body. But the scientists looking at these studies don’t all agree on the findings. Some believe BPA causes problems, but many others don’t. One group wants more regulation and others say there is no need.
Q: You fall into the latter camp. What evidence is there that people don’t need to fear BPA in cans?
Not all science is created equal. Some of the studies that put BPA in the public eye were really poorly done. In my book, I talk about how a fundamental principle of toxicology is that, “The dose makes the poison.” The higher the dose to which humans or test animals are exposed, the higher the likelihood of observing an effect. For example, the more cigarettes you smoke each day, the greater the risk of lung cancer and other diseases caused by smoking.
We know that exposure to BPA in the U.S. population is very low, as measured in urine. The best BPA studies show that even when humans are exposed to high levels of BPA, from food, the compound is not detected in the blood. More than 99 percent of ingested BPA is metabolized and excreted by humans in the urine. For example, a few years ago, Justin Teeguarden of the Pacific Northwest National Laboratory conducted a study in which 20 volunteers ate almost nothing but canned foods for a day. That diet put them in the 95th percentile for BPA exposure in the United States. But BPA wasn’t detectable in any of the 320 sensitive blood samples taken over that 24-hour period. It was absorbed or excreted.
Q: You make it sound so simple. Why is there such disagreement among scientists and academics?
Some scientists are already wedded to a conclusion before they start a study. When you look at the studies conducted by those who believe that BPA is bad, the first thing you see is that there’s little concern to the overall quality of their methodology. There’s little or no attention paid to experimental design, adequate sample size, appropriateness of the experimental system, or replications of results. Secondly, they tend to cite the work of other like-minded scientists. There’s almost no recognition of work from scientists who don’t agree. Third, they don’t tend to recognize that other factors, like maternal smoking or use of medications, might play a role in the results.
Here’s an example of a bad study. In 1997, two scientists gave BPA in drinking water to pregnant mice during the prenatal and immediate postnatal periods. To study the effects on prostate weight in male offspring, they randomly selected one adult male from each of seven litters. But studies that have tried to replicate this one show that prostate weight varies dramatically within each litter. No one has ever been able to replicate the original study, but people who believe BPA is bad continue to cite the original study as important evidence.
Teeguarden of the Pacific Northwest National Laboratory has found that studies that seem to conclude BPA is bad could be flawed because the blood samples are contaminated by BPA in medical devices, like intravenous lines.
Do you worry about canned goods for any other reasons, besides BPA?
No. If anything, I hate to see the industry cave and react by making cans free of BPA. Sixty years of literature shows that BPA is an effective deterrent against botulism and other illnesses.
It’s important to note that many national health agencies, including the U.S. FDA, the EPA, Health Canada, the European Food Safety Authority, Food Standards Australia New Zealand and the German Federal Institute for Risk Assessment have thoroughly examined the issue and have found BPA to be safe at levels to which the general population is exposed.
BPA shouldn’t be an issue anymore. We should really be concerned about the real dangers, such as those associated with smoking cigarettes, texting while driving and obesity.