In a controlled experiment, volunteers’ blood pressure went up after they drank from a BPA-lined can.

Research on effects of Plastics

Several years ago, there was a flurry of research on the potential health effects of plastic. Studies suggested that one ingredient, bisphenol A (BPA), could interfere with hormonal activity. The chemical was originally used as a synthetic form of estrogen before it became common in plastics. Federal agencies agreed that BPA at normal exposure levels could be dangerous for infants, and they have banned BPA in products such as sippy cups. But they’ve tabled the question for adults. Americans continue to drink canned beverages and eat food from cans lined with BPA. BPA is found in the linings of most canned foods and most aluminum cans, including Coca-Cola products. Handling register receipts in stores is another common way people are exposed.

Effects of BPA

Now, a new study suggests that even small doses of BPA can significantly increase blood pressure in adults. Korean researchers gave study volunteers soy milk in glass jars and in BPA-lined cans and measured their blood pressure after drinking. By testing the same participants with both container types on different days, the study eliminated other potential differences in BPA exposure among the volunteers. Unlike observational studies, the controlled experiment showed that BPA directly caused the bump in blood pressure. “If you consume what’s in the can, it can increase the levels of BPA in your blood, and that can lead to an increase in blood pressure,” said Dr. Anthony DeMaria, a former president of the American College of Cardiology, who was not involved in this study. Participants — mostly women older than 60 — saw a 1600 percent spike in the amount of BPA in their urine after drinking from the can. Their systolic blood pressure was, on average, 4.5 mm Hg higher after they drank the canned beverage. The American Heart Association says that 120 mm Hg is the highest healthy systolic blood pressure, and an increase of 20 mm Hg over the long term doubles a person’s risk of heart disease. “This study’s claim that BPA, which is safely used in can linings to protect food and beverages from contamination, ‘may pose a substantial health risk’ is a gross overstatement of the findings, an incredible disservice to public health, and runs contrary to years of research by government scientists. The authors’ conclusions from this small-scale study significantly over-interpret the data measured in the study,” the group said.

Short-Term vs. Long-Term Risks

It’s important to note that the study only showed that BPA causes a temporary spike in blood pressure. It’s long-term high blood pressure, which puts more strain on the walls of veins and arteries, which generally concerns doctors. But it will take a different study design to determine whether BPA has long-term effects on blood pressure. While temporary spikes in blood pressure could bring on a stroke or heart attack in at-risk patients, 4.5 mm Hg would probably not be enough to do so in healthy people, DeMaria said. However, some people could potentially have a much greater response than others. The study findings are persuasive enough that DeMaria thinks patients with high blood pressure might consider drinking out of something other than BPA-lined cans. Perhaps even people who don’t have high blood pressure should do the same. “On many days, I drink more than three cans of soda and I’m thinking to myself that this may not be a very smart thing to do,” said DeMaria, now a professor of medicine at the University of California, San Diego, School of Medicine.

Are There Healthier Alternatives?

The Korean study and others like it will contribute to the Food and Drug Administration’s evaluation of BPA, and could eventually prompt the agency to ban it. In the meantime, the Center for Environmental Health in Oakland, California, which lobbies against BPA and other harmful chemicals, suggests consumers find old-school alternatives to BPA. “When possible, stick with materials that people have been using a long time,” said research director Caroline Cox. Glass jars and juice boxes can substitute for cans, for example. New BPA-free plastics may not be any safer than BPA, early research suggests. It can be easy to get “frustrated and depressed every time you find out more about some toxic chemical,” Cox said. She encourages people just to “take the simple steps that they can take.”