Manufactures use a chemical called bisphenol-A, or BPA, to make plastic bottles, thermal papers like receipts and as a lining in canned goods. The chemical has come under scrutiny because studies have shown that it's an endocrine disruptor, interfering with the activity of hormones in the body like estrogen. And animals studies have linked it to long-term health problems such as altered sexual development and brain impairments.
It has been generally assumed, though, that the health effects of BPA only become apparent after long-term, continuous exposure, and that they are most prominent or relevant in developing fetuses or young children, says Laura Vandenberg, who studies endocrine disruptors at the University of Massachusetts-Amherst.
But a new study looked at the health impacts on adults drinking a liquid from bottles lined with BPA, and found that the chemical not only made it into their bodies but seems to have caused a significant increase in blood pressure.
In the study, published in the journal Hypertension, researchers randomly gave 60 participants soy milk from a BPA-lined can or a coating-free glass bottle (sans BPA) on different occasions. Some participants drank two cans, some drank two bottles, and some drank one of each. Two hours later, the scientists measured their blood pressure and vital signs, and sampled their urine to see how much BPA came out.
They found that after drinking from two BPA-laden cans, people's urine contained 16 times more of the chemical than if they had imbibed the milk in the glass bottles. This shows that BPA does indeed make its way from the lining into the food, says study author Yun-Chul Hong, a physician and researcher at Seoul National University College of Medicine in South Korea.
More importantly, scientists found that those who drank two BPA-lined cans subsequently registered significantly higher blood pressure than other participants, Hong adds. Specifically, the systolic blood pressure was increased by 5 mmHg in those who drank from the cans. Systolic is the "top number" of a blood pressure reading, and it measures the pressure in the arteries when the heart beats.
This is concerning, Hong says, "because hypertension, or elevated blood pressure, is a well-known risk factor for heart disease." The study, he adds, "suggests BPA exposure may increase risk of heart disease."
Researchers don't know what the causal mechanism might be. But they suspect it has to do with BPA's effect on estrogen receptors; estrogen is involved in regulating blood pressure, Hong says.
"I must say, I was surprised to see that exposures to beverages containing BPA would have a measurable effect on a health outcome like blood pressure," says Vandenberg, who wasn't involved in the study.
The study does have some limitations, though, as it was relatively small (60 participants) and examined women, half of whom had high blood pressure to begin with. This might limit generalizations to the rest of the population, but the results are nevertheless "interesting and alarming" and "should definitely be repeated with a broader group of volunteers," Vandenberg says.
"This study does reinforce growing concerns about the ubiquitous presence of this chemical and whether we need to rethink many of the applications in which it is used," says Patricia Hunt, an expert on BPA at Washington State University who wasn't involved in the research. "It's rather like lining the inside of food and beverage containers with pharmaceuticals, isn't it?"
Uncommon Knowledge
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