In a new study, researchers on Mayo Clinic’s Florida campus found that exposing female mice to the chemical bisphenol A (BPA) increased their risk of myocarditis, a rare inflammatory heart disease usually triggered by a virus.

BPA is commonly found in plastic food and beverage containers; people can ingest BPA when it seeps into what they eat and drink. The Food and Drug Administration states that BPA is safe at the low levels that occur in these exposures. But some concerns remain: for example, people with higher exposures such as workers in plastic-related manufacturing jobs or sales clerks handling BPA-coated receipts could be at risk of adverse effects to the endocrine system.

“We began this study because we know that sex hormones influence the development of myocarditis, so we wanted to explore whether an endocrine disruptor such as BPA could play a role,” says principal investigator DeLisa Fairweather, Ph.D., a Mayo Clinic cardiovascular researcher.

First author Katelyn Bruno, Ph.D., and senior author DeLisa Fairweather, Ph.D.

In the main experiment, Mayo researchers and collaborators at Johns Hopkins added a human-relevant dose of BPA to the drinking water of female mice for two weeks. Control mice were given drinking water without BPA added. Compared to controls, the BPA-exposed animals experienced an increased incidence of myocarditis after exposure to a viral infection capable of inducing the disease. The scientists attribute this finding to BPA’s ability to alter estrogen receptors.

Dr. Fairweather and team also found evidence of an activated immune response in BPA-exposed animals, namely, an increase in cardiac mast cells, which are associated with cardiovascular disease.

In a separate experiment, the researchers compared female mice housed in traditional plastic caging with plastic water bottles, to animals housed in glass cages with glass water bottles. In this portion of their study, they did not add BPA to any animals’ drinking water. The investigators found that animals in plastic dwellings experienced increased mast cell activation compared to those in glass houses. “This suggests that contact with plastic is all that’s needed to induce a response,” says Mayo cardiovascular researcher and the paper’s lead author, Katelyn Bruno, Ph.D.

“Mast cell activation like the kind observed in this study is linked to a variety of major conditions including additional types of heart disease, autoimmune disease, and more,” says Dr. Fairweather. “It’s possible that plastic exposure could play a role in all of these diseases.”

The authors note that further work is needed to confirm their results in humans. As a next step, Dr. Fairweather and colleagues hope to test whether BPA levels in the blood of myocarditis patients correlate with signs of heart failure. They are also investigating the effect of BPA exposure in male mice.

In addition, because of the ability for viruses to cause myocarditis, the researchers say that elevated BPA exposure just prior to viral infection – as opposed to lifetime exposure – may be important to explore.

The study was published in Frontiers in Endocrinology. It received funding from the National Institutes of Health and Mayo Clinic Center for Regenerative Medicine.

Dr. Fairweather's Translational Cardiovascular Disease Research lab works to understand the beginnings of diseases characterized by sex differences. They hope to discover new therapies and diagnostic techniques for patients with myocarditis and other cardiovascular and autoimmune diseases.