A Chemical Found in Most Consumer Products May Cause Heart Disease in Women

A study released this week by researchers at the University of Cincinnati says that exposure to bisphenol A may increase heart disease in women.

Bisphenol A (BPA) is the chemical building block of polycarbonate plastics and is used in countless consumer products including food and beverage containers, kitchen appliances, electronics, and packaging and is used to make resins that line food and drink cans.

Research by Scott Belcher and colleagues in the university's department of pharmacology and cell biophysics has found that environmentally available levels of BPA -- a synthetic chemical known to mimic the behavior of estrogen -- can disrupt normal heart muscle function and prompt arrhythmia or irregular heartbeat.

BPA has come under increasing scrutiny by medical researchers for its endocrine-hormone-disrupting potential -- effects that include interference with reproductive, egg and fat cell development, as well as with thyroid hormone and neurological functions. The chemical has also been linked to conditions that can prompt obesity and diabetes.

Additional cause for concern is the fact that these adverse effects can occur at very low levels of exposure.

"Levels of bisphenol A identified in human blood that would be in direct contact with the heart" can produce the effects seen in our research, said Belcher, speaking from Washington, where this research was presented at the June 10-13 Endocrine Society annual meeting.

While it creates plastics so durable they are used in sports gear, motor vehicles, shatterproof lenses as well as in baby bottles and toddlers sippy cups, the chemical can leach from finished products. These plastics and resins are so widely used that researchers studying the chemical describe BPA as ubiquitous. And although BPA does not last long in the environment or the human body, because it is so prevalent, current exposure in the U.S. is considered virtually continuous.

Monitoring by the U.S. Centers for Disease Control and Prevention (CDC) has found BPA in nearly 95 percent of the Americans tested. A recent study by Health Canada found BPA in 96 percent of the canned soft drinks it tested -- a study that covered 84 percent of all soft drinks sold in Canada -- at levels equivalent to 500 times what are considered normal estrogen levels.

Belcher's study showed that environmentally relevant, low levels of BPA can interfere with the genetic receptors that help regulate cardiac muscles, resulting in an increased frequency of irregular heartbeat. As an estrogenic compound, explains Belcher, the BPA interferes with how the heart muscle cells process calcium, a key factor in maintaining normal, healthy heartbeat. Due the specific ways in which the female body responds to estrogenic substances, this effect occurred in females rather than males.

One in three women in the U.S. suffer from cardiovascular disease, and women account for over 50 percent of the U.S. deaths from heart attack, so this finding could have wide ramifications. 

According to the American Heart Association, women have a higher rate of death from a repeat -- rather than first -- heart attack, making any factors that could increase the risk of subsequent heart attack of particular concern.

Thus far, the adverse impacts of BPA on cardiac muscle cells have been seen in cells isolated from rat and mouse hearts. But Belcher says the genetic mechanisms affected should work the same way in the human heart. A statement on endocrine-disruption chemicals -- such as BPA -- just released by the Endocrine Society notes that the way these chemicals work is comparable in wildlife and in humans and in both live-animal and cell-culture experiments. Belcher's group is in the process of looking at cells isolated from human heart transplant samples.