foodconsumer.org: Studies: BPA may cause heart problems in women

Studies: BPA may cause heart problems in women
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admin on 13/06/2009 20:51:00
 
Saturday June 13, 2009 (foodconsumer.org) -- Bisphenol A (BPA) may be harmful
for the heart, particularly in women, according to several studies presented in
Washington, D.C. at ENDO 09, the Endocrine Society's annual meeting.
Studies suggest that people with cardiovascular disease have higher levels of
BPA in their urine.
One study led by Dr. Scott Belcher, of the department of pharmacology and cell
biophysics at the University of Cincinnati, found exposure to BPA and or
estrogen causes abnormal cardiac activity in female rats and mice.
Researchers also found that estrogen receptors in heart muscle cells are
responsible for the effect. BPA, officially recognized as an environmental
pollutant, is estrogenic and can interact with the receptors.
Previous studies suggest exposure to BPA may cause problems with development of
the reproductive system and the brain among other things.
"We had reason to believe that harmful cardiovascular affects can be added to
the list," said Belcher, according to a UC press release.
BPA is used to make hard polycarbonate plastic, such as for baby bottles,
refillable water bottles and food containers, as well as to make the linings of
metal food cans. It has been linked to an increased risk of neurological
defects, diabetes and breast and prostate cancers.
For the current study, Belcher and his team exposed cardiac cells isolated from
rat or mouse hearts to BPA, and or estrogen, and found both caused abnormal
activity of cardiac muscle cells in women, but not men.
Additional studies revealed that the change caused improper beating or an
increased frequency of arrhythmias, or heartbeat irregularities in the female
heart.
"Low doses of BPA markedly increased the frequency of arrhythmic events,"
Belcher said. "The effect of BPA on these cardiac arrhythmias was amplified when
exposed to estradiol, the major estrogen hormone in humans."
The researchers used cellular imaging techniques to investigate the mechanism
underlying this harmful effects and found that BPA, and or estrogen, rapidly
stimulated contraction by altering control of the concentrations of free
intracellular calcium in female heart muscle cells.
"BPA's presence increased the frequency of calcium 'sparks' from the
sarcoplasmic reticulum—the part of the cardiac muscle that stores and releases
calcium ions—indicating spontaneous release or 'leak' that's likely causing
the heart arrhythmias and may have other harmful actions, especially following
heart attack," stated Belcher.
"These studies have identified new and important potential cardiac risks
associated with BPA exposure that may be especially important for women's heart
health," he said.
Another study led by Dr. Hugh Taylor, professor and chief of the reproductive
endocrinology section at Yale University School of Medicine, explained that
exposure to BPA early in pregnancy may cause a fertility defect in the
offspring.
Specifically, Taylor and colleagues found mice born to mothers that were
exposed to a low dose of BPA in early stages of pregnancy (9 to 16 days) had
their uterine function changed.
They found that BPA exposure during pregnancy affected a gene known as HOXA10
that is responsible for uterine development and fertility in both mice and
humans. The exposure resulted in a permanent increase in estrogen sensitivity.
"We don't know what a safe level of BPA is, so pregnant women should avoid BPA
exposure," Taylor said. "There is nothing to lose by avoiding items made with
BPA -- and maybe a lot to gain."
(David Liu and edited by Sheilah Downey)