Five years ago, U.S. environmental officials launched what they called
an "unprecedented" research program examining the health effects of
bisphenol A, used in many consumer products for decades.
The National Institute of Environmental Health Sciences pledged $30
million, and many researchers came up with additional funding - leading
to a stream of studies that are now reaching completion.
The studies have raised more suspicions, but "I don't think we have all
the answers yet," said NIEHS director Linda Birnbaum.
Other researchers and health advocates say we may be reaching a tipping
point, with enough evidence of BPA's harmful effects emerging to
persuade regulators to act.
Industry, meanwhile, points to other studies that it says prove
bisphenol A, commonly referred to as BPA, is safe.
BPA is one of the most common chemicals produced worldwide. Among many
other products, it is used in many plastic food and beverage containers
and in the linings of metal food cans. It also is used in paper used for
some receipts.
What's troubling is that it is an "endocrine disruptor," meaning it can
interfere with human hormonal systems. Specifically, it mimics estrogen.
It has been associated with many health problems, including infertility,
weight gain, behavioral changes, early-onset puberty, cardiovascular
effects, and diabetes, according to NIEHS.
One recent study found a link between early exposure to BPA and later
prostate cancer. The study was considered especially important because
it used not animal cells, but stem cells from human prostate tissue,
obtained from organ donors.
Implanted into mice, the cells grew into prostatelike glands. The mice
were fed BPA, then were given estrogen in amounts to mimic the increased
levels men have as they age.
The BPA-exposed mice proved far more likely to get cancerous lesions
than others that were not exposed.
"We found that early life exposure to BPA . . . changed the memory of
the prostate cells, so that when they saw estrogen later, they were more
sensitive," said Gail S. Prins, a University of Illinois at Chicago
physiologist who led the study. "It reprogrammed the cells. It altered
their memory."
Evidence of BPA's harms "just keeps accumulating," Prins said, showing
"rather strongly that previous concerns are, in fact, real, and they're
applicable to humans."
Another recent study, by Leonardo Trasande, an environmental medicine
expert at the New York University School of Medicine, quantified the
social costs of childhood obesity and adult coronary heart disease
attributable to BPA exposure in the U.S. He concluded that limiting its
use could provide economic benefits of $1.74 billion a year.
The American Chemistry Council's Steve Hentges, who leads its BPA group,
disputed the study's validity, saying no cause and effect between BPA
and obesity or heart disease has been proven.
"And the author completely disregards the significant economic and
public health benefits BPA delivers for a range of things from the
safety and integrity of packaged foods to high-performance sports
equipment and auto parts," he said.
He also noted that in its most recent update on BPA, in 2013, the U.S.
Food and Drug Administration "answers the question 'Is BPA safe?' with
one word: 'Yes.' "
The FDA also says it will continue its review of BPA. Last March, the
agency ruled that BPA could no longer be used in baby bottles and sippy
cups - largely a formality, since most manufacturers had already stopped
doing so.
Meanwhile, legislation to limit the use of BPA has been introduced in
Pennsylvania and New Jersey.
Many companies have begun to substitute a different chemical, bisphenol
S, for BPA.
But Sarah Vogel, director of the health program at the nonprofit
Environmental Defense Fund and author of Is It Safe?, a new book about
BPA, said the structure of the new chemical is "pretty darn close" to
that of BPA, and that it may even be more estrogenic.
The new chemical troubles Birnbaum, too. "This is a big issue we have
with many chemical substitutions," she said. "We move from one chemical
where we might have concern, to another chemical where we have very
little data."
http://www.philly.com/philly/news/science/20140202_More_evidence_that_BPA_is_harmful.html
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