Evidence is mounting that a chemical in
plastic may be risky in the small amounts that seep from
bottles and food packaging, according to a report to be
published this week in a scientific journal.
Authors of the report, who reviewed more than 100 studies,
urged the Environmental Protection Agency to re-evaluate the
risks of bisphenol A and consider restricting its use.
Bisphenol A, or BPA, has been detected in nearly all human
bodies tested in the United States. It is a key building block
in the manufacture of hard, clear, polycarbonate plastics,
including baby bottles, water bottles and other food and
beverage containers. The chemical can leak from plastic,
especially when containers are heated, cleaned with harsh
detergents or exposed to acidic foods or drinks.
The plastics chemical is the focus of one of the
most-contentious debates involving industrial compounds that
can mimic sex hormones. Toxicologists say exposure to man-made
hormones skews the developing reproductive systems and brains
of newborn animals, and could be having the same effects on
human fetuses and young children.
Since the late 1990s, some experiments have found no effects
at the doses of BPA that people are exposed to, while others
suggest that it is estrogenic, blocks testosterone and harms
lab animals at low doses. Plastics-industry representatives
say the trace amounts that migrate from some products pose no
danger and are far below safety thresholds set by the EPA and
other agencies.
In the new report, to be published online tomorrow in
Environmental Health Perspectives, scientists Frederick vom
Saal and Claude Hughes say that, as of December, 115 studies
have been published examining low doses of the chemical, and
94 found harmful effects.
In an interview yesterday, vom Saal, a reproductive biologist
at University of Missouri, Columbia, said there is now an
"overwhelming weight of evidence" that the plastics compound
is harmful.
"This is a snowball running down a hill, where the evidence is
accumulating at a faster and faster rate," vom Saal said. "You
can't open a scientific journal related to sex hormones and
not read an article that would just floor you about this
chemical. ... The chemical industry's position that this is a
weak chemical has been proven totally false. This is a
phenomenally potent chemical as a sex hormone."
In their study, vom Saal and Hughes suggest an explanation for
conflicting results of studies: 100 percent of the 11 funded
by chemical companies found no risk, while 90 percent of the
104 government-funded, non-industry studies reported harmful
effects.
Steven Hentges, executive director of the polycarbonate
business unit of the American Plastics Council, said yesterday
that the new report lists numbers of studies and pieces of
data without analyzing them to determine their strengths or
weaknesses and relevance to human beings.
"The sum of weak evidence does not make strong evidence,"
Hentges said. "If you look at all the evidence together, it
supports our conclusion that BPA is not a risk to human health
at the very low levels people are exposed to. This paper does
not change that conclusion. It has an opinion, not a
scientific conclusion."
There has been an escalating battle between vom Saal and the
plastics industry since 1997, when vom Saal was the first to
reveal low-dose effects in mice exposed to BPA. His discovery
triggered a rash of new scientific studies by industry and
government.
The chemical, used in polycarbonate plastics manufactured for
half a century, is not subject to any bans.
Polycarbonate plastics, useful in items such as baby bottles
because they are durable, lightweight and shatter-resistant,
cannot be made without BPA.
