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The Bisphenol-A Debate: A Suspect Chemical in Plastic Bottles and
Cans
by Catherine Zandonella, M.P.H
If you are like many readers of The Green Guide, you try and choose
foods that are as free as possible of harmful chemicals such as
pesticides. But if you consume canned soups, beans and soft drinks,
organic or not, you also may be swallowing residues of a
controversial chemical called bisphenol A (BPA) that can leak out of
the can linings into your food. Nearly all can liners contain BPA,
says Geoff Cullen, director of government relations at the Can
Manufacturers Institute. BPA has also been found to migrate, under
some conditions, from polycarbonate plastic water bottles.
Depending on whom you talk to, BPA is either perfectly safe or a
dangerous health risk. The plastics industry says it is harmless,
but a growing number of scientists are concluding, from some animal
tests, that exposure to BPA in the womb raises the risk of certain
cancers, hampers fertility and could contribute to childhood
behavioral problems such as hyperactivity.
According to its critics, BPA mimics naturally occurring estrogen, a
hormone that is part of the endocrine system, the body's finely
tuned messaging service. "These hormones control the development of
the brain, the reproductive system and many other systems in the
developing fetus," says Frederick vom Saal, Ph.D., a developmental
biologist at the University of Missouri. Endocrine-disruptin g
chemicals can duplicate, block or exaggerate hormonal
responses. "The most harm is to the unborn or newborn child," vom
Saal says.
Plastic water and baby bottles, food and beverage can linings and
dental sealants are the most commonly encountered uses of this
chemical. Unfortunately, it doesn't stay put. BPA has been found to
leach from bottles into babies' milk or formula; it migrates from
can liners into foods and soda and from epoxy resin-lined vats into
wine; and it is found in the mouths of people who've recently had
their teeth sealed. Ninety-five percent of Americans were found to
have the chemical in their urine in a 2004 biomonitoring study by
the Centers for Disease Control and Prevention (CDC).
Plastics manufacturers do not deny that BPA is found widely in
canned foods and beverages and is routinely ingested. They part ways
with vom Saal and other scientists over the human health risks. The
levels that leach into food are well below the safety thresholds set
by the Environmental Protection Agency (EPA), and the plastics
industry website, Bisphenol-A. org, says the chemical is completely
safe unless you ingest 1,300 pounds of canned and bottled food
daily. In other words, even a canned-food addict will likely ingest
500 times less BPA than the danger level set by the EPA and 100
times less than the standard set by the European Commission
Scientific Committee on Food. And common sense tells us that if
higher doses are safe, then lower doses must be too, right?
Not necessarily, says vom Saal, who notes that these safety levels
are based on 1980s toxicity studies in rats. In those studies,
conducted at relatively high doses, the only sign of toxicity was
reduced body weight. However, when it comes to hormone disruption,
different doses can activate or suppress different genes, vom Saal
explains. "That's why early toxicity studies found that the high
doses were safe. The studies didn't look at the low doses that are
now proving to cause a myriad of harmful effects in animals,
including chromosomal damage in female egg cells and an increase in
embryonic death in mice. A follow-up to this is a study indicating a
relationship of BPA blood levels to miscarriages in Japanese women,"
he says.
BPA was thrust into the spotlight by a laboratory mishap. In August
1998, geneticist Patricia Hunt, Ph.D., now at Washington State
University in Pullman, noticed that chromosomal errors in the mouse
cells she was studying had shot up—from 1 or 2 percent to 40
percent, as published in the April 2003 Current Biology. Hunt traced
the effect to polycarbonate cages and water bottles that had been
washed with a harsh detergent. When her team replaced all the caging
materials with non-polycarbonate plastics, the cell division
returned to normal.
But not all scientists think BPA is capable of doing such harm to
humans. Some deny that BPA disrupts hormones. A study funded by the
Society of the Plastics Industry and published in the July 2002
Toxicological Sciences that explored the effects of low doses on
three generations of rats found no effect on reproduction or
development. "If you look at all the data together, you don't find a
consistent pattern of effects that are characteristic of an
estrogenic chemical," says Steven G. Hentges, Ph.D., executive
director of the Polycarbonate Business Unit at the American Plastics
Council. Others argue that rodent studies such as Hunt's are not
relevant to humans. A study published in the October 2002 Chemical
Research in Toxicology of human volunteers found that a human body
neutralizes and excretes BPA far more rapidly than a rat's body
does.
So far, regulatory agencies agree. "Based on all the evidence
available at this time, the FDA sees no reason to change its long-
held position that current [BPA] uses with food are safe," George
Pauli, Ph.D., associate director for science and policy at the FDA's
Office of Food Additive Safety, wrote in a November 28, 2005,
letter.
Vom Saal counters that the studies showing BPA is safe
are "profoundly flawed and in some cases exhibit outright fraud."
Last year, he published a paper showing that 100 percent of the
industry-funded studies, 11 in all, found no harmful effects from
BPA, while 90 percent of government-funded low-dose studies, 104 in
number, found harmful effects. "Among people who have actually read
this literature there is no debate, just an illusion of
controversy, " he says.
Meanwhile, new studies continue to reveal the potential for harm. A
January 2006 study indicates that BPA may enhance the risk of
developing Type II diabetes. Angel Nadal, Ph.D., and his team at the
University of Miguel Hernández de Elche in Alicante, Spain, found
that BPA altered the function of mouse pancreatic cells, which
produce insulin. Unhealthy diet, a lack of exercise and a genetic
predisposition are the main factors in triggering diabetes, says
Nadal. "However, our feeling is that these factors could be
exacerbated by the presence of environmental pollutants such as
bisphenol A."
Human studies might settle the controversy over BPA, but so far they
have been too limited to prove much. One study linked women with
ovarian disfunction to elevated blood levels of BPA, and another
found that blood levels of BPA were three times higher in women
who'd suffered recurrent miscarriages than in women with successful
pregnancies. While intriguing, these studies were from a small
sample group. A more definitive result could be gained from a large-
scale study to track people's exposures, follow them for years and
look for health effects. The National Toxicology Program is planning
a future evaulation of BPA.
Some scientists urge that action be taken now, regardless. "Science
is not in the business of demonstrating anything beyond a shadow of
a doubt," says Ana Soto, M.D., a professor and researcher at Tufts
University School of Medicine in Boston, who has found that BPA
alters mammary-gland development in mice. "We cannot wait that long
to discover whether this chemical is harming human reproduction and
development. " However, because government agencies remain
unconcerned, it is unlikely that BPA will disappear from consumer
products anytime soon. A California bill to ban BPA in baby toys and
feeding products was defeated in January. In the meantime, see the
sidebar for what you can do to reduce your exposure.
8 Ways to Avoid Harmful Chemicals in Plastics and Cans
1. If you already own polycarbonate bottles, including the Nalgene
bottles popular on college campuses, labeled #7 on the bottom, wash
them by hand with mild dishwashing soap, not in the dishwasher, to
avoid degrading the plastic and increasing leaching of BPA
(see "Picnic Perfect Plastics").
2. Even plastic does not last forever. Look for cracks or cloudiness
on your reusable clear plastic bottles. See The Green Guide's
survey, "A Nalgene Bottle Poll."
3. Use glass baby bottles or plastic bag inserts, which are made of
polyethyelene, or switch to polypropylene bottles that are labeled
#5 and come in colors or are milky rather than clear.
4. Choose soups, milk and soy milk packaged in cardboard "brick"
cartons, by Tetra Pak and SIG Combibloc, which are made of safer
layers of aluminum and polyethylene (#2) and also recyclable.
5. Choose canned foods from makers who don't use BPA, such as Eden
Foods (www.edenfoods. com), which sells certified organic canned
beans and other foods.
6. Eat fresh foods in season and save the canned foods for
convenience or emergencies. The exception is some canned fruit such
as that found in smaller fruit-cocktail cans, which do not require a
liner, according to the Can Manufacturers Institute.
7. Buy or can your own fruits and vegetables in safe glass jars. For
more, see Amy's Green Kitchen "In a Summer Pickle".
8. Some wines have been found to contain up to six times the BPA of
canned foods. While most wines probably don't, it's another good
reason to drink in moderation.
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