Is It Safe to Heat Food in Plastic?
From Good Housekeeping
To get behind the hype, Good Housekeeping tested 31
containers, lids, bags, wraps, and liners. What we found was reassuring but
to really protect your family, there's more you need to know.
My kitchen is probably similar to yours filled with
products that help me get dinner on the table fast. I have cans of beans and
tomato paste on my pantry shelves. In the fridge, there's usually a collection
of leftovers last night's lasagna, some barbecued chicken the kids didn't
finish in dishes covered with plastic wrap, ready to eat after a zap in the
microwave. I sometimes buy food and drinks in plastic containers, I've been
known to chop on a plastic cutting board, and I carry water around in a plastic
bottle. So I've grown increasingly alarmed over news stories on plastics in
recent months. First, reports quoted scientists and environmental groups saying
that the same containers and wraps that have made life so convenient may
contain chemicals that can pose dangers to health: bisphenol A (BPA), which,
among its many roles, is used to make a type of hard plastic, and certain
phthalates (pronounced THAL-ates), a wide range of chemicals that, among their
many uses, soften plastic.
Quickly, as the media coverage intensified, manufacturers
and retailers took up the charge: Last spring, just when I was packing my kids'
lunches with Nalgene water bottles, the company announced it was phasing out
bottles made with BPA. Many retailers have decided to stop selling toys and
other kids' products with BPA and phthalates, and a growing list of companies,
including P&G and Nike, have been taking phthalates out of everything from
beauty products to sneakers.
Lawmakers have jumped into action, too. California,
Washington State, and Vermont, for example, have limited the allowable amount
of phthalates in children's products, and Congress added a partial phthalate
ban to its new consumer-protection law, passed in August. But while legislators
have been scurrying to pass protective laws, the federal agencies entrusted
with overseeing our health have been slow to respond and maddeningly vague
when they do. In 2007, an expert panel was commissioned by the National
Toxicology Program at the National Institute of Environmental Health Sciences,
which evaluates chemicals for safety. The panel issued the reassuring statement
that it had "minimal concern" about most human health effects from
BPA, though it acknowledged "some concern for neural and behavioral
effects in fetuses, infants, and children at current human exposure." But
after it was reported that a consulting group used by the panel had ties to the
industry, NTP scientists revised these findings, raising the level of concern.
It's enough to make a mom toss up her hands and toss out
all the plastic in the house.
Or maybe just in the kitchen? The biggest worry has been
over BPA and phthalates getting into food and drinks (and into toys small
children chew on). Most of us aren't eager to sacrifice the ease and
cleanliness of plastic. But we need more definitive answers than the
authorities have been giving us. That's why the Good Housekeeping Research
Institute undertook testing of widely available storage containers, bags,
wraps, frozen-entrée trays, and slow-cooker liners to see if these chemicals
were, in fact, migrating into food a kind of real-world investigation that
would help moms decide just how cautious they need to be.
If the chemicals are getting into food, we need to
understand what that means for our health. And if they're not, we'd like to
stop hyperventilating. The GHRI tests turned up good news. But a review of
additional recent research yielded other unsettling questions, particularly
about hormonally related ills. Both the tests and the research point to the
smartest ways to keep our families safe.
Where Chemicals Lurk
Many hadn't heard of bisphenol A before it grabbed the
headlines earlier this year, but the chemical has been in our lives for
decades. Not only is it used to make hard-plastic food containers and baby
bottles, but it's also found in eyeglass lenses, compact discs, electronics,
and a slew of other common, everyday items. Used in the plastic-like coating
that lines food and beverage cans, BPA helps buffer the contents from cans'
corrosive metals and extends the products' shelf lives. And when these
containers and cans and bottles and CD cases end up in landfills, BPA can leach
into rivers and streams, possibly reentering our homes and bodies through
tap water. The chemical has also been found in household dust, where it settles
as plastic products break down and scatter microscopic particles. We all touch
it and breathe it in; crawling babies, who put everything in their mouths, may
absorb even more.
But our highest exposure comes from our daily diet, reports
the National Toxicology Program. Molecules of BPA can migrate from containers into
food, especially, say experts, when the containers are heated and the foods are
acidic (like tomatoes) or fatty (like gravy). That's why GHRI used those two
food types for its tests plus, these items are commonly heated in a
microwave. Just as a mom might prepare her family's dinner in her kitchen, GHRI
scientists, working with chemists at an independent lab, heated samples of Old
World Style Ragϊ Traditional Smooth Pasta Sauce and Heinz Home Style Gravy
Savory Beef in the microwave in two different widely available storage
containers and in glass bowls covered with a commonly used plastic wrap. Why
these? In pretesting, low levels of BPA had turned up in the two containers
Rubbermaid Easy Find Lids and Rubbermaid Premier. One plastic wrap, Glad Press
'n Seal, had tested positive for low levels of both phthalates and BPA. (A
fourth item, Glad Storage Gallon Zipper Bags, was found to contain low levels
of BPA, but was eliminated from food testing since it's unlikely that anyone
would use the bags for heating liquid foods like pasta sauce or gravy.)
The results: When food was heated in these containers in the
microwave (or, in the case of Press 'n Seal, in a glass bowl covered with the
wrap prior to microwaving), all three suspect products passed: "No detectable
amounts" (to use the scientific phrase) of BPA or phthalates wound up in
either the tomato sauce or the gravy.
While this is terrific news, there's more you should
understand. For one thing, we know we have these chemicals in our bodies, and
they're getting there somehow. Indeed, nearly every American has BPA coursing
through his or her veins, according to data gathered in 2003-04 by the Centers
for Disease Control and Prevention and children have the highest levels of
all. The FDA estimates that adult Americans consume, on average, a cumulative
11 micrograms of BPA per day through diet mostly from the liners in canned
foods, say several scientific groups. Is that level a lot? Is it safe? No one
really knows yet, but "we're concerned about how much exposure there is to
this chemical and possible health repercussions," says Anila Jacob, M.D.,
a physician and senior scientist for the Environmental Working Group (EWG), a
nonprofit watchdog scientific organization.
Nor does anyone know for sure whether BPA accumulates in
humans over time, though most scientists believe adults process it quickly in
as little as a day. However, the fact that so many of us have the compound in
our bodies means that we're exposed to it daily, says Dr. Jacob. And fetuses
and babies may not metabolize the chemical as well as adults, other experts
point out, so it's possible that it builds up in their small bodies.
Just Can These
The insides of food cans are often lined with an epoxy resin
that keeps corroding metal away from the food. But bisphenol A in that resin
can migrate into the foods; in fact, it's the major source of our exposure to
the chemical, says the government's National Toxicology Program. While the FDA
has issued reassuring statements about the risk, other experts aren't so
convinced. In 2007, the nonprofit Environmental Working Group found BPA in more
than half of the 97 food cans it tested, with the highest levels coming from
chicken soup, infant formula, and ravioli. Just one to three servings of those
foods with those concentrations could expose a woman or a child to BPA at
levels that cause serious adverse effects in animal tests, the group concluded.
Though you may see "BPA-free" on some canned
goods, food manufacturers are not required to list the chemical on labels, so
you have no way of knowing whether it's present. To limit your family's
exposure:
- ·
Buy more fresh or frozen fruits and vegetables.
- ·
Choose soups and broths that come in aseptic
boxes or dried soup mixes in nonplastic bags.
- ·
Be extra cautious with infants: If you use
commercial formula, buy it in powdered form, which comes in a foil-lined
cardboard container and shouldn't have any BPA, says the FDA.
- ·
Use BPA-free baby bottles and sippy cups.
Tiny Amounts, Big Problems
Despite BPA's pervasiveness in nearly all of us, the actual
amount found in our blood and urine is very small perhaps equivalent to mere
drops of water in a swimming pool. That's not enough to harm us, according to
the FDA, which first reviewed BPA in the 1980s, and in August issued a draft
report stating that exposure to the small amounts of BPA that migrate from
containers into the food they hold is not dangerous.
Traditionally, government toxicologists have operated under
the well-known theory that "the dose makes the poison" the more
chemical you ingest, the sicker you get. Keep the levels below a certain
threshold and you'll be OK. That's why the FDA issued its reassuring statement
and why the American Chemistry Council, an industry trade group, also believes
the amounts of BPA we ingest are safe. "An average adult would have to
consume more than 500 pounds of canned foods and beverages every day" just
to reach the safety standards set in the U.S. and Europe, says Steven Hentges,
executive director of the ACC's Polycarbonate/BPA Global Group.
But even if we're not being directly poisoned, there still
may be chronic health effects, say experts whose studies point to a different
way of assessing harm. BPA and phthalates are what are known as endocrine
disruptors chemicals that can interfere with our hormone systems, mimicking, shutting
down, or modifying the chemical signals that regulate everything from
metabolism and reproduction to our bodies' response to stress.
This new understanding turns the "dose makes the
poison" logic on its head, suggesting that even tiny levels can cause
damage if exposure happens at a particularly sensitive time during development,
such as when a fetus's brain or sex organs are forming in the womb. "There
are critical windows of vulnerability," says Maida Galvez, M.D., a
pediatrician with the Mount Sinai Pediatric Environmental Health Specialty Unit
in New York City. "It can be a question of when in addition to how
much." Or, as some scientists now put it, "the timing makes the
poison," says Andrea Gore, Ph.D., who studies hormone disruptors at the University
of Texas at Austin.
Until recently, researchers had no way to detect the small
amounts that are at the heart of this controversy. But "now that we can
measure these low levels, we see how incredibly potent these compounds
are," says David O. Norris, Ph.D., an endocrinologist at the University of
Colorado at Boulder. It's possible, say many researchers, that early exposure
to chemicals like BPA is making more of us grow up to be chubby, infertile, or
more prone to illness as kids and adults.
Messing with Our Hormones
It's no surprise that BPA affects hormones the molecule
was tested in the 1930s as an artificial estrogen. But it was passed over for a
stronger synthetic estrogen the notorious diethylstilbestrol (DES) which,
starting in the 1940s, was given to pregnant women to prevent miscarriage. Many
women used DES until the early 1970s, when researchers discovered it was
causing an unusual cancer of the reproductive tract in young women who'd been
exposed to the hormone in the womb. (Ironically, it turned out that DES didn't
prevent the miscarriages for which it had been prescribed in the first place.)
Today, as DES children and now DES grandchildren have grown up, doctors
have cataloged a long list of reproductive and other abnormalities linked to
the drug.
As for BPA, its dark side began to emerge in the 1990s. One
dramatic discovery happened by accident: In 1998, Patricia Hunt, Ph.D., a
reproductive biologist then at Case Western Reserve University, was studying
mouse eggs when her experiment suddenly went haywire. Her control mice the
healthy ones started developing the sorts of genetically abnormal eggs that
can lead to miscarriages and birth defects. "We checked everything,"
Hunt says. "Was it the air in the facility? Were there pesticides coming
in?" Finally, after weeks, they found that a temporary worker had used the
wrong detergent to clean the plastic cages and water bottles, causing BPA to
leach into the mice's water and environment.
While more and more reports about BPA-affected lab animals
were coming in, other scientists were growing concerned about another group of
endocrine disruptors: phthalates. They are added to many plastic products
automobile dashboards, vinyl shower curtains, raincoats, even your toddler's
rubber ducky to make them soft or pliable. Certain phthalates are also used
in beauty products, to prevent chipping in nail polish, for example.
Like BPA, phthalates have been "added" to most of
us as well. In a CDC study published in 2004, more than 75 percent of the 2,540
men, women, and children surveyed had measurable levels of seven different
phthalates in their urine, with children having the highest levels of three of
the chemicals. The numbers were startling and puzzling: "We don't really
know where all our exposure comes from," says Shanna Swan, Ph.D., director
of the Center for Reproductive Epidemiology at the University of Rochester in
Rochester, NY. "It's not like DES. We can't just ask if you've taken a
drug. This is a silent, hidden exposure." Swan and other experts believe,
though, that phthalates might come from household dust and food.
Are These Chemicals Making Us Sick?
With BPA and phthalates, there's nothing like the
smoking-lung cancer connection, but there are lots of smoking guns. The
research is still in its early days, and much of what we know comes from work
with animals. Also, not all phthalates have been linked to health problems. But
many prominent scientists believe these chemicals may cause a range of problems
related to our hormones:
Lower sperm counts and other reproductive abnormalities:
Since the late 1990s, after Hunt found that mice in BPA-contaminated cages
developed egg abnormalities, she and dozens of other researchers have linked
the chemical to reproductive problems in rodents, including lower sperm counts
and abnormal eggs. Phthalates, too, may cause reproductive problems. In 2006,
when Harvard researchers studied 463 men seeking treatment at a fertility
clinic, the scientists reported that men with higher levels of certain
phthalates in their urine had lower sperm counts and sperm motility, as well as
damage to sperm DNA, all of which affect the ability to impregnate a partner.
In one of the most important human studies so far, Swan
measured phthalates in 85 pregnant women in three U.S. cities Los Angeles,
Minneapolis, and Columbia, MO. In that 2005 study, women with the highest
phthalate levels were most likely to give birth to sons with smaller penises,
smaller testes, and "reduced ano-genital distance" (the space between
the testes and the anus). In other words, these baby boys were somewhat
de-masculinized, which could signal impaired semen quality and decreased
fertility later on. "The results were dramatic," Swan says. "We
were surprised by how strong the link was. And, based on animal studies, we're
concerned about possibly serious health consequences for these boys as they get
older."
Early puberty: "We think girls are maturing younger and
younger," says Mount Sinai's Dr. Galvez, "and we're now trying to
find out if endocrine disruptors play a role." Her center is involved in a
large study that is tracking 1,200 girls, currently ages 6 to 8, for five
years. But there are already clues. In Puerto Rico, researchers have been
studying girls who have developed breasts at extremely young ages (before 8,
and most starting before 2). Their 2000 study showed that these children had
phthalate levels, on average, almost seven times higher than those in a control
group of girls. While the researchers stress that this correlation does not
prove there's a link, their report concludes, ominously, that "if the
hypothesis holds true, premature sexual development in Puerto Rico may prove to
be an unfortunate example of the impact of endocrine-disrupting environmental
chemicals at a critical stage of human development."
Cancer: Early puberty, in turn, has been linked to an
increased risk of breast cancer. BPA, too, causes precancerous growths in lab
animals, both prostate and breast abnormalities. But in humans it's hard to
prove cause and effect with 100 percent certainty, says Andrea Gore.
"We're exposed to so many things, and our mothers ate and drank this or
that and 50 years later we get breast cancer," she says. "How can you
go back and say, 'It must be this chemical?'"
Obesity and diabetes: In one study of adult men, those with
higher-than-average phthalate levels tended to have a larger waist
circumference and increased insulin resistance, precursors to diabetes. In a
study of mice, the ones fed BPA were more likely to give birth to offspring who
became obese.
Neurobehavioral abnormalities: In a lengthy review article,
published in 2007, researchers reported that low doses of BPA during
development affect brain structure, function, and behavior in rats and mice.
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