L
Lisa
Guest
Chemical reaction
For years, athletes and hikers have toted their water in
colourful, durable BPA bottles. Baby bottles, too, have been
made of bisphenol A -- strong, shatterproof, easy to heat in the
microwave. Now, all of sudden, BPA is in headlines. Stores are
pulling BPA containers at the same time that new studies are
raising more concerns. Determined to separate facts from fears,
TOM SPEARS took a hard look at the science
Tom Spears
The Ottawa Citizen
Sunday, February 10, 2008
It has been a busy winter for bisphenol A, a component in some plastics that
kept a low profile for 60 years, until studies began suggesting it may be
harming people by leaking out of plastic containers. Harming babies and
fetuses especially.
The chemical, widely known as BPA, is common in the epoxy resin that lines
metal food and drink cans. It is also found in plastic food containers, some
brands of baby bottles, and the large reusable water bottles favoured by
athletes and hikers.
BPA is the main ingredient in polycarbonate, a tough, flexible plastic that
resists food odours and stains.
But it's under attack from many directions, following suggestions that it makes
lab rats prone to prostate and breast cancer, diabetes and obesity. Industries
that use polycarbonate -- and some government health agencies -- insist the
material is safe.
Bisphenol A is present in most of our bodies, having "migrated" from soup and
soft drink cans or water bottles. In tiny amounts, BPA acts like a female sex
hormone. In the first major study of the chemical in 2003-04, the U.S. Centers
for Disease Control and Prevention found it in 93 per cent of Americans. It's
not yet known whether the level is rising or falling.
It is found at the highest levels in children (including teenagers) and fetuses;
some animal studies suggest it can prevent organs from forming properly.
All at once:
- Health Canada is studying BPA as one of 200 chemicals "of interest to
Canadians" where there's some evidence of toxicity. It expects to report in May
on how much of the chemical leaches out of polycarbonate baby bottles and
infant formula cans.
- The U.S. National Toxicology Program is reviewing possible human health
effects of BPA exposure from polycarbonate containers. It's due to report this
summer.
- A U.S. congressional committee sent letters to baby formula manufacturers,
including Nestlé and Mead Johnson, asking if they use BPA in packaging and
test for it in infant food.
The committee is also asking if the Food and Drug Administration was wrong to
conclude the chemical is safe for such uses.
- After a parents' rally on Queen's Park, Premier Dalton McGuinty said Ontario
could become the first jurisdiction in Canada to place restrictions on bisphenol
A.
- Mountain Equipment Co-op removed polycarbonate plastic Nalgene bottles
from its stores last year. Lululemon did the same. Both companies said the
decision was a precautionary measure. MEC still sells Nalgene brand bottles
and food containers made of other plastics.
- Two weeks ago, a University of Cincinnati study found that running boiling
water into a polycarbonate container -- regardless of its age -- made BPA leach
out up to 55 times faster. Microwaving the plastic has a similar effect, said the
published study by scientist Scott Belcher.
- And on Thursday, an activist group called Environmental Defence reported on
lab tests it commissioned, which found that BPA leaches out of polycarbonate
baby bottles made by Gerber, Playtex and Avent.
This year, the world will use between
1.5 billion and 2.8 billion kilograms of BPA.
Now, prompted by a flurry of studies on rats, scientists are wondering: What if
it's dangerous?
In order to answer this question, they must first answer another: What's the
proper way to poison a rat? More precisely, how does feeding a rat industrial
chemicals for a few weeks accurately forecast the health effects on humans
who get much smaller doses spread over a lifetime?
LIFE BEFORE PLASTIC
The BPA story began 60 years ago, and its origins had nothing to do with
plastic.
In the 1940s, scientists trying to reduce the number of miscarriages wondered
if a synthetic estrogen drug would help women carry fetuses safely to term.
They settled on a chemical called diethylstilbestrol, better known today as
DES. It did unexpected but horrible damage; the women who took it were
mostly unharmed, but their children suffered health problems, particularly
reproductive tract cancers at a very young age in "DES daughters."
But while drug companies experimented with DES, they were also testing an
alternative called bisphenol A, or BPA for short. It was a chemical first
discovered in 1891 by a chemist who had no use for it at the time. Like DES, it
is a synthetic version of estrogen, the group of hormones that regulate most of
the female reproductive system. But it didn't perform as well in drug tests:
BPA didn't dissolve easily in water or stay in the body for long. Unlike DES, it
needed to be injected to work.
Bisphenol A was discarded as a drug for pregnant women, but in 1952 the
plastics industry found another use. It worked really, really well as a plastic.
In hardened form, it's called polycarbonate and forms a clear, durable plastic
(which can also be coloured). We see it every day in CDs, in automotive parts,
in the resin lining applied to the insides of food and soft drink cans, in toys.
For years, athletes and hikers have used colourful BPA bottles for water.
They're strong; they can hold boiling liquids; they don't crack in cold weather or
in hot dishwashers. Environmentalists like them, too: They're reusable for
many years.
Baby formula bottles are often (not always) made of BPA, too. The material
doesn't shatter, and parents find them easy to heat in the microwave.
The debate about BPA is much like disputes over other environmental
chemicals, from dioxin to manure from factory farms. Force-feed the stuff to
rats and they get sick. But what about humans in the real world? There's no
way to say.
When testing drugs, scientists give real drugs to one group and a placebo to
another. Afterward, they compare their health.
But they can't do this with pollutants, obviously, since they could poison
people. So instead they test rats. Today there are well more than 100 studies
on the effects of BPA on rats, all stemming from the fact that early research
found rats injected with the chemical were more prone to obesity, cancer and
insulin resistance.
Among existing studies, however, there is a nasty split, all based on how each
scientist chose to give BPA to the rats.
DELIVERING THE CHEMICAL
Last spring, a trade journal of the American Chemical Society, called Chemical
and Engineering News, surveyed the studies published to date. Its finding:
"There is growing concern that the chemical may cause similar adverse effects
in humans, particularly in babies and young children. But there are vast
discrepancies in the findings of government-funded and industry experiments
that have explored the health effects of BPA."
"Among government-funded experiments on lab animals and tissues, 153 found
adverse effects and 14 did not," wrote senior editor Bette Hileman. In contrast,
"the majority of those that reported no harm were funded by chemical
corporations."
The defects, in studies that found them, included a tendency to develop
diabetes and obesity, enlarged prostate, changes in the breast tissue that
suggest being prone to breast cancer, and a cluster of slight deformities in the
male reproductive tract that scientists call "feminization." These deformities
are seen to occur in animals exposed to so-called endocrine disruptors, or
environmental chemicals that mimic hormones such as estrogen and may upset
the normal development of reproductive systems.
Hileman's survey reported "a number of potential sources of bias behind these
inconsistent study outcomes, including the use of strains of rats that are
insensitive to estrogen and choosing batches of animal feed that vary widely in
their estrogenic activities."
In other words, Hileman charges that some experiments were designed to keep
the rats healthy to demonstrate that the chemical is harmless in small
amounts.
The U.S. National Institute of Environmental Health Sciences decided to sort
out the confusion. It is now reviewing and hopes by next summer or fall to
release public information on whether there's health danger, and if so, how
much.
Its early draft reveals only mild worry. There is "some concern" that exposure
to BPA in the womb causes neural and behavioural changes, but only "minimal"
or "negligible" concern about other possible health damage.
But already, the panel conducting the review is under attack from the anti-BPA
side made up of academic researchers such as Frederick vom Saal at the
University of Missouri-Columbia, and Scott Belcher (University of Cincinnati).
That's because it discarded many studies that indicated danger from the
chemical, but accepted most of the industry-sponsored studies that showed no
potential for harm.
They explained that the studies that found BPA harmful used the wrong
method to deliver the chemical to lab rats. (Industry studies generally fed BPA
to the rats by mouth.) Injecting the chemical into the rat's blood does not
mimic the type of exposure that people have. We don't inject BPA, noted the
panel of government reviewers, we swallow little bits of it as molecules detach
from the plastic in food and drink containers.
The "pathway" of exposure makes a difference. When we eat it, our
metabolism breaks down and excretes a lot of it. That doesn't happen as
readily if the chemical is shot directly into the bloodstream.
Last month, anti-BPA forces launched a counter-attack. They published a new
study in a science journal called Reproductive Toxicity, showing that rat
fetuses and babies process the chemical in a different way than adult rats do.
The University of Missouri study gave high and low doses of BPA to
three-day-old female mice. Half got the chemical by mouth and half by
injection. Afterward, the mice with injections had the same blood levels as the
mice with oral doses.
"It shows that for the baby animals, it doesn't matter whether they get the
dose orally or they get the dose through the blood," Hileman explains. "They
can't really metabolize it the way adults can. So they seemed to be harmed
(equally) by injection and by oral exposures."
The implication: "If you're pregnant, then it might be much more harmful to
your baby and might not even bother you. The liver (in the fetus and baby)
doesn't break it down. If you're in the womb, you're not eating and your
system is different. Even in the first year (after birth), your system is not the
same as an adult's. So if you're getting it in your formula or your breast milk, it
might be more harmful to you than it would be to your mother or father.
"The only thing you can look at is that exposures to the animals at extremely
low levels now seem to cause harm, to those animals.
"We can't do those experiments on us, but we do know, (or) have a good idea,
how much babies are exposed to in the womb. And that's as much as the
animals that get harmed" in the lab.
The National Toxicology Program's panel released a letter after this news
became public, promising to consider all views about different methods of
exposure in making its decision.
'REASON TO BE CAUTIOUS'
Its multiyear review has many complex, bureaucratic steps. Here, for instance,
is the procedure just for one step, the final release of the "monograph," or
summary of how safe or dangerous the chemical is:
"The NTP Monograph will likely be available in summer 2008. This will allow
time for the brief to be drafted taking into account new literature and public
comments on the panel report, released for public comment, peer reviewed,
revised taking into account public and peer review comments on the draft NTP
Brief, and reviewed through NIEHS/NTP. The draft will be released for public
comment before this meeting."
"There is quite a bit of controversy going on," says Belcher, of the University of
Cincinnati.
His own work was part of the research discarded by the federal review panel --
because it was done in test tubes, or "in vitro," and not in live animals.
"The real consensus is there's clear reason to be cautious" about the chemical,
he says. "Now we don't know the magnitude of the effects in humans, but
there's clear reason to believe that it could (be) very wide-ranging, given the
scientific studies we have done and in wildlife."
Observations in the wild show that trout exposed to BPA started reproducing at
the wrong time; as well, lobsters from areas where the sea bed is tainted with
industrial and urban runoff showed physical defects. Neither of these gives
proof of cause-and-effect, though the Woods Hole Marine Biological Laboratory
says lobsters are especially prone to damage by hormone-like chemicals.
But industries that rely on BPA insist the material is safe. They point to the
early view of the review panel as evidence, but also to recent decisions (both
in 2006) by Japan and the European Food Safety Authority that BPA is safe
enough for use in food packaging.
'DON'T FIX IT IF IT'S NOT BROKEN'
When MEC pulled polycarbamate water bottles and food containers, Nalgene
responded that it, like government agencies, still feels the material is safe. It
adds, "several scientific panels including the European Union's Scientific
Committee on Food, the National Toxicology Program and the Harvard Center
for Risk Analysis have concluded that the weight of scientific evidence does not
support the hypothesis that low doses of BPA adversely affects human health.
None of the large studies conducted has substantiated the claims made by
those performing some of the smaller studies frequently cited."
"They (BPA-based plastics) have been used in the industry for over 60 years,"
said Gail Wood, spokeswoman for Mead Johnson Nutritionals, a division of
Bristol-Myers Squibb Company, a baby formula manufacturer. "They're very
important because they are the absolute best in keeping product fresh and
keeping contaminants out of whatever food product is canned ... using those
liners.
"It has been proven time and time again by leading government testing
authorities to be safe. So it's sort of like: Don't fix it if it's not broken.
"It is a very important resin for the industry. If there were something better...
"We trust that industry and all the governments of Japan, Europe and the U.S.
to be on the lookout for enhancements and betterment. But to date there
hasn't been any," she said.
"There are substitutes (other epoxies), but know this, too: Every alternative
has its inherent risks and benefits. So because the risks are so low in epoxy
resins, and their efficacy is so high, they are by far the best possible packaging
component to use for a myriad of applications."
Why not use unlined metal?
"Oh, my gosh! There is a significant leaching problem with those metals and
alloys," Wood said. Traces of nickel, aluminum or other toxic metals could
leach out of the can, contaminating the food.
Resin linings also seal out bacteria, moisture and oxygen (which spoil food).
"I wish people who were scaring consumers would present more of a balanced
story."
The BPA-based resins are also flexible, so the lining stays intact if something
dents the can.
"The key take-away (message) is that there probably are alternatives -- not as
good -- and every alternative is going to have its inherent risks and benefits."
The North American Metal Packaging Alliance, representing steel and aluminum
can makers, says BPA-based epoxy is "unsurpassed" in staying intact through
the high sterilizing temperatures used in food canning.
"This sterilization process guarantees that the packed food is safe from
microbiological contamination ('food poisoning') making the canned food the
safest for consumers," it says in a statement on BPA.
In the meantime, testing a chemical that gives off only a weak hormonal signal
is not simple.
"It's very difficult because these sorts of compounds don't work like your
normal toxins," the University of Cincinnati's Belcher says. "Part of the
difficulty is that when you talk about hormone systems, they're very sensitive
to very small changes. And often what happens -- and BPA is a good case -- is
that it's lower doses that have the bigger effects, which is very different for
toxicology and risk assessment the way we do it."
The body's hormone receptors ignore a big dose, because hormones don't
arrive in big doses. But if they see a small dose, they say: That's a hormonal
signal.
In the continuing battle over public opinion, it's easy to be fooled. The Toronto
Star was duped last month: It published a 10-part article listing various health
scares that it said were "unfounded."
The Star was actually reprinting material written by the American Council on
Science and Health. This group is paid by the U.S. chemical industry and
advances its views aggressively .
Its article, reprinted as health news in the Star, told readers: "The Bottom
Line: The United States Environmental Protection Agency concluded BPA is safe
and set a maximum acceptable dose of 0.05 milligrams per kilogram of body
weight. Only workers exposed to BPA on the job have shown any significant
effects, experiencing irritation of the eyes, respiratory tract and skin. These
symptoms resulted from inhaling BPA, not from ingesting it through foods and
beverages."
That's true as far as it goes, though it doesn't mention the continuing reviews.
On the other side, 38 BPA researchers -- not industry reps -- who gathered in
North Carolina for a workshop last August drew up a list of known, suspected
and uncertain aspects of the chemical, known now as the "Chapel Hill
Consensus Statement." It says the following statements are "likely, but require
confirmation:
" ... Exposure during sensitive periods in organogenesis (that is, when organs
are forming in the fetus) may increase susceptibility to development of cancers
in some organs, such as the prostate and mammary glands.
"Early life exposure to environmentally relevant BPA doses may result in
persistent adverse effects in humans.
"The function of the immune system can be altered following adult exposure to
BPA."
And the exact effect on humans in the real world? They put that down as
uncertain:
"There is a need for epidemiological studies relating health outcomes to BPA
exposure particularly during sensitive periods in development," they concluded.
- - -
How to Reduce Exposure to BPA
- Don't microwave polycarbonate plastic food containers. BPA is strong and
durable, but over time it may break down from overuse at high temperatures.
- Avoid plastic containers with the number "7" on the bottom.
- Don't wash polycarbonate plastic containers in the dishwasher with harsh
detergents.
- Reduce your use of canned foods. Eat fresh or frozen foods.
- When possible, opt for glass, porcelain or stainless steel containers,
particularly for hot food or liquids.
- Consider alternatives to products that contain BPA, such as PETE
(polyethylene terephthalate, ID code #1).
- Use infant formula bottles that are BPA-free and look for toys that are
labeled BPA-free.
- The highest potential for human exposure to bisphenol A is through products
that directly contact food, such as food and beverage containers with internal
epoxy resin coatings, and through the use of polycarbonate tableware and
bottles, such as those used to feed infants.
Source: U.S. National Institute of Environmental Health Sciences, National
Institutes of Health
For years, athletes and hikers have toted their water in
colourful, durable BPA bottles. Baby bottles, too, have been
made of bisphenol A -- strong, shatterproof, easy to heat in the
microwave. Now, all of sudden, BPA is in headlines. Stores are
pulling BPA containers at the same time that new studies are
raising more concerns. Determined to separate facts from fears,
TOM SPEARS took a hard look at the science
Tom Spears
The Ottawa Citizen
Sunday, February 10, 2008
It has been a busy winter for bisphenol A, a component in some plastics that
kept a low profile for 60 years, until studies began suggesting it may be
harming people by leaking out of plastic containers. Harming babies and
fetuses especially.
The chemical, widely known as BPA, is common in the epoxy resin that lines
metal food and drink cans. It is also found in plastic food containers, some
brands of baby bottles, and the large reusable water bottles favoured by
athletes and hikers.
BPA is the main ingredient in polycarbonate, a tough, flexible plastic that
resists food odours and stains.
But it's under attack from many directions, following suggestions that it makes
lab rats prone to prostate and breast cancer, diabetes and obesity. Industries
that use polycarbonate -- and some government health agencies -- insist the
material is safe.
Bisphenol A is present in most of our bodies, having "migrated" from soup and
soft drink cans or water bottles. In tiny amounts, BPA acts like a female sex
hormone. In the first major study of the chemical in 2003-04, the U.S. Centers
for Disease Control and Prevention found it in 93 per cent of Americans. It's
not yet known whether the level is rising or falling.
It is found at the highest levels in children (including teenagers) and fetuses;
some animal studies suggest it can prevent organs from forming properly.
All at once:
- Health Canada is studying BPA as one of 200 chemicals "of interest to
Canadians" where there's some evidence of toxicity. It expects to report in May
on how much of the chemical leaches out of polycarbonate baby bottles and
infant formula cans.
- The U.S. National Toxicology Program is reviewing possible human health
effects of BPA exposure from polycarbonate containers. It's due to report this
summer.
- A U.S. congressional committee sent letters to baby formula manufacturers,
including Nestlé and Mead Johnson, asking if they use BPA in packaging and
test for it in infant food.
The committee is also asking if the Food and Drug Administration was wrong to
conclude the chemical is safe for such uses.
- After a parents' rally on Queen's Park, Premier Dalton McGuinty said Ontario
could become the first jurisdiction in Canada to place restrictions on bisphenol
A.
- Mountain Equipment Co-op removed polycarbonate plastic Nalgene bottles
from its stores last year. Lululemon did the same. Both companies said the
decision was a precautionary measure. MEC still sells Nalgene brand bottles
and food containers made of other plastics.
- Two weeks ago, a University of Cincinnati study found that running boiling
water into a polycarbonate container -- regardless of its age -- made BPA leach
out up to 55 times faster. Microwaving the plastic has a similar effect, said the
published study by scientist Scott Belcher.
- And on Thursday, an activist group called Environmental Defence reported on
lab tests it commissioned, which found that BPA leaches out of polycarbonate
baby bottles made by Gerber, Playtex and Avent.
This year, the world will use between
1.5 billion and 2.8 billion kilograms of BPA.
Now, prompted by a flurry of studies on rats, scientists are wondering: What if
it's dangerous?
In order to answer this question, they must first answer another: What's the
proper way to poison a rat? More precisely, how does feeding a rat industrial
chemicals for a few weeks accurately forecast the health effects on humans
who get much smaller doses spread over a lifetime?
LIFE BEFORE PLASTIC
The BPA story began 60 years ago, and its origins had nothing to do with
plastic.
In the 1940s, scientists trying to reduce the number of miscarriages wondered
if a synthetic estrogen drug would help women carry fetuses safely to term.
They settled on a chemical called diethylstilbestrol, better known today as
DES. It did unexpected but horrible damage; the women who took it were
mostly unharmed, but their children suffered health problems, particularly
reproductive tract cancers at a very young age in "DES daughters."
But while drug companies experimented with DES, they were also testing an
alternative called bisphenol A, or BPA for short. It was a chemical first
discovered in 1891 by a chemist who had no use for it at the time. Like DES, it
is a synthetic version of estrogen, the group of hormones that regulate most of
the female reproductive system. But it didn't perform as well in drug tests:
BPA didn't dissolve easily in water or stay in the body for long. Unlike DES, it
needed to be injected to work.
Bisphenol A was discarded as a drug for pregnant women, but in 1952 the
plastics industry found another use. It worked really, really well as a plastic.
In hardened form, it's called polycarbonate and forms a clear, durable plastic
(which can also be coloured). We see it every day in CDs, in automotive parts,
in the resin lining applied to the insides of food and soft drink cans, in toys.
For years, athletes and hikers have used colourful BPA bottles for water.
They're strong; they can hold boiling liquids; they don't crack in cold weather or
in hot dishwashers. Environmentalists like them, too: They're reusable for
many years.
Baby formula bottles are often (not always) made of BPA, too. The material
doesn't shatter, and parents find them easy to heat in the microwave.
The debate about BPA is much like disputes over other environmental
chemicals, from dioxin to manure from factory farms. Force-feed the stuff to
rats and they get sick. But what about humans in the real world? There's no
way to say.
When testing drugs, scientists give real drugs to one group and a placebo to
another. Afterward, they compare their health.
But they can't do this with pollutants, obviously, since they could poison
people. So instead they test rats. Today there are well more than 100 studies
on the effects of BPA on rats, all stemming from the fact that early research
found rats injected with the chemical were more prone to obesity, cancer and
insulin resistance.
Among existing studies, however, there is a nasty split, all based on how each
scientist chose to give BPA to the rats.
DELIVERING THE CHEMICAL
Last spring, a trade journal of the American Chemical Society, called Chemical
and Engineering News, surveyed the studies published to date. Its finding:
"There is growing concern that the chemical may cause similar adverse effects
in humans, particularly in babies and young children. But there are vast
discrepancies in the findings of government-funded and industry experiments
that have explored the health effects of BPA."
"Among government-funded experiments on lab animals and tissues, 153 found
adverse effects and 14 did not," wrote senior editor Bette Hileman. In contrast,
"the majority of those that reported no harm were funded by chemical
corporations."
The defects, in studies that found them, included a tendency to develop
diabetes and obesity, enlarged prostate, changes in the breast tissue that
suggest being prone to breast cancer, and a cluster of slight deformities in the
male reproductive tract that scientists call "feminization." These deformities
are seen to occur in animals exposed to so-called endocrine disruptors, or
environmental chemicals that mimic hormones such as estrogen and may upset
the normal development of reproductive systems.
Hileman's survey reported "a number of potential sources of bias behind these
inconsistent study outcomes, including the use of strains of rats that are
insensitive to estrogen and choosing batches of animal feed that vary widely in
their estrogenic activities."
In other words, Hileman charges that some experiments were designed to keep
the rats healthy to demonstrate that the chemical is harmless in small
amounts.
The U.S. National Institute of Environmental Health Sciences decided to sort
out the confusion. It is now reviewing and hopes by next summer or fall to
release public information on whether there's health danger, and if so, how
much.
Its early draft reveals only mild worry. There is "some concern" that exposure
to BPA in the womb causes neural and behavioural changes, but only "minimal"
or "negligible" concern about other possible health damage.
But already, the panel conducting the review is under attack from the anti-BPA
side made up of academic researchers such as Frederick vom Saal at the
University of Missouri-Columbia, and Scott Belcher (University of Cincinnati).
That's because it discarded many studies that indicated danger from the
chemical, but accepted most of the industry-sponsored studies that showed no
potential for harm.
They explained that the studies that found BPA harmful used the wrong
method to deliver the chemical to lab rats. (Industry studies generally fed BPA
to the rats by mouth.) Injecting the chemical into the rat's blood does not
mimic the type of exposure that people have. We don't inject BPA, noted the
panel of government reviewers, we swallow little bits of it as molecules detach
from the plastic in food and drink containers.
The "pathway" of exposure makes a difference. When we eat it, our
metabolism breaks down and excretes a lot of it. That doesn't happen as
readily if the chemical is shot directly into the bloodstream.
Last month, anti-BPA forces launched a counter-attack. They published a new
study in a science journal called Reproductive Toxicity, showing that rat
fetuses and babies process the chemical in a different way than adult rats do.
The University of Missouri study gave high and low doses of BPA to
three-day-old female mice. Half got the chemical by mouth and half by
injection. Afterward, the mice with injections had the same blood levels as the
mice with oral doses.
"It shows that for the baby animals, it doesn't matter whether they get the
dose orally or they get the dose through the blood," Hileman explains. "They
can't really metabolize it the way adults can. So they seemed to be harmed
(equally) by injection and by oral exposures."
The implication: "If you're pregnant, then it might be much more harmful to
your baby and might not even bother you. The liver (in the fetus and baby)
doesn't break it down. If you're in the womb, you're not eating and your
system is different. Even in the first year (after birth), your system is not the
same as an adult's. So if you're getting it in your formula or your breast milk, it
might be more harmful to you than it would be to your mother or father.
"The only thing you can look at is that exposures to the animals at extremely
low levels now seem to cause harm, to those animals.
"We can't do those experiments on us, but we do know, (or) have a good idea,
how much babies are exposed to in the womb. And that's as much as the
animals that get harmed" in the lab.
The National Toxicology Program's panel released a letter after this news
became public, promising to consider all views about different methods of
exposure in making its decision.
'REASON TO BE CAUTIOUS'
Its multiyear review has many complex, bureaucratic steps. Here, for instance,
is the procedure just for one step, the final release of the "monograph," or
summary of how safe or dangerous the chemical is:
"The NTP Monograph will likely be available in summer 2008. This will allow
time for the brief to be drafted taking into account new literature and public
comments on the panel report, released for public comment, peer reviewed,
revised taking into account public and peer review comments on the draft NTP
Brief, and reviewed through NIEHS/NTP. The draft will be released for public
comment before this meeting."
"There is quite a bit of controversy going on," says Belcher, of the University of
Cincinnati.
His own work was part of the research discarded by the federal review panel --
because it was done in test tubes, or "in vitro," and not in live animals.
"The real consensus is there's clear reason to be cautious" about the chemical,
he says. "Now we don't know the magnitude of the effects in humans, but
there's clear reason to believe that it could (be) very wide-ranging, given the
scientific studies we have done and in wildlife."
Observations in the wild show that trout exposed to BPA started reproducing at
the wrong time; as well, lobsters from areas where the sea bed is tainted with
industrial and urban runoff showed physical defects. Neither of these gives
proof of cause-and-effect, though the Woods Hole Marine Biological Laboratory
says lobsters are especially prone to damage by hormone-like chemicals.
But industries that rely on BPA insist the material is safe. They point to the
early view of the review panel as evidence, but also to recent decisions (both
in 2006) by Japan and the European Food Safety Authority that BPA is safe
enough for use in food packaging.
'DON'T FIX IT IF IT'S NOT BROKEN'
When MEC pulled polycarbamate water bottles and food containers, Nalgene
responded that it, like government agencies, still feels the material is safe. It
adds, "several scientific panels including the European Union's Scientific
Committee on Food, the National Toxicology Program and the Harvard Center
for Risk Analysis have concluded that the weight of scientific evidence does not
support the hypothesis that low doses of BPA adversely affects human health.
None of the large studies conducted has substantiated the claims made by
those performing some of the smaller studies frequently cited."
"They (BPA-based plastics) have been used in the industry for over 60 years,"
said Gail Wood, spokeswoman for Mead Johnson Nutritionals, a division of
Bristol-Myers Squibb Company, a baby formula manufacturer. "They're very
important because they are the absolute best in keeping product fresh and
keeping contaminants out of whatever food product is canned ... using those
liners.
"It has been proven time and time again by leading government testing
authorities to be safe. So it's sort of like: Don't fix it if it's not broken.
"It is a very important resin for the industry. If there were something better...
"We trust that industry and all the governments of Japan, Europe and the U.S.
to be on the lookout for enhancements and betterment. But to date there
hasn't been any," she said.
"There are substitutes (other epoxies), but know this, too: Every alternative
has its inherent risks and benefits. So because the risks are so low in epoxy
resins, and their efficacy is so high, they are by far the best possible packaging
component to use for a myriad of applications."
Why not use unlined metal?
"Oh, my gosh! There is a significant leaching problem with those metals and
alloys," Wood said. Traces of nickel, aluminum or other toxic metals could
leach out of the can, contaminating the food.
Resin linings also seal out bacteria, moisture and oxygen (which spoil food).
"I wish people who were scaring consumers would present more of a balanced
story."
The BPA-based resins are also flexible, so the lining stays intact if something
dents the can.
"The key take-away (message) is that there probably are alternatives -- not as
good -- and every alternative is going to have its inherent risks and benefits."
The North American Metal Packaging Alliance, representing steel and aluminum
can makers, says BPA-based epoxy is "unsurpassed" in staying intact through
the high sterilizing temperatures used in food canning.
"This sterilization process guarantees that the packed food is safe from
microbiological contamination ('food poisoning') making the canned food the
safest for consumers," it says in a statement on BPA.
In the meantime, testing a chemical that gives off only a weak hormonal signal
is not simple.
"It's very difficult because these sorts of compounds don't work like your
normal toxins," the University of Cincinnati's Belcher says. "Part of the
difficulty is that when you talk about hormone systems, they're very sensitive
to very small changes. And often what happens -- and BPA is a good case -- is
that it's lower doses that have the bigger effects, which is very different for
toxicology and risk assessment the way we do it."
The body's hormone receptors ignore a big dose, because hormones don't
arrive in big doses. But if they see a small dose, they say: That's a hormonal
signal.
In the continuing battle over public opinion, it's easy to be fooled. The Toronto
Star was duped last month: It published a 10-part article listing various health
scares that it said were "unfounded."
The Star was actually reprinting material written by the American Council on
Science and Health. This group is paid by the U.S. chemical industry and
advances its views aggressively .
Its article, reprinted as health news in the Star, told readers: "The Bottom
Line: The United States Environmental Protection Agency concluded BPA is safe
and set a maximum acceptable dose of 0.05 milligrams per kilogram of body
weight. Only workers exposed to BPA on the job have shown any significant
effects, experiencing irritation of the eyes, respiratory tract and skin. These
symptoms resulted from inhaling BPA, not from ingesting it through foods and
beverages."
That's true as far as it goes, though it doesn't mention the continuing reviews.
On the other side, 38 BPA researchers -- not industry reps -- who gathered in
North Carolina for a workshop last August drew up a list of known, suspected
and uncertain aspects of the chemical, known now as the "Chapel Hill
Consensus Statement." It says the following statements are "likely, but require
confirmation:
" ... Exposure during sensitive periods in organogenesis (that is, when organs
are forming in the fetus) may increase susceptibility to development of cancers
in some organs, such as the prostate and mammary glands.
"Early life exposure to environmentally relevant BPA doses may result in
persistent adverse effects in humans.
"The function of the immune system can be altered following adult exposure to
BPA."
And the exact effect on humans in the real world? They put that down as
uncertain:
"There is a need for epidemiological studies relating health outcomes to BPA
exposure particularly during sensitive periods in development," they concluded.
- - -
How to Reduce Exposure to BPA
- Don't microwave polycarbonate plastic food containers. BPA is strong and
durable, but over time it may break down from overuse at high temperatures.
- Avoid plastic containers with the number "7" on the bottom.
- Don't wash polycarbonate plastic containers in the dishwasher with harsh
detergents.
- Reduce your use of canned foods. Eat fresh or frozen foods.
- When possible, opt for glass, porcelain or stainless steel containers,
particularly for hot food or liquids.
- Consider alternatives to products that contain BPA, such as PETE
(polyethylene terephthalate, ID code #1).
- Use infant formula bottles that are BPA-free and look for toys that are
labeled BPA-free.
- The highest potential for human exposure to bisphenol A is through products
that directly contact food, such as food and beverage containers with internal
epoxy resin coatings, and through the use of polycarbonate tableware and
bottles, such as those used to feed infants.
Source: U.S. National Institute of Environmental Health Sciences, National
Institutes of Health
