Note: 5-gallon polycarbonate water bottles contain 'bisphenol A'.
_____________________________________________________________________
See also:
Raloff, J. 1997. Dental sealant safety reconsidered. Science News 152
(Nov. 22):324. http://www.sciencenews.org/sn_arc97/11_22_97/fob1.htm
_____________________________________________________________________
Note: Many types of white composite (plastic) fillings are leaking
synthetic- estrogen into the saliva, around the clock. A few
dental composites said to NOT contain 'bisphenol A' are:
1) Procera
2) Diamond Lite and Diamond Crown
3) Targis Vectris --
Fiber- reinforced poly-ceramic crowns and bridges:
http://www.dentalceramicsinc.com/Dental_Ceramics_Targis_Vectris.htm
4) Sculpture FibreKor --
Fiber- reinforced poly-ceramic crowns and bridges:
http://www.killiandental.com/sculptur.htm
_____________________________________________________________________
Two articles follow :
BISPHENOL A CONTRIBUTES TO WEIGHT GAIN, EARLY PUBERTY
WHAT'S COMING OUT OF BABY'S BOTTLE ?
_____________________________________________________________________
http://www.tmc.tulane.edu/ecme/eehome/newsviews/research/bpa2_00.html
BISPHENOL A CONTRIBUTES TO WEIGHT GAIN, EARLY PUBERTY
Posted February 22, 2000
Review by Kembra L. Howdeshell
Research paper:
EXPOSURE TO BISPHENOL A ADVANCES PUBERTY.
Howdeshell, Kembra L., Andrew K. Hotchkiss, Kristina A.
Thayer, John G. Vandenbergh, and Frederick S. vom Saal.
NATURE, 401(Oct 21, 1999):763-764.
Article summary by Kembra L. Howdeshell,
University of Missouri, Columbia.
Over the past decades, researchers have reported a
dramatic increase in the number of overweight Americans
and a decrease in the age at which young girls reach
puberty. These findings have been attributed to
nutrition, lifestyle, and genetics. However, a team of
researchers at the University of Missouri-Columbia and
North Carolina State University reported in the October
21, 1999, issue of Nature that an estrogen-mimicking
chemical used in the manufacture of certain plastic
products could be a contributing factor.
Kembra Howdeshell, a University of Missouri doctoral
candidate, and Frederick vom Saal, biology professor at
the University of Missouri, exposed mice to a level of
bisphenol A comparable to human exposure. Bisphenol A,
an estrogen-mimicking chemical, is a building block for
the production of polycarbonate plastic products, such
as baby bottles, the resin lining of food cans, and
certain types of food storage containers. Bisphenol A
exposure occurs because the chemical is known to leach
from such products.
Pregnant mice were fed a low level of bisphenol A (2.4
micrograms per kilogram or 2.4 parts per billion)during
days 11-17 of their 19-day pregnancy, thus exposing the
developing pups in the womb. Female mice born to
bisphenol A-treated mothers had an earlier onset of
puberty and were up to 20% heavier than those born to
oil-fed control mothers. However, the female offspring
with highest levels of natural estrogen were much more
sensitive to the chemical and showed the largest weight
gain and earliest puberty relative to those females with
low levels of natural estrogen.
Specifically, the bisphenol A-exposed females with
highest natural estrogen levels reached puberty 5 days
earlier and were 20% heavier at weaning (22-days -old)
than their untreated counterparts. (while) Female
offspring with the lowest levels of natural estrogen did
not show a difference from controls based on their
exposure to bisphenol A.
Such variation in natural estrogen levels also exists in
the human population and could be influencing the
sensitivity of humans to such chemicals during sensitive
periods of development in the womb. It is difficult to
assess the levels of estrogen-mimicking chemicals to
which humans are exposed and their impact on
reproductive physiology. However, it is interesting to
note that an increase in the number of hormone-sensitive
reproductive abnormalities has occurred concurrent with
the widespread use of hormone-disruptive agents in the
environment, thus suggesting an association.
These research findings do not directly answer questions
concerning effects in humans; instead the findings pose
a question regarding human health and may serve as a
guide for human research. The researchers state that
bisphenol A should be considered as a factor
contributing to the changes in growth, sexual
maturation, and reproductive abnormalities that have
been reported in the humans in the past decades.
References/Further reading:
1. Nagel, S.C., F.S. vom Saal, K.A. Thayer, M.G. Dhar,
M. Boechler, and W.V. Welshons. 1997. Relative
binding affinity-serum modified access (RBA-SMA)
assay predicts the relative in vivo bioactivity of
the xenoestrogens bisphenol A and octylphenol.
Environmental Health Perspectives, 105:70-76.
2. Ben-Jonathan, N. and R. Steinmetz. 1998.
Xenoestrogens: the emerging story of bisphenol A.
Trends in Endocrinology and Metabolism, 9:124-128.
3. vom Saal, F.S., P.S. Cooke, D.L. Buchanan, P.
Palanza, K.A. Thayer, S.C. Nagel, S. Parmigiani, and
W.V. Welshons. 1998. A physiologically based
approach to the study of bisphenol A and other
estrogenic chemicals on the size of reproductive
organs daily sperm production and behavior.
Toxicology and Industrial Health, 14:239-260.
4. Takao, Y., H.C. Lee, Y. Ishibashi, S. Kohra, N.
Tominaga, and K. Arizono. 1999. Fast screening
method for bisphenol A in environmental water and in
food by solid-phase microextraction (SPME). Journal
of Health Science, 45:39.
Last page update: Wednesday, February 23, 2000
Copyright (c) 1996-2000 Center for Bioenvironmental Research
at Tulane and Xavier Universities
_____________________________________________________________________
http://www.sciencenews.org/sn_arc99/7_24_99/food.htm
SCIENCE NEWS ONLINE
The Weekly Newsmagazine of Science
July 24, 1999 Vol. 156, No. 4
WHAT'S COMING OUT OF BABY'S BOTTLE ?
Parents become rightly upset when they read news accounts of
federal inspectors finding insect bits, pesticides, and other
contaminants lacing foods that their children will eat. A new
Japanese study now suggests that the plastic tableware and
containers from which we often serve foods may contribute
adulterants of their own -- hormone-mimicking building blocks
of a plastic.
Roughly 95 percent of all baby bottles currently on the market are
made of polycarbonate. As the poly in polycarbonate implies, this
plastic is a polymer -- a chainlike molecule constructed by linking
up individual units of a common chemical. In this case, each link
is a molecule of bisphenol A.
Toxicologist Koji Arizono of the Prefectural University of
Kumamoto, Japan, and his colleagues tested 10 different brands of
polycarbonate baby bottles -- purchased in the United States,
Germany, Japan, Korea, Malaysia, and the Philippines -- along with
other types of clear-plastic tableware. When heated, all leached
bisphenol A, a chemical that mimics the hormone estrogen, into the
liquids they held.
Pollutants that emulate hormones -- especially estrogen -- have
emerged in recent years as a major environmental concern. Animal
studies suggest they might increase an individual's likelihood of
developing certain cancers. During development, exposure to these
environmental hormones also risks disrupting the normal growth and
function of reproductive tissues and the brain. Although roughly a
dozen animal or cellular studies on bisphenol A show a variety of
biological effects, whether these changes have implications for
people's health remains controversial.
Last year, the Environmental Protection Agency launched a new
program to begin identifying and studying such hormone-mimicking
pollutants (SN: 10/17/98, p. 251).
Some of the data by Arizono's team, which are due to be formally
published in Japanese later this year, were unveiled at a press
briefing in May by Thomas Natan, research director of the
Washington D.C.-based National Environmental Trust. The event
marked the submission of a petition to the Food and Drug
Administration (FDA) asking that polycarbonate baby bottles and
foodware be labeled so that concerned consumers could avoid using
them.
This clear rigid plastic is a mainstay of baby bottles, picnic
cutlery, unbreakable kitchen tumblers used to serve up milk and
other drinks, the carboys that hold bottled water, even the
cafeteria bowls used for soups.
Bisphenol A draws attention to itself
As early as 1936, British chemists reported finding that bisphenol
A functions like a weak estrogen. Because only traces of unlinked
bisphenol A were present in plastics, and because the material's
early uses were not for food containers, the result was largely
forgotten.
Until June 1993. That's when some experiments being conducted by
Aruna V. Krishnan and David Feldman of the Stanford University
School of Medicine went awry.
The pair had been looking for signs that yeast might produce
estrogenlike compounds. But every time the researchers sterilized a
batch of growth medium to feed their yeast, the flasks holding the
medium added something that resembled estrogen. As it turns out,
the flasks were polycarbonate, and they were leaching bisphenol A.
Though the manufacturer knew its flasks could leach traces of
bisphenol A upon heating, it had considered the amounts
inconsequential. They were usually at or below the general limit of
detection at that time -- about 10 parts per billion. In the
Stanford tests, however, bisphenol-A migration of just 2 to 5 parts
per billion thoroughly derailed the yeast experiments (SN: 7/3/93,
p. 12).
Since then, a number of labs around the world have been probing to
see what else leaches bisphenol A. And the more scientists look,
the more they find.
For instance, 4 years ago, the plastic resins used to line roughly
half of the food cans in Europe and 85 percent of U.S. food cans
proved to be a source of dietary bisphenol A.
Nicolás Olea and his colleagues at the University of Granada
analyzed the contents of 20 different brands of canned foods
purchased at various groceries in Europe and the United States.
They included a range of popular items: corn, tomatoes, mushrooms,
even artichoke hearts. Measurable quantities of bisphenol A turned
up in roughly half of all foods sampled (SN: 6/3/95, p. 341).
What's troubling, Olea noted, is that consumers have no way of
knowing whether their canned goods have been packed in a
plastic-lined container. That information was not provided on the
label.
One year later, Olea's team reported finding that bisphenol A
leaches from some of the plastic resins commonly used to seal tooth
surfaces. While these sealants reduce the risk that treated teeth
will develop cavities, the Spanish researchers pointed out that
newly applied sealants leave measurable quantities of bisphenol A
in the mouth. It turned up in samples of saliva collected an hour
after treatment -- and in one case, 2 years later (SN: 4/6/96, p.
214).
Food and Drug Administration chemists were next to weigh in on
bisphenol A. Two years ago, they reported that some unbound
bisphenol A leached from polycarbonate baby bottles and juice cups
that had been heated. There findings also suggested that some of
the heating had actually started degrading the plastic -- freeing
up additional bisphenol A for leaching, said John E. Biles, one of
the study's authors (SN: 10/18/97, p. 255).
However, the FDA data indicated that the amount of bisphenol A that
leached into a fatty material -- designed to simulate infant
formula -- was quite small. Now, Arizono's group has employed a
sensitive new analytical technique to assay for the hormone mimic.
Their data indicate that through normal use, polycarbonates leach
more bisphenol A than reports by others had indicated. The
concentrations of bisphenol A that result are in the same range as
those that caused abnormalities in rats.
Well-used polycarbonates leach the most
Most earlier studies investigated bisphenol-A leaching by new
laboratory ware, new dental sealants, or new bottles. To probe
how wear and tear might affect the migration of this chemical,
Arizono's team compared rates of bisphenol A release from shiny
new baby bottles and from bottles that were hazy and crackled,
reflecting years of use.
Because heating, such as the boiling used to sterilize bottles,
facilitates bisphenol-A release, Arizono put 90 °C water in contact
with the polycarbonate materials for 30 minutes and then measured
how much bisphenol A ended up in the water.
For new baby bottles, the water picked up between 1 and 3.5 parts
per billion (ppb) bisphenol A. Water heated in used but relatively
clear bottles sometimes picked up as much as 6.5 ppb. Water in very
worn and heavily scratched bottles acquired between 10 and 28 ppb
of the compound.
Coming from a culture that esteems its soup, Arizono then filled
polycarbonate soup bowls with 75 °C water. After 30 minutes, this
water contained up to 2 ppb bisphenol A.
Why use water for all these studies when one earlier FDA study went
so far as to assay migration from baby bottles into juice and
infant formula? "Unfortunately," says Natan, such foods can "hide
BPA from detection," masking the magnitude of any migration. He
says Arizono stayed with water to be sure he could detect even
small traces of the adulterant.
Natan's assessment was "reasonable," an FDA scientist acknowledged,
speaking on the condition that he not be named. When testing "a
more complex matrix [than water] -- the apple juice, or infant
formula -- we have a much higher detection limit," he explained.
In fact, he pointed out, when working with those foods, FDA
chemists had difficulty finding adulterant concentrations any lower
than 100 ppb. However, he told Science News OnLine, foods or
simulated foods "generally exaggerate what will actually migrate
into a real food" -- meaning it should identify a worst-case upper
bound on risk, provided any migration exceeds the detection
threshold.
Since those earlier studies, FDA's detection threshold has been
dropping. In one analysis of infant formula, published a year ago,
it found 13 to 15 parts per billion of bisphenol A in the drink,
with most of the hormone mimic coming from the cans' internal
coating. Newer, unpublished data by the agency's chemists have also
detected the migration of bisphenol A into some vegetables from
food-can linings. Here, the foods accumulated between 5 and 39 ppb
of the pollutant, the FDA reports.
The new Japanese study also looked at bisphenol-A migration from
the resin used to line food cans. In Japan, vending machines
dispense tea and coffee. Arizono explains that these canned drinks
have become the Japanese snack-drink corollary to Coke and Pepsi in
the United States. Though soft drinks stored in plastic-lined cans
picked up less than 1 ppb of bisphenol A, oolong tea acquired at
least 7 ppb -- and coffee a whopping 90 to 127 ppb. The
manufacturer reformulated its coffee containers as a result of
this study, Arizono notes.
New actions
Concerned by these new data, together with bisphenol-A toxicity
studies conducted in animals, the National Environmental Trust
joined with 11 other consumer, health, religious and environmental
organizations in petitioning FDA to:
+ promptly identify all constituents of plastic food containers
having the potential to migrate into foods to which children
are routinely exposed,
+ implement a strategy to eliminate or reduce children's
exposure to such materials, especially bisphenol A,
+ allow leached materials from plastic to remain in the food
supply "only after [manufacturers] have provided substantial
affirmative evidence of safety -- a burden that is not to be
met upon a showing merely of an absence of evidence of harm,"
+ and work with other federal agencies, such as the EPA and the
National Toxicology Program, to investigate possible low-dose
effects of such materials leaching from plastics.
To date, FDA has not formally responded to the petition.
The Society of the Plastics Industry (SPI), however, has responded.
It challenges the consortium's campaign, saying: "Over four decades
of research show that polycarbonate food containers and baby
bottles are safe." Moreover, one spokesman notes, since parents
have made the switch from glass to plastic drink bottles, children
suffer fewer dangerous accidents. Finally, SPI argues that small
quantities of bisphenol A pose no health hazard, so the leaching of
trace amounts should not be used to scare consumers.
In fact, there is considerable difference of opinion about the
significance of biological changes seen in animals exposed to
bisphenol A. In some cases, adults that had been exposed to the
hormonelike substance during fetal development showed curious
abnormalities. For instance, Frederick S. vom Saal at the
University of Missouri-Columbia has reported that the prostates of
some mice fetally exposed to 2 ppb bisphenol A were larger than
normal, though no cancers were present. So, arguments have erupted
on the significance of such changes.
Despite several attempts, plastics industry scientists have also
failed to replicate vom Saal's findings. There has been
considerable acrimony at scientific meetings between industry
scientists and vom Saal about whether they are all using the
appropriate methodology to probe for effects.
Clearly, the jury is still out.
Until a verdict is returned, what can a cautious parent do?
The National Environmental Trust recommends switching to baby
bottles and foodware that is not made from polycarbonates. For
instance, baby bottles manufactured from a pliable, milky-colored
plastic contain no polycarbonates.
Natan advocates that people who prefer to go on using
polycarbonates should consider discarding any that show obvious
signs of wear, such as a somewhat cloudy, crackled appearance. He
also recommends heating foods and drinks outside of the plastics
and then transferring them into the plastic only after they are
cool enough to eat or drink.
Related Readings:
Biles, J.E., et al. 1997. Determination of bisphenol-A in
reusable polycarbonate food-contact plastics and migration to
food-simulating liquids. Journal of Agricultural and Food
Chemistry 45(September):3541.
Hileman, B. 1999. Bisphenol A: Regulatory, scientific puzzle
-- concerns about health effects of estrogen mimic trigger a
flurry of intense research. Chemical and Engineering News 75
(March 24):37.
Raloff, J. 1997. Dental sealant safety reconsidered. Science
News 152(Nov. 22):324.
http://www.sciencenews.org/sn_arc97/11_22_97/fob1.htm
_____. 1997. A pollutant that can alter growth. Science News
152(Oct. 18):255.
_____. 1997. Lacing food with an estrogen mimic. Science News
152(Oct. 18):255.
_____. 1996. Estrogenic agents leach from dental sealant.
Science News 149(Apr. 6):214.
_____. 1995. Additional sources of dietary estrogens. Science
News 147(June 3):341.
_____. 1993. Plastics may shed chemical estrogens. Science
News 144(July 3):12.
Takao, Y., ... and K. Arizono. 1999. Fast screening for
Bisphenol A in environmental water and in food by solid-phase
microextraction. Journal of Health Science 45:39.
vom Saal, F.S., et al. 1998. A physiologically based approach
to the study of bisphenol A and other estrogenic chemicals on
the size of reproductive organs, daily sperm production, and
behavior. Toxicology and Industrial Health 14
(January-March):239.
1999. Baby alert: New findings about plastics. Consumer
Reports 64(May): 28.
Sources:
Koji Arizono
Faculty of Environmental and Symbiotic Sciences
Prefectural University Kumamoto
Kumamoto
JAPAN
Tom Natan
National Environmental Trust
1200 18 Street, N.W.
Washington, D.C. 20036
Society of the Plastics Industry
1801 K Street, N.W., Suite 600 K
Washington, DC 20006-1301
Web sites: http://www.socplas.org
http://www.plasticsinfo.org
http://www.bisphenol-a.org
Ruth Welch
FDA Press Office
H.F.S. 555
200 C Street, SW
Washington, D.C. 20204
Prepared by Janet Raloff, senior editor of Science News.
July 24, 1999
Copyright (c) 1999 Science Service. All rights reserved.
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