[Pharmwaste] Plastic (bisphenol A) ingested, study finds - Scientists rebut federal finding on baby safety

[DeBiasi,Deborah]

Original Story URL:
http://www.jsonline.com/story/index.aspx?id=710303
 



Plastic ingested, study finds 
Scientists rebut federal finding on baby safety

By SUSANNE RUST
srust at journalsentinel.com

Posted: Jan. 22, 2008

Scientists furious at conclusions reached by a federal panel charged
with assessing the safety of a common household chemical have
retaliated. And they're using science as their weapon.

In a paper released online this month in the journal Reproductive
Toxicology, a team of researchers at the University of Missouri
published a study that strikes at the core of the panel's findings on
bisphenol A, a chemical found in baby bottles and the linings of food
cans.

The researchers have shown that the panel's decision to disregard dozens
of studies in which animals were exposed to the chemical via injections,
instead of through the mouth or stomach, was specious. And they are
calling on the government to re-evaluate, or dismiss, the panel's
conclusions.

In November, the Center for the Evaluation of Risks to Human
Reproduction released a report on bisphenol A that minimized concern
about the chemical after reviewing more than 700 studies published over
the past 30 years.

Hundreds of studies have shown that this chemical can cause a host of
maladies, including breast cancer, testicular cancer, diabetes,
hyperactivity, obesity, low sperm counts and miscarriage in laboratory
animals. The chemical has been detected in 93% of Americans tested.

In December, the Journal Sentinel found that the panel's report, written
by 12 scientists appointed by the National Institute of Environment
Sciences, gave more weight to industry-funded studies and more leeway to
industry-funded researchers. The newspaper found that the panel missed
dozens of studies publicly available that the newspaper found online
using a medical research Internet search engine.

This latest research exposes one of the major criticisms raised against
the panel - namely, the decision to throw away, or give only marginal
weight, to studies in which animals were injected with bisphenol A, as
opposed to getting it through the mouth or stomach.

The panel wrote that because people are most likely exposed to bisphenol
A by the mouth, when it leaches into canned foods or liquids consumed in
clear plastic bottles, it's the only relevant way to expose animals. 

It also cited research showing that when adult animals and people ingest
bisphenol A, enzymes in the liver make the chemical inactive. However,
when adult animals are injected with the chemical, this route is
bypassed, and they show much higher concentrations.

Some studies ignored
This decision caused the panel to consider more than 40 government and
academic studies as inadequate, or of only limited value. 

One of these papers, published in 2003 and funded by the Japanese
government, found that bisphenol A could disrupt the development of
female reproductive organs in mice that were exposed in utero. The panel
considered it of only limited value, because the mother mice were
injected with the chemical.

Another study, funded by the National Institutes of Health, showed that
mice exposed in utero had a higher propensity to have prostate lesions
than animals that were not exposed. Again, this study was considered of
only limited value because the animals were not exposed orally.

In response, Frederick vom Saal, a biologist at the University of
Missouri-Columbia and a vocal critic of the panel, decided to test the
panel's assumption.

"Their decision was absurd," he said.

"First of all, fetuses don't eat," he said. "Anything in maternal blood
will freely cross the placenta. And unless the chemical is immediately
cleared out of the mother's system, which it isn't, that blood will go
immediately to the baby."

In addition, fetuses and newborns lack, or express at low levels, the
liver enzyme that deactivates the chemical.

"This is not news," said vom Saal. "Pediatricians will tell you, babies
are not little adults. They do not process chemicals the same way adults
do."

To demonstrate this, vom Saal and fellow researchers Wade Welshons and
Juliet Taylor exposed 3-day-old female mice to bisphenol A. They
separated the mice into four groups.

Two groups were exposed to the chemical through the mouth - one group
received a high dose, the other a low dose. Two other groups received
injections - again, one high and one low.

Animals were killed at intervals over the next 24 hours, and
concentrations of bisphenol A in the blood were measured.

The team found no difference between animals that had received the
chemical orally or via injection.

"It wasn't just that there was no difference," said vom Saal. "It was
exactly the same."

Vom Saal said that both people and rodents have this particular enzyme,
and in both cases, fetuses and newborns do not express it at the same
level as adults.

This new research has the potential to upset the panel's findings, said
Gail Prins, a researcher at the University of Illinois at Chicago who
has been critical of the panel's report.

The bottom line
She said that what really matters in these studies is the concentration
of biologically active bisphenol A in the blood, irrespective of how it
got there. Animals should have concentrations that are similar to what
is found in people, because that is what is relevant in these studies.

However, Robert Chapin, the chairman of the panel, and an executive at
Pfizer, said the new research "stands in contrast to a number of other
studies that show the opposite." He said it was those other studies that
"led us to the logical conclusion we reached."

When asked to supply the citations for those studies, he said he could
not remember them offhand. He also said that if other scientists could
replicate vom Saal's work "and provide a rational explanation for the
sudden shift," the panel would reconvene and reconsider its position.

Prins said her lab will take up that challenge immediately.

The Journal Sentinel reviewed the panel's report and found several
studies that showed differences between oral and non-oral exposures in
adult animals, but none that looked at newborns. 

When asked to respond to the Missouri study, L. Earl Gray Jr., an
Environmental Protection Agency toxicologist and a member of the panel,
forwarded a study funded by the American Plastics Society. He said the
study, which was reviewed by the panel, suggested that newborn mice have
enough of the liver enzyme to deactivate bisphenol A at low doses. 

However, the authors of the study, who were from Dow Chemical, reported
that 4-day-old mice had a 10- to 18-fold higher concentration of
biologically active bisphenol A in their blood than adults - a finding
that vom Saal and Prins say supports their contention.

"They had this information right there," said Prins. "Yet, they ignored
it."

Michael Shelby, director of the government agency that selected the
panel to evaluate bisphenol A, said his program will take all public
comments and new publications into consideration before preparing the
National Toxicology Program's final report on the chemical. 

The Toxicology Program will use the panel's report, as well as other
research, as a guide for its own final report on bisphenol A.

"We recognize that there are concerns about the issue of route of
exposure," he said, "and we will give careful consideration to all the
scientific evidence available to us on this issue."




>From the Jan. 23, 2008 editions of the Milwaukee Journal Sentinel 


Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
PPCPs, EDCs, and Microconstituents
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