[Pharmwaste] Pete Myers interview on asthma, prostate cancer and endocrine disruptors

[Tenace, Laurie]

http://www.loe.org/shows/shows.htm?programID=07-P13-00015#feature3
"Living On Earth" interviews Dr. Pete Myers - not exactly PPCPs in waste, but
some interesting studies linking asthma and prostate cancer to exposure to
endocrine disruptors.

New Studies Link Asthma, Prostate Cancer to Toxic Chemicals
CURWOOD: It's Living on Earth. I'm Steve Curwood. Despite advances in modern
medicine two epidemics seem to be growing; those of prostate cancer and of
asthma. Now there are some provocative new studies that link these diseases
to exposure to tiny amounts of pollutants. One study finds that low-level
exposure to the chemical bisphenol A found in some plastic bottles and some
food cans can promote certain prostate cancers. That study has just been
published in the Journal Molecular Cancer Therapeutics.

The other study indicates tiny amounts of pesticides and PCBs that mimic
estrogen can stimulate the process of allergic reactions, most notably
asthma. That's reported in the current issue of Environmental Health
Perspectives. Joining me now to talk about this emerging research is Dr. Pete
Myers. He's the chief scientist for Environmental Health Sciences, which
publishes the online journal Environmental Health News.

Hello, Dr. Myers.

MYERS: Hi Steve, how are you today?

CURWOOD: Good. Now the first study we're going to look at, the researchers
for this one found a link between certain environmental contaminants that
mimic estrogen and allergic reactions including asthma. What's going on here?

MYERS: Well the big question out there is why are so many allergic diseases
increasing. Asthma's increasing. Allergies to things like peanuts is
increasing. It's really an epidemic of allergic disease. And scientists have
been looking for clues about what could be driving this. And this new study
shines a very bright light on one possible explanation. Our immune system
depends upon estrogen signals to adjust how sensitive it is. A little bit
more estrogen and your immune system becomes a little bit more sensitive. And
so what these scientists did, was a different type of question. They
recognize that there are actually chemicals in the environment that behave
like estrogen. And so they began to perform a series of experiments where
they took cells from mice and from people and they looked at the effective
exposure to these estrogenic chemicals on the sensitivity of the cells immune
systems. And low and behold they found a very very strong effect.

CURWOOD: So what kind of environmental contaminants are we talking about
here? Where are they found and how do they wind up in our bodies?

    
In one study, human prostate tumor cells were implanted in mice, which were
then exposed to Bisphenol A. (Courtesy of NIH) 
 
MYERS: Well, these contaminants are a series of persistent organic
pollutants: old pesticides, DDT, DDE. Things that have lingered, been used
for a long time in the environment, even if they're not being used now. But
because they are persistent they still make it into our food supply.

CURWOOD: Now, why has it taken so long to figure this out? What is it about
the effects of these chemicals that makes it hard to see the link between
allergic reactions and these chemicals that act like estrogens?

MYERS: Well first of all you have to think that the question is relevant. And
it's taken a while for the scientists who work on these types of issues
simply to ask about the potential contribution of estrogenic substances to
allergic disease. But now that they've started asking the questions they've
discovered a very interesting aspect of how these contaminants alter immune
system function. What they're seeing is that really low doses ratchet up
immune system sensitivity but that higher doses shut it down. And that dose
response relationship is both something that's relatively new to toxicology
but it's also one that's hard to investigate.

CURWOOD: So, wait a minute. You're telling me that someone who was exposed to
a lot of DDT it wouldn't have affected their allergic response to something
but if it was just a little bit it would?

MYERS: Well, it isn't so much that a high dose wouldn't have affected it. A
high dose would shut it down. Think about the surge protector that you use
for your computer. Your computer needs electricity but if all of a sudden too
much comes through it shuts down the system. Well that's the sort of thing
that appears to be happening here. Our immune system has to be able to
respond to the signals that the body naturally sends it. Those signals are
taking place at really low levels. As they increase the reactivity of the
immune system rises. But if all of the sudden there is a surge that's
unexpectedly high, the system shuts down and that's what appears to be
happening.

CURWOOD: So that is very confusing if you're doing research and you're just
looking at the chemical and its effect it's paradoxical. Sometimes it works
and sometimes it doesn't.

MYERS: It is. It's been one of the great challenges to research in this area
and especially to how we go about establishing health standards. Typically
the toxicological tests that are used to figure out whether this compound is
safe and at what level it is safe. They begin at high doses and then they
work down until they don't see an effect. Well if the chemical that you're
working on at low doses causes an increase and at high doses causes a
suppression you're not going to be asking the right questions.

CURWOOD: Dr. Myers I know the study didn't look at this at all but the asthma
epidemic is really big in cities and really big among poor people. What
questions would you want to ask as a researcher to link that prevalence of
disease in those populations to what is being found in this research?

MYERS: That's a great question, Steve and all the science isn't in on the
answer yet. But there are a couple of clues that we can take from this. One
is that the biggest source of exposure to these things is dietary. Diets that
are high in fat are more likely to expose you to some of the persistent
contaminants that this study focused on. The other thing that science is
pointing toward is the fact that cheaper grade construction materials often
contain compounds that the science links to increased immune system
sensitivity.

CURWOOD: In other words your house could be causing you asthma.

MYERS: Your house definitely could be causing you asthma. There have been
some very interesting studies looking at the composition of dust in houses
and the relationship to risk of asthma and there are significant associations
being found.

CURWOOD: And so what does this research suggest? I mean, what's the big
picture here in terms of asthma?

MYERS: Well, the big picture is this: we know that we're in the middle of an
asthma epidemic. And people have been struggling with the question. Why are
we seeing this? Why is asthma increasing at a time when for the most part air
quality has been getting better? The answer this study suggests is it isn't
that there's more pollution, it's that we're more sensitive to the pollution
that's there. Our immune system is responding more strongly to the irritants
that have been around the whole time. It's just that we're more sensitive to
them now.

CURWOOD: Let's take a look now at that other study that considers tiny doses
of toxic substances and this is the one that links prostate cancer to
bisphenol A, which is commonly found in plastic bottles and the lining of
some food cans. Now I understand that this study shows that tiny amounts of
the toxin can interfere with a common treatment for prostate cancer. How did
they come to that conclusion?

MYERS: What these scientists did was they implanted prostate tumor cells from
people into mice. And then they looked at the effect of exposing those mice
to bisphenol A. And what they found was that bisphenol A made the cells
switch into a state where they couldn't be controlled by the normal way
physicians manage prostate cancer.

CURWOOD: How could BPA interfere with prostate cancer treatment?

MYERS: Well, normally when a guy has prostate cancer it turns out that those
tumors need testosterone to divide and grow. And that's a condition that's
called Androgen Dependence. Testosterone is an androgen. So, if the physician
can either lower the guy's circulating testosterone levels or somehow make
him less sensitive to testosterone using pharmaceuticals they can keep the
tumor under control. So what this new science tells us is that if the tumor
is exposed to bisphenol A, it shifts. All the sudden it's no longer dependent
on testosterone to proliferate.

CURWOOD: How do you avoid bisphenol A? I understand it's in 95 percent of us.

MYERS: It's in 95 percent of us but not all at the same levels. I've taken
one very practical step which is I avoid canned food. I also don't use those
wildly popular sports bottles that are made out of polycarbonate plastic.
There are ways that individuals can decrease their exposures. There's no
question about that.

CURWOOD: Ok, so we've got this one new study from the University of
Cincinnati that finds a link between bisphenol A and prostate cancer. And
then we've got the other new study from the University of Galveston that we
talked about earlier, linking some persistent organic pollutants with asthma.
So, tell me Dr. Myers what do these two studies say about the chemicals we're
being exposed to on a daily basis and our general health.

MYERS: Well they say two things. They say that the health standards that we
have developed over the last 30 years are in the scientific Jurassic. They
just haven't been asking the right questions. But they say something else
which I find very encouraging. The science is telling us that if we pay
attention to it and we start making individual choices and societal choices
about how we manage these chemicals and how we work to avoid exposures we can
probably prevent some of the diseases that here to for we hadn't thought were
preventable. That's pretty exciting.

CURWOOD: Dr. Pete Myers is chief scientist for Environmental Health Sciences
in Charlottesville, Virginia. They publish Environmental Health News. Thank
you so much sir.

MYERS: Thank you, Steve.

CURWOOD: You can find references for this research and a link for the
Environmental Health News site at loe dot o-r-g.

Laurie J. Tenace
Environmental Specialist
Florida Department of Environmental Protection
2600 Blair Stone Road, MS 4555
Tallahassee, Florida 32399-2400
PH: (850) 245-8759
FAX: (850) 245-8811
Laurie.Tenace at dep.state.fl.us 

Mercury web pages:
http://www.dep.state.fl.us/waste/categories/mercury/default.htm

Unwanted Medications web pages:
http://www.dep.state.fl.us/waste/categories/medications/default.htm




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