NIEHS Director Birnbaum: "We kind of jump from the proverbial fry pan into the fire" when replacing chemicals

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Nov. 20, 2009
By Jane Kay, Environmental Health News
http://www.environmentalhealthnews.org/ehs/news/q-a-with-linda-birnbaum

Nearly a year ago, toxicologist Linda Birnbaum was named director of
the National Institute of Environmental Health Sciences and the
National Toxicology Program. She sat down with Environmental Health
News journalist Jane Kay in San Francisco on Wednesday to answer
questions about the environmental health risks we face today.

As head of the federal institute examining environmental health,
Birnbaum and her staff are taking on many controversial topics,
including Bisphenol A and new flame retardants in consumer products.
She explains how scientists are trying to figure out what role
chemicals and contaminants may play in breast cancer and other
diseases and health problems.

"I’m concerned about some of the plasticizers, including phthalates,
and some of the flame retardants, especially the alternative ones,"
she said. "In this country, we kind of jump from the proverbial fry
pan into the fire without thinking about the alternative."

Q: You say if you don’t ask the right questions in science, you are
not going to find the answers. Your agency has just dedicated $30
million to study bisphenol A, the estrogenic chemical found in
polycarbonate bottles and food can linings. What are some of the
questions we should be asking about bisphenol A and what are we doing
to get the answers?
A: The $30 million program that we have on bisphenol A is looking at
what can bisphenol A do, especially developmental exposures: At what
doses do these effects occur and how serious are they? Some focus is
on epidemiology but much of it is animal experimentation. We brought
all of these investigators together in October to facilitate
collaboration – sharing of samples, standards. We’re emphasizing that
we really need to look at the low-dose effects. We’re looking at many
different targets – the mammary gland, the prostate and immune and
cardiovascular systems. Bisphenol A has often been called a weak
estrogen. But it’s going to do some things that estrogen doesn’t do.
So we have to look more broadly.

There are two recent human studies, one showing an effect on
cardiovascular disease and one Kaiser Permanente study on workers in
China (in polycarbonate-manufacturing plants) showing effects on male
sexual function. Their occupational health standards are not as
stringent as ours, and so there was a much higher exposure in that
population. It’s kind of a new observation. The adult male effects are
very interesting because we’ve seen similar effects in our animal
studies. That strengthens my confidence in the new study. It needs to
be repeated in another population, and we need a better understanding
of how high the exposures really were in that population.

Q: Bisphenol A has attracted a lot of public and scientific attention.
What other contaminants deserve that sort of attention?
A: Anything where we have wide exposures in the population. Bisphenol
A is not a persistent chemical. If it stopped being made, it would
rapidly go away. Chemicals that are very persistent, we all need to
look at because they are not going to go away. Sixty to 70 percent of
the PCBs made are still out there. The levels are lower in our bodies
than in our parents’ bodies, but PCBs are going to be around for a
long time. I’m concerned about some of the plasticizers, including
phthalates, and some of the flame retardants, especially the
alternative ones. They’ve now found chlorinated tris that was banned
in babies’ pajamas 30 years ago in high levels in sediments. It’s a
real concern. It’s used in carpet padding and cushion foam, and it’s
being found in house dust. So people are being exposed. In this
country, we kind of jump from the proverbial fry pan into the fire
without thinking about the alternative.

Q: The Food and Drug Administration has said it will announce a new
policy statement on bisphenol A by the end of the month. What do you
expect?
A: I think the FDA is looking at the newest science, and I think it is
going to take some time for that to happen. I don’t expect the FDA to
come out and say the information is conclusive that bisphenol A is
safe. All the regulatory agencies are beginning to realize it’s
important to update approaches and look at all of the available
science. The guidelines from the past may not be addressing questions
we’re asking today.

Q: Which exposures in everyday life do you consider the greatest risk
factors for breast cancer?
A: Some of our greatest risk factors are obesity because of the excess
estrogen associated with it. We know that women who are obese have a
greater risk of breast cancer. If we’re talking about environmental
chemicals, we know there are pharmaceutical exposures that may
predispose women to breast cancer later on. We know hormone
replacement therapy is associated with an increase in breast cancer.
Since the report that it did cause breast cancer and many women have
stopped taking hormone replacement therapy, we’ve seen a decrease in
breast-cancer incidence, exactly what you’d predict for our
understanding of how estrogens work. I have concerns about early-life
exposures, and how that may predispose for breast cancer later on. We
know that exposing animals in utero, or during the infantile period,
or puberty or pregnancy can alter the breast responsiveness and change
what may happen later on. When you have cells rapidly dividing and
differentiating, that is the time they are especially vulnerable to
the effects of chemicals. If you expose an organ in utero or in the
infantile period, it may never develop normally.

Q: What recent research funded by NIEHS shows the most promise for
disease prevention in the near term?
A: We have developed sensors to measure exposures. If we know what
people are exposed to, then we can prevent the exposures. With
bisphenol A, where is it all coming from? It’s not just baby bottles.
It’s not just cans. How is it getting into us? Is it getting into our
food, in our drinking water, in our house dust? Let’s identify the
major sources of exposure, and work to control those. The very minor
sources may not be an issue. NIEHS identified the BRCA1 and BRCA2
genes, which has furthered breast cancer research. There is also the
“sister study” of 51,000 women followed for 10 years looking at
nutrition, lifestyle, exposure to environmental chemicals and
biological markers.

Q: What are we doing to answer the big questions: Are chemicals in the
environment increasing breast cancer, reproductive diseases and
neurodevelop-mental/behavioral problems?
A: We’re addressing it at this point very much on a one-chemical-at-a-
time basis. We need to begin to develop strategies to look more
broadly because no one’s exposed to one chemical at a time. And we
need a better understanding of whether the whole suite of chemicals in
our bodies is associated with the problems. Nobody’s trying to look at
the sum total. A study I’m trying to encourage is where you’d make a
mix of what’s in the American population and expose animals to that
mix. Maybe I would start in by looking at the high-end of the
population. If we saw something in our animals, that would certainly
be a concern. Now if we didn’t see anything, that doesn’t mean things
aren’t happening. But I think it would be a study worth doing.

Q: Do you still have concerns about people’s exposures to the
brominated flame retardants, PBDEs?
A: Yes. There is no convincing evidence that PBDEs are declining in
people or wildlife in the United States. It’s too soon. Manufacturers
stopped production of penta and octa in 2004. The chemicals are still
getting into the environment from existing products. Deca continues to
be produced. Until recently, scientists didn’t measure deca in people.
Deca rapidly metabolizes in people and wildlife but is very stable in
the environment. PBDEs look as though they are on the decline in
Europe where they were never used as widely as in North America. The
European Union banned them in 2004. Germany banned them in the 1980s,
and Sweden stopped use in the early 1990s. The peak levels in Swedish
women occurred around 1997, and have since declined.

Q: Many experts talk about the “data gap” when it comes to our
knowledge of the risks of chemicals. How substantial are these gaps
and how can we fill them? What new testing should be required?
A: Some [gaps] we can fill by testing, and some by doing specific
studies. We have to prioritize the data gaps of the greatest concern.
As the first toxicologist heading NIEHS, I will bring in exposure
science. Toxicology is a hybrid science that examines the safety of
different exposures using all the tools of molecular biology,
analytical chemistry, biochemistry, physiology and pathology. Today’s
toxicology is not our grandparents’ toxicology. It’s not the old-
fashioned “dose ‘em and count ‘em.” I would like to see any study done
on animals get a measure of the internal dose so we can compare the
animal results to humans. We need to know if the levels in
experimental animals that are associated with effects are similar to
the levels that we’re finding in people. If the levels where we see
effects in the animals are similar, or within a factor of 10 or more
than we see in people, then I think we should be concerned. The
standard tagline was “the dose makes the poison.” But it’s the dose
and the timing that’s critical. Different things happen at different
doses.

Q: You have said, “Animals may not be people. But people are animals.”
Can you explain what you mean by that?
A: Nature is inherently conservative. So many of the basic processes
that govern development and physiology in fish, for example, are the
same processes that occur in human beings. Some people are concerned
whether rats or mice, or in some cases, cats or dogs or non-human
primates, are good models for humans. If we have chemicals that cause
a multiplicity of effects in several species, why would we think that
some people are not going to be susceptible to the effects?

For more information on Linda Birnbaum, go to
http://www.niehs.nih.gov/about/od/director/index.cfm
Jane Kay, who has been an environmental journalist for more than 20
years, can be reached at J aneKayEnvironment @gmail.com