[Pharmwaste] Scientists tell EPA to analyze chemical risks
Laurie.Tenace at dep.state.fl.us
Wed Dec 24 09:09:03 EST 2008
Scientists to EPA: Risks of chemicals that alter male hormones should be
A national panel of experts says EPA must change its focus and analyze
chemicals that endanger male reproduction cumulatively or it will "seriously
underestimate" the risks to human health.
By Marla Cone
Editor in Chief
Environmental Health News
December 18, 2008
Concluding that nearly everybody is exposed to a mix of chemicals that could
be damaging male reproductive health, a national panel of scientists on
Thursday advised the U.S. Environmental Protection Agency to shift its focus
and group them together when judging how much of a danger they pose.
The committee, assembled by the National Academy of Sciences, looked
specifically at phthalates, controversial compounds widely found in consumer
products. Phthalates soften plastic to make vinyl for toys, building
materials, medical devices and other items, and they also are used in
fragrances and other beauty products.
The recommendation to combine the compounds when analyzing their threats to
human health would mark a critical change in EPA strategy. It would likely
lower the total amount of phthalates the agency considers safe for people and
ultimately could lead to strict regulations on their use.
By analyzing each chemical individually, the EPA underestimates the
health risks of phthalates, the committee reported. In human bodies,
phthalates combine, amplifying the effects on male reproduction.
"By only doing one, we underestimate the risk," said Deborah
Cory-Slechta, a professor of environmental medicine at University of
Rochester School of Medicine and Dentistry who chaired the National Research
Council's phthalates committee.
The recommendations could have far-reaching implications beyond
phthalates, transforming how the EPA determines to what degree people will be
exposed to a variety of chemicals and pollutants.
The committee said other compounds, such as pesticides, that also are
linked to effects on male hormones should be grouped with phthalates in the
EPA's risk analysis.
"A focus solely on phthalates to the exclusion of other antiandrogens would
be artificial and could seriously underestimate cumulative risk," the report
EPA scientists asked the National Academy of Sciences for advice on how to
assess phthalates because they knew many have the same effects.
Peter Preuss, director of the EPA's National Center for Environmental
Assessment, said his "best guess" is that the agency will conduct the
recommended cumulative assessment for phthalates. But he said his staff just
received the 160-page report and it must first analyze the technical details
of how the committee says to proceed. The EPA had been on a track to finish
its assessments of at least two phthalates in 2010.
"The Academy said very clearly that they think there is sufficient
information to do this, so that is our next step," Preuss said.
"There are many chemicals that act by many different mechanisms but the
final result is a series of impacts on the developing male reproductive
system," he said. "The Academy said these things are important-focus on the
endpoint, the [health] effect, and work from that. They are trying to
simplify this process."
Going even further, the scientists urged the EPA to consider broadening
all its assessments to include cumulative effects of compounds with the same
That, for example, might lead to combined analysis compounds that affect
the brain, female reproduction, lung cancer, or heart disease.
The report bolsters a relatively new scientific argument that cumulative
exposure of chemicals and pollutants should be considered when setting safe
doses for each.
Many environmental groups and public health experts have urged EPA to
conduct risk assessments that combine chemicals, so they welcomed the
Shanna Swan, director of the University of Rochester's Center for
Reproductive Epidemiology and one of the leading scientific experts on
phthalates, called the cumulative approach "the crucial next step" in
addressing environmental chemicals that disrupt hormones.
"It is extremely important to conduct cumulative risk assessments to
protect public health," added Dr. Sheela Sathyanarayana, assistant professor
of pediatrics at University of Washington. "Unlike in scientific
experiments, humans are exposed to multiple chemicals everyday," she said, so
combining the chemicals "can help identify how these multiple exposures could
be leading to health outcomes in the general population."
Swan and Sathyanarayana were not on the panel, but both have studied
phthalates. Sathyanarayana's research linked babies' phthalates to baby
lotions, powders and shampoos. Swan and her colleagues reported in 2005 that
the chemicals were associated with signs of feminized genitalia in newborn
Tests conducted by the U.S. Centers for Disease Control and Prevention
show that nearly all people carry traces of numerous phthalates in their
bodies. Fetuses, infants and children are considered most at risk.
Europe and the United States have restricted phthalates in toys and
other children's products, and the EU has banned some in cosmetics. But a
variety of phthalates are still in a host of consumer products.
A child may ingest phthalates through chewing on a rubber duck, an
infant may be exposed from intravenous tubes in neonatal wards, and a fetus
may absorb them through his mother's use of perfumes, lotions, nail polishes
and other cosmetics.
Industry groups have argued that there is insufficient evidence to group
But the panel of 13 scientists disagreed.
"Our committee concludes that there are common adverse effects" for many
phthalates and "we believe that EPA should go ahead and conduct a cumulative
risk assessment," Cory-Slechta said. She said the scientists found sufficient
data, primarily from laboratory animal tests, to justify the new approach for
"There is a growing body of literature, particularly in rats, showing
effects of phthalates on development of the male reproductive system," she
Several types of phthalates mimic or block testosterone and other
androgens, which are the sex hormones that guide formation of testicles,
sperm and other parts of the male reproductive system. In animal tests,
exposure leads to infertility, malformed penises and abnormal testicles,
which scientists call the "phthalate syndrome."
In the past, EPA has done cumulative risk assessments when substances
were structurally similar in their chemical makeup or acted in the same way.
But the committee says the EPA should instead group compounds according to
"what they ultimately do"-the effects on human health, Cory-Slechta said.
The American Chemistry Council, representing industries that produce
phthalates, said Thursday that it has "some reservations about how to conduct
the cumulative risk assessment on substances" that do not act in the same
"This is remarkably ambitious and could be problematic for EPA considering
that this essentially could result in a study without limits, financially or
otherwise," said Chris Bryant, managing director of the group's Chemical
Products & Technology Division.
"Congress has asked the Consumer Product Safety Commission to conduct a
cumulative risk assessment on phthalates and there is a question as to
whether a simultaneous EPA study would be redundant," he added.
The chemical industry also wonders how this would be reconciled with
another National Academy report earlier this month that advised EPA to more
strongly focus its risk assessments for chemicals.
Cory-Slechta agreed that a cumulative assessment would mean a "real
paradigm change for EPA" and "might prove somewhat challenging for them." One
obstacle for EPA scientists is that not all phthalates have the exact same
effects or the same potency.
"EPA certainly has been moving in the direction of cumulative risk
assessment, largely for chemicals structurally similar and ones that act in a
similar way. This is the next step-- focusing on adverse outcomes," she said.
"This committee believed very strongly that the conceptual approach should
be broadly applicable" to other chemicals, too, she added.
For instance, EPA could evaluate the risk of combined exposures to lead,
mercury, and polychlorinated biphenyls-all of which can damage developing
brains and reduce children's IQs, the committee said.
"The question is do we have enough data on the individual chemicals to put
into an assessment like this. For something like phthalates, the answer is
definitively yes," Sathyanarayana said. But, she added, "for other chemicals
that have not been researched as extensively, it may be difficult to find
specific information for let's say, fetal effects, and this point is
highlighted in the [committee's] summary."
One example where EPA does not have enough data to combine all the
compounds is nanoparticles, which is used in sunscreens and a variety of
consumer products, she said.
"Even though we may not have the data yet to do this for many classes of
chemicals, the recognition that this is necessary should help regulators move
towards acquiring the data needed to do this," Swan said.
The EPA's Preuss acknowledged that "there clearly will be challenges to
applying this to chemicals beyond the phthalates," even when looking at just
male reproduction. His staff will have to resolve questions about how much
scientific evidence is needed before including a chemical.
"We sort of have a role in the agency of doing the difficult assessments,"
he said. "Fitting something in like this with the current staffing we have is
one of the challenges, clearly."
Sathyanarayana agreed with the committee's recommendation to group
chemicals together according to what they do to the body, not just how they
"I think it is very important," she said. "This shift in focus could lead
to a much better assessment of how mixtures affect the development of adverse
Beyond male reproductive health, the committee's report raises
interesting questions about how Preuss' staff should determine a safe amount
of many chemicals, including a long list of air pollutants that can cause the
same respiratory and cardiovascular damage.
"I'm sure there will be a huge amount of discussion following up on this
report about how broadly we can apply the principles they recommend," Preuss
said. "I think it will be quite interesting and controversial."
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