[Pharmwaste] determining potential health risks from phthalates

Tenace, Laurie Laurie.Tenace at dep.state.fl.us
Fri Dec 19 09:28:25 EST 2008


http://www.sciencenews.org/view/generic/id/39447/title/EPA_should_test_demasc
ulinizing_pollutants_collectively


EPA has what it needs to determine phthalate toxicity, NRC says 

Cumulative effects of phthalates and related compounds will be larger than
effects measured one chemical at a time, reports a National Research Council
panel
By Janet Raloff 
Thursday, December 18th, 2008   On December 18, a National Research Council
panel told the Environmental Protection Agency that existing data are plenty
for determining the potential health risks posed by phthalates, among the
most ubiquitous pollutants on the planet. At the same time, the NRC panel
strongly recommended that the agency adopt a "paradigm shift" in the way it
assesses the chemicals' toxicity to humans.

Instead of evaluating each phthalate compound individually, EPA should begin
assessing risks from likely combos of these and related chemicals - even if
each chemical works differently, according to the panel's new report. 

Phthalates are a widely used family of plasticizers and solvents. Owing to
the chemicals' presence in plastics, cosmetics, personal care products and
even medicines, residues of these chemicals show up in everyone throughout
the developed world. 

For more than a decade, studies in rodents have been demonstrating that
exposures to phthalates early in life can perturb - in some cases derail -
development of an animal's reproductive organs (SN: 9/2/00, p. 152). Males
are most sensitive, largely because these chemicals act as anti-androgens.
That is, the chemicals lower concentrations of testosterone, the primary male
sex hormone. Especially concerning: In females, phthalates can cross the
placenta and pollute the womb.

The NRC panel advocated that EPA assess cumulative risks from all phthalates
and other anti-androgenic compounds together - even if the way each pollutant
depresses testosterone action or availability results from differing modes of
action.

Whether these pollutants pose serious risks to people remains an open
question, acknowledged several authors of the NRC report, who took part in a
teleconference for the report's release.

EPA didn't ask NRC to assess phthalates' toxicity to humans, notes Deborah
Cory-Slechta of the University of Rochester School of Medicine and Dentistry
in New York. Instead, EPA asked her panel to evaluate whether sufficient data
exist to conduct a human risk assessment. And if so, how should the risks be
evaluated: on the basis of single compounds considered separately, as a group
evaluated together, or as a group assessed along with additional
anti-androgenic agents.

Cory-Slechta says her panel found that there are plenty of data for EPA "to
go ahead and do it [a human risk assessment]." But the panel also recommended
that when EPA does such an assessment, it should take a sharply different
tack from its normal approach. 

To Shanna Swan, a phthalate researcher at the University of Rochester, the
recommended change in how to calculate the risk of these chemicals "is a big
deal. Cumulative risk assessment is the way it must be done," she says,
"given the dose additivity of these chemicals and the multiplicity of our
exposures."

Most people regularly encounter many phthalates, and as a class these
compounds tend to have similar impacts. So, even if each of five phthalates
had no apparent effects at a particular dose when delivered individually,
coincident exposure to the mix might easily prove to compound the toxicity,
the new report explained.

Indeed, published data show that "phthalates can work together at quite low
doses," noted NRC panel member Andreas Kortenkamp of the University of London
School of Pharmacy in England. "So if combination effects were not taken into
consideration at this level, we would underestimate possible risks." In fact,
he said, his committee's new paradigm for considering phthalate toxicity
cumulatively must inevitably result in findings of higher risks than would
have been calculated by assessing each chemical in isolation.

In the new report, NRC concluded that a lifelong testosterone shortfall
triggered by phthalate exposures can cause "the variety of effects observed"
in animals - including infertility, reduced sperm production, undescended
testes, penile birth defects and other reproductive-tract malformations - "if
it occurs at times that are critical for male reproductive development." The
most sensitive exposure period: time in the womb.

Indeed, concentrations of phthalates measured in amniotic fluid in the human
womb can be "in the range of levels in rat amniotic fluid that gives rise to
adverse effects in the offspring," Kortenkamp said. 

However, links to human effects have been quite limited, observes panel
member Paul Foster of the National Institute of Environmental Health Sciences
in Research Triangle Park, N.C. One exception: a study of infant boys linking
phthalate exposure in the womb to a feminization of the anogenital distance -
the span separating the gonads and anus (SN: 6/4/05, p. 355).

In rodents, this distance is demonstrably longer in males. In fact,
researchers depend on this sex-linked distance to visually determine the
gender of young rodents. 

Follow-up studies are needed with more subjects to test the validity of those
preliminary data, Foster says. That said, this phthalates toxicologist points
out that the general processes by which these chemicals interfere with sexual
differentiation "are common to all mammals. And so, having seen them in rats,
one would not expect them not to occur in humans - providing, of course, the
exposure was high enough."


Laurie Tenace
Environmental Specialist
Waste Reduction Section
Florida Department of Environmental Protection
2600 Blair Stone Rd., MS 4555
Tallahassee FL 32399-2400
P: 850.245.8759
F: 850.245.8811

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