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FEATURE STORY 69
cadmium selenide, which can be toxic as a bulk material,
so researchers encase them in a protective coating. But it is
not yet known whether the dots will linger in the body, or
whether the coating will degrade, releasing its cargo.
Sensible regulation of nanoparticles will require new
methods for assessing toxicity, which take into account the
qualitative di erences between nanoparticles and other regu-
lated chemicals. Preferably, those methods will be generally
applicable to a wide spectrum of materials.
Today s assays are not adequate for the purpose, says
Oberdörster. "We have to formalize a tiered approach," he
says, "beginning with noncellular studies to determine the
reactivity of particles, then moving on to in vitro cellular
studies, and nally in vivo studies in animals. We have to
establish that some particles are benign and others are reac-
tive, then benchmark new particles against them."
Separately testing every newly developed type of
nanoparticle would be a Herculean task, so Rice s Colvin
wants to develop a model that indicates whether a particu-
lar nanoparticle deser ves special screening. "My dream
is that there would be a predictive algorithm that would
say, for a certain size and surface coating, this particular
type of material is one you d want to stay away from," she
says. "We should be able to do it, with the advance we
have made in computing power, but we have to ask the
right questions. For instance, is it acute cytotoxicity, or is
it something else?"
Amidst all the uncertainty about evaluating nanopar-
ticles toxicity, regulatory agencies are in something of a
quandary. In the United States, the Food and Drug Admin-
istration will assess medical products that incorporate
nanoparticles, such as the quantum dots now being tested
in animals; the Occupational Safety and Health Adminis-
tration is responsible for the workplace environment in the
factories that make the products involving nanoparticles;
and the Environmental Protection Agency looks at prod-
ucts or chemicals that broadly permeate the environment,
like additives to diesel fuel. In principle, these federal agen-
cies have sweeping power over nanomaterials, but at the
moment, their traditional focus, their limited resources, and
the sheer lack of test tube and clinical data make e ective
oversight next to impossible.
For example, the National Institute for Occupational
Safety and Health, the part of the Centers for Disease Con-
trol and Prevention in Atlanta responsible for studying and
tracking workplace safety, acknowledges that "minimal
information" is available on the health risks of making
nanomaterials. The agency also points out that there are
no reliable gures on the number of workers exposed to
The EPA seems further along. In its draft "Nanotech-
nology White Paper," issued in December, it proposed inter-
agency negotiations to hammer out standards and pool
resources. It acknowledged that at present, some nanopar-
ticles that should be under its review are not, because they
are not included in the inventory of chemicals controlled
under the Toxic Substances Control Act.
The EPA must defend the safety not only of human beings
but of the natural environment---plants and ecological systems
that may be exposed to a regulated material. There is scant
data on the e ects of nanomaterials in the environment, but
some of it is troubling. One study, for example, showed that
alumina nanoparticles, which are already commonly used,
inhibit root growth in some plants.
In a report written for the Project on Emerging Tech-
nologies, J. Clarence Davies, assistant administrator for
policy, planning, and evaluation at the EPA from 1989 to
1991, advocates passing a new law assigning responsibility
for nanomaterial regulation to a single interagency regula-
tory authority. Davies would also require manufacturers to
prove their nanotech products safe until enough evidence
had been gained to warrant exemptions.
But some executives in the nanotech industry cringe at
the prospect of such regulations. Alan Gotcher, head of Altair
Nanotechnologies, a manufacturer in Reno, NV, that makes
various types of nanoparticles, testi ed before the U.S. Sen-
ate in Febr uary and cited the Davies report. "To fall into a
one-size- ts-all approach to nanotechnology," he said, "is
irresponsible and counterproductive." Gotcher would prefer
a government-funded e ort to amass the necessary data and
build the necessary models before setting any standards.
It is doubtful, however, that the nanotech community
will stop developing new products, or that the public will
stop buying them, while awaiting a new regulatory frame-
work that could take years and millions of dollars to nalize.
While few agree on how to e ciently determine the toxicity
of nanoparticles, or how to regulate them, nearly everyone
agrees on the urgency of quickly tackling both questions.
The use of nanoparticles in consumer products like cos-
metics and cleaners represents only a tiny sliver of nanotech s
potential, but any unresolved safety concerns could cast a
huge shadow. "If I was someone producing these materials,
I would be afraid that one health problem, anywhere, would
hurt the entire industry," says Peter Hoet, a toxicologist at
the Catholic University of Leuven, in Belgium.
The large consumer corporations DuPont and Procter
and Gamble participated in a study on nanoparticles
toxicity. But the nanotech community needs to put pres-
sure on manufacturers using the "nano" label for market-
ing purposes to stand up and take responsibility for their
products. That means contributing resources and money to
toxicity studies and freely disclosing which nanotechnolo-
gies they are relying on.
Philip E. Ross writes on science and technology from New York City.
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