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"Airborne engineered nanomaterials present complex
exposure measurement challenges," Maynard said. "Conventional
approaches - measuring the mass of airborne material - will not always
be sufficient. This presents a challenge because studies have
indicated that, on a mass-for-mass basis, certain nanometer-scale
particles may be more toxic than larger particles with a similar
composition. In other words, smaller particles may be more harmful
than conventional thinking would lead us to believe."
Maynard and Aitken reduced the incredibly diverse
set of possible engineered nanoparticles into nine distinct categories,
ranging from very simple spherical particles to complex
multifunctional particles. By pairing these categories with particle
properties associated with potential health effects, they teased out
possible monitoring approaches for each particle-property combination.
"What our analysis shows is that in the complex new
'nano world' there is no single or simple method for monitoring
nanoaerosol exposures in order to assess and manage potential health
effects," Aitken explained. "There are instruments that present
partial solutions to the measurement challenges we face. But at the
end of the day, we lack the tools and devices that are sophisticated,
cost-effective and fast enough to do the job."
Maynard and Aitken conclude that current approaches
of measuring the number of particles in a volume of air, surface areas,
and mass concentration, will all be useful to some degree. However,
further research is needed to identify which is most important for
specific nanomaterials and which measurement methods are most
effective.
The authors advocate developing a new "universal
aerosol monitor" capable of providing detailed information on the
nature of airborne engineered nanomaterials to which people are
exposed. Maynard, Aitken and 12 other experts included development of
such a versatile measurement tool among five grand challenges that
they viewed as essential to achieving the safe handling of
nanotechnology in an article that appeared in the November 16, 2006
issue of the journal Nature.
The proposed wearable sampling device would measure
aerosol number, surface area, and concentration mass simultaneously
and would be low cost. Today, stand-alone instruments can perform the
individual types of measurements called for by Maynard and Aitken. "Bringing
these technologies together into a single package within the size and
cost parameters discussed does present a significant challenge," they
write.
"An economical integrated device will empower small
and large nanotechnology industries alike to reduce uncertainty over
what their workers are exposed to, and enable them to develop safer
working environments" said Maynard. "This will require targeted
research into developing new methodologies and new instruments. But
the rapid advancement and commercialization of nanotechnologies are
leading to the need for effective - if not necessarily perfect -
exposure measurement approaches and devices to be developed as soon as
possible."
In 2005, nanotechnology was incorporated into $30
billion in manufactured goods - a number predicted to grow to $2.6
trillion in annual manufactured goods by 2014. Already, there are
almost 400 manufacturer-identified nanotechnology-based consumer
products on the market - ranging from computer chips to automobile
parts and from clothing to cosmetics and dietary supplements.
Nanotechnology is the ability to measure, see,
manipulate and manufacture things usually between 1 and 100 nanometers.
A nanometer is one billionth of a meter; a human hair is roughly
100,000 nanometers wide. |
