Brief Comments on the Health, Safety, Environmental and Social issues
section of Nanotechnology: views of Scientists and Engineer
- Please be advised that I have read the Nanotechnology document and focused
primarily on the Health, Safety and Environmental section. The document represents
a reasonable high-cut summary of the issues. I wonder whether the Commission
will be focusing on more specific issues over time.
- I was surprised that the Commission Members seemed to be more focused on
the potential similarities between carbon nanotubes and asbestos fibers (see
below). I think that this is a mistake and that there is little similarity
between these two materials. In this regard, the composition, physical dimensions,
known toxicological behaviors, aerodynamic behavior, and agglomeration tendencies
are very different- and it seems to me that the comparison of carbon nanotubes
(CNT) to asbestos stems more from the paucity of safety and toxicity data
on CNT (fear of the unknown) as opposed to any documented similar physical
characteristics that would link nanotubes and asbestos fibers with regard
to their impact on the lung.
- I was also surprised by the lack of concern by the Commission Members regarding
the pulmonary toxicity of nanoscale nonfibrous particulates. In the Toxicology
world, concerns regarding the pulmonary toxicity of ultrafine or nanoparticles
are getting much more attention from a safety standpoint. I believe that the
common perception of nano or ultrafine particles (i.e., < 100 nm) producing
enhanced pulmonary toxicity or lung inflammogenic effects when compared to
fine-sized particles (size range = > 0.1 mm – 3.0 mm) of identical
composition are based primarily upon the toxicological database of 3 particle-types:
namely, titanium dioxide, carbon black particles, and diesel exhaust particles.
This database is rather sparse – and I think that we are likely to determine
in the next few years that the health risks of nanoparticles are also strongly
influenced by 1) surface coatings on particles; as well as 2) factoring in
“species differences in lung responses to inhaled particulates”
– because a) the rat model is the most sensitive species, and b) the
lung responses of rats to particulates is different from other rodent species
and VERY DIFFERENT from the responses of large mammalian species, such as
dogs, primates, and humans.
David B. Warheit, Ph.D.
DuPont Haskell Laboratory for Health and Environmental Sciences