Microscopical Analysis of Consumer Products Containing Carbon Nanotubes: Determining Potential Airborne Release

Steven P. Compton, Ph.D. and Michelle R. Cavaliere, Ph.D.

It has been estimated that by 2014, $2.6 trillion in manufactured goods will incorporate nanotechnology, which is approximately 15% of total global output. In particular, carbon nanotubes (CNTs) have been incorporated into a wide variety of commercially available materials due to their unique properties. With increasing numbers of consumer products containing nanomaterials, especially carbon nanotubes, groups including manufacturers, consumers, and regulatory agencies have become concerned with the issue of potential nanoparticle exposure and the possible health risks associated with exposure. We are currently developing several methods that can be employed to test consumer products for exposure risks. This study focuses on airborne exposure from consumer products like air filters, which have the potential to release respirable CNTs during normal operation. A two-fold approach to studying the potential for CNT release has been employed.

Conclusions:

• Complementary microscopical techniques confirmed the composition of the filters to be carbon fibers and carbon nanotubes, with one filter having an aluminosilicate backing material.
• Carbon nanotubes were heterogeneously dispersed throughout the activated carbon fiber matrix and easily detected by TEM, SEM , and confocal Raman microscopy.
• A single CNT structure was detected from one cassette filter, which was below the detection limit.
• Aciniform soot and spores were detected as extraneous materials on one cassette filter.