e., one year of Central European sun). Under this condition, the polymer degraded to expose, but not necessarily release, free CNTs. Recently, a study was published which conducted an initial, task-based comparative assessment to determine the potential for release of carbon nanofibers (CNFs) during dry material handling, wet cutting, grinding, and sanding (by machine and hand) of plastic composite material containing CNFs (Methner et al., 2012). Using a combination of direct reading instruments and filter-based air sampling methods for airborne mass and

TEM, concentrations were measured and characterized near sources of particle generation, in the breathing zone of the workers, and in the general work area. Tasks such as surface grinding of composite material and manually transferring dry CNFs produced substantial increases in particle number concentration. MDV3100 molecular weight Concomitant increases in mass concentration were also associated with most tasks. Over 90%, i.e. 12 out of 13 samples taken during abrasion of CNF composites examined via TEM, indicated that releases of CNFs do occur, mainly as agglomerated CNF, and that the potential for exposure exists, although exposure levels were not quantified. Degradation of the polymer/CNT matrix potentially provides key step(s)

in the release of CNTs in all phases of the life cycle including manufacturing, product or article life/usage and end of life. Several other recent papers have provided useful discussions of polymer nanocomposite degradation, LDN-193189 concentration including polymer CNT composites (Nguyen et al., 2011, Petersen et al., 2011 and Wohlleben et al., 2011). The potentially important role of abrasion in the release of nanoparticles from polymer matrices has been discussed by Wohlleben and coworkers (Wohlleben et al., 2011). Abrasion increases exposure to polymer-CNT simply by enhancing surface area isometheptene to mass. In addition to these direct effects, the creation of much smaller particles also enhances dispersion by atmospheric and aquatic routes. Degradation generally decreases the

tensile strength of the polymer matrix thus increasing its susceptibility to abrasion and breakdown to small particles, i.e. referred to as the “chalking” phenomenon in some cases (Wohlleben et al., 2011). Fragmentation to smaller particles can in turn increase exposure to light and hydrolytic and/or microbial breakdown. However, current results have shown that nanoparticles remain associated with the debris that results from sanding of polyoxymethylene and polyamide with embedded inorganic nanoparticles (Wohlleben et al., 2011). So far, one generic release scenario for CNTs in composites has been published (Nowack et al., 2012). These authors have evaluated how different environmental conditions affect the alteration of the composite material, as well as the transformation of the CNTs once they are released from the composite.