Assessing cellular responses to milled recycled carbon fiber in alveolar macrophages

Carbon fibers and their composites are finding their way into applications in a variety of industrial fields; however, insight into the safety of carbon fibers remains scarce. In this study, the cytotoxicity of milled recycled carbon fiber was examined using NR8383 cells (alveolar macrophages) in a comparison with multi-walled/single-walled carbon nanotubes and carbon black nanoparticles. Following exposure, no significant cytotoxicity or metabolic inhibition of milled recycled carbon fiber was evident. Phagocytosis into macrophage cells was observed, but which significantly increased NO production, indicative of macrophage cell activation. No significant effect on intracellular reactive oxygen species production or the inflammatory response occurred at the gene expression level. Although milled recycled carbon fibers are taken up into cells and affect NO production, other cellular responses were smaller compared with those of carbon nanotubes and carbon black. The reason for the smaller responses and the effects on other cellular processes require further study.