Respiratory toxicity of carbon nanotubes

Abstract

Carbon nanotubes (CNT) are emblematic nanomaterials, and have generated a highly competitive international scientific research activity. Since their initial description in 1991, the understanding of their unique physicochemical properties led to a large number of actual applications and uses, as well as future developments. Because of these promising applications, there is an increasing concern regarding the consequences that could result from human exposure to CNT. Analysis of the existing literature shows that respiratory exposure to CNT can lead to the occurrence of pulmonary inflammation, the formation of granuloma, and the development of pulmonary fibrosis. The exact determinants of these effects still remain to be clearly identified, although intrinsic physicochemical characteristics of CNT (i.e. length, dispersion status, and residual catalyst content) seem to be of importance. Several critical issues still remain to be solved, such as the translocation of CNT outside the lungs and the occurrence of their biotransformation, which should open a new understanding to the respiratory effects of CNT.