The results of these safety assessments have mainly reported on the lung carcinogenicity of the biomaterial and were intended to prevent lung cancer in those exposed to asbestos. It is clear from reports in the literature that inhaled MWCNTs can translocate to the circulatory system.11,12 However, the in vivo kinetics of MWCNTs remains largely unknown, and the safety assessment for the translocation of inhaled MWCNTs from the circulatory system to other organs is an important and understudied subject that would benefit from further research.