Carbon nanotubes: A review on risks assessment, mechanism of toxicity and future directives to prevent health implication

Abstract

Carbon nanotubes (CNTs) have tremendous applications in almost every walk of life; however, their harmful impacts on humans and the environment are not well addressed. CNTs have been used in various applications ranging from medical science to different engineering branches, to ease human life. Generally, the toxicological profile of CNTs under laboratory conditions cannot be assessed primarily in medical science due to the inconsistent availability of cytotoxic study data. CNT toxicity has been affected by many physicochemical properties (e.g., size, type of functionalization), concentration, the extent of exposure, mode of exposure, and even the solvents/medium used to dissolve/disperse CNTs for their application. These inconsistencies arise due to the variation in synthesis methods as well as the mode of their human exposure. Besides their unlimited use in various fields, most of CNT toxicity aspects and mechanisms remain uncertain. Additionally, in-depth knowledge of CNTs toxicity is scarce, and the available literature shows dissimilarities in experimental data and exposure studies. To understand the toxicological issues, it is the need of the hour to provide insight into the published data, post-exposure studies, and various factors that may damage the cells due to CNTs toxicity. This review article analyses the hazardous potential through toxicological implications and summarizes the detailed mechanism(s) of CNTs studied on the different model organisms, including human cell lines. In this review article, we hypothesized that thorough knowledge of various aspects, as mentioned above, helps us design and develop possible strategies to reduce the toxicity of nanomaterial to make them safer and secure for humanity’s betterment.