Carbon nanotube toxicity: The smallest biggest debate in medical care

Figures & data

Figure 1. Main types of carbon nanotubes.

Table 1. Current studies carried out; each study describe its methodology, aims, and results, and whether single walled CNT (SWCNT) or multiple walled CNT (MWCNT) were used as a substrate in study

Title of study	Method (in vivo or in vitro)	Aims/results	Toxicity measured/determined
Dispersion of single-walled carbon nanotubes by a natural lung surfactant for pulmonary in vitro and in vivo toxicity studies	Both in vivo and in vitro	The study aimed to create a simple and rapid method of nanoparticle dispersion using a natural lung surfactant and to evaluate the effect of dispersion status of SWCNT on cytotoxicity and fibrogenicitin vitro and in vivo	SWCNT
2010		Wang et al. (2010)
Epithelial–mesenchymal transition involved in pulmonary fibrosis induced by multi-walled carbon nanotubes via TGF-beta/Smad signaling pathway	In vivo and in vitro	Studies the relationship between pulmonary fibrosis and different lengths of MWCNT, both short and long	MWCNT
	MWCNT used as substrate	MWCNT used as substrate
2014		Chen et al. (2014)

Figure 2. Toxicity of carbon nanotubes on lung.

Table 2. Summary of the studies related to CNTs toxicity in different organisms

Organism tested	Types of CNTs	LOEC	EC 50	Mechanism of toxicity
Chlorella vulgaris	Pristine CNT	0.053 mg L^−1	1.8 mg L^−1	Oxidative stress, agglomeration and physical interactions (Schwab et al., 2011)
	MWCNT of diameter 10, 20–40 nm, and 60–100 nm	NA	41.0, 12.7, and 12.4 mg L^−1, respectively	Oxidative stress, agglomeration and physical interactions (Long, Ji, Yang, Lin, & Wu, 2012)
Pseudokirchneriella subcapitata	Pristine CNT	0.053 mg L^−1	2.5 mg L^−1	Oxidative stress, agglomeration and physical interactions (Schwab et al., 2011)
	SWCNT	0.25 mg L^−1	NA	Oxidative stress, agglomeration and physical interactions (Youn et al., 2012)
Dunaliella tertiolecta	MWCNT	NA	0.8 mg L^−1	Oxidative stress and photosynthesis inhibition (Wei et al., 2010)
Daphnia magna	MWCNT grafted with polyethyleneimine	NA	25 mg L^−1	Increased size of the surface Coating (Khalid, Hussain, Suman, & Arun, 2016)
Ceriodaphnia dubia	MWCNT resuspended in NOM	0.25 mg L^−1	NA	Agglomeration (Li & Huang, 2011)
Xenopus leavis larvae	DWCNT	10 mg L^−1	NA	Physical interactions (Bourdiol et al., 2013)
Sprague–Dawley rat	1,000 mg kg^−1 of SWCNT from gestation day 6–19	NA	NA	No teratogenicity (Lim et al., 2011)

Notes: LOEC: least observable effect concentration; EC 50: effective concentration 50; NOEC: no observed effect concentration; NOM: natural organic matter.

Table 3. Adverse effects of single walled CNT in relation to the adverse effects that may arise from the extensive use of MWCNT

Single walled (SW) CNT	Multiple walled (MW) CNT
Induces malignancy in stem cells by chronic exposure to CNTs	Differences in cytotoxicity, genotoxic, and inflammatory response of bronchial and alveolar human lung epithelial cells
Inflammatory response of immortalised and primary human lung epithelial cells	Severe fibrotic peritoneal adhesions, fibrotic peritoneal thickening, and a high incidence of macroscopic peritoneal tumors (Chen et al., 2014)
In vitro Inhibition of HEK 293 cell proliferation (Herzog et al., 2009)	In vitro Induce cell cycle arrest and increase apoptosis/necrosis of human skin fibroblasts (Liu et al., 2009)

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Lim, J. H., Kim, S. H., Lee, I. C., Moon, C., Kim, S. H., Shin, D. H., … Kim, J. C. (2011). Evaluation of maternal toxicity in rats exposed to multi-wall carbon nanotubes during pregnancy. Environmental Health and Toxicology, 26, e2011006.10.5620/eht.2011.26.e2011006

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