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Comparative carcinogenicity study of a thick, straight-type and a thin, tangled-type multi-walled carbon nanotube administered by intra-tracheal instillation in the rat

2020; BioMed Central; Volume: 17; Issue: 1 Linguagem: Inglês

10.1186/s12989-020-00382-y

1743-8977

Dina Saleh, William Alexander, Takamasa Numano, Omnia Hosny Mohamed Ahmed, Sivagami Gunasekaran, David B. Alexander, Mohamed Abdelgied, Ahmed M. El‐Gazzar, Hiroshi Takase, Jiegou Xu, Aya Naiki‐Ito, Satoru Takahashi, Akihiko Hirose, Makoto Ohnishi, Jun Kanno, Hiroyuki Tsuda,

Carbon Nanotubes in Composites

Abstract Background Multi-walled carbon nanotubes can be divided into two general subtypes: tangled and straight. MWCNT-N (60 nm in diameter) and MWCNT-7 (80–90 nm in diameter) are straight-type MWCNTs, and similarly to asbestos, both are carcinogenic to the lung and pleura when administered to rats via the airway. Injection of straight-type MWCNTs into the peritoneal cavity also induces the development of mesothelioma, however, injection of tangled-type MWCNTs into the peritoneal cavity does not induce carcinogenesis. To investigate these effects in the lung we conducted a 2-year comparative study of the potential carcinogenicities of a straight-type MWCNT, MWCNT-A (approximately 150 nm in diameter), and a tangled-type MWCNT, MWCNT-B (7.4 nm in diameter) after administration into the rat lung. Crocidolite asbestos was used as the reference material, and rats administered vehicle were used as the controls. Test materials were administered by intra-Tracheal Intra-Pulmonary Spraying (TIPS) once a week over a 7 week period (8 administrations from day 1 to day 50), followed by a 2-year observation period without further treatment. Rats were administered total doses of 0.5 or 1.0 mg MWCNT-A and MWCNT-B or 1.0 mg asbestos. Results There was no difference in survival between any of the groups. The rats administered MWCNT-A or asbestos did not have a significant increase in bronchiolo-alveolar hyperplasia or tumors in the lung. However, the rats administered MWCNT-B did have significantly elevated incidences of bronchiolo-alveolar hyperplasia and tumors in the lung: the incidence of bronchiolo-alveolar hyperplasia was 0/20, 6/20, and 9/20 in the vehicle, 0.5 mg MWCNT-B, and 1.0 mg MWCNT-B groups, respectively, and the incidence of adenoma and adenocarcinoma combined was 1/19, 5/20, and 7/20 in the vehicle, 0.5 mg MWCNT-B, and 1.0 mg MWCNT-B groups, respectively. Malignant pleural mesothelioma was not induced in any of the groups. Conclusions The results of this initial study indicate that tangled-type MWCNT-B is carcinogenic to the rat lung when administered via the airway, and that straight-type MWCNT-A did not have higher carcinogenic potential in the rat lung than tangled-type MWCNT-B.