Table 3.
DNA strand break levels (% tail DNA) in liver tissue following intratracheal instillation, intravenous injection and oral gavage of 162 μg of TiO2, CeO2 or CB NPs 1, 28 and 180 days after the exposure determined by the Comet assay
| DNA SB in the liver following intratracheal instillation | ||||
| Control | TiO2 | CeO2 | CB | |
| day 1 | 4.1 ± 4.6 | 4.3 ± 1.5 | 3.7 ± 1.4 | 5.6 ± 3.7 |
| day 28 | 3.0 ± 1.4 | 2.9 ± 0.8 | 5.2 ± 5.9 | 9.4 ± 7.2**## |
| day 180 | 3.5 ± 0.8 | 3.4 ± 1.0 | 5.5 ± 2.4 | 12.2 ± 8.7***###† |
| DNA SB in the liver following intravenous injection | ||||
| Control | TiO2 | CeO2 | CB | |
| day 1 | 3.1 ± 0.9 | 3.0 ± 1.0 | 3.7 ± 1.1 | 17.9 ± 7.9***###††† |
| day 28 | 5.2 ± 4.0 | 3.6 ± 1.1 | 9.7 ± 4.9 | 16.1 ± 10.2***### |
| day 180 | 3.3 ± 0.7 | 5.8 ± 7.2 | 3.7 ± 2.0 | 22.8 ± 11.1***###††† |
| DNA SB in the liver following oral gavage | ||||
| Control | TiO2 | CeO2 | CB | |
| day 1 | 5.5 ± 3.8 | 4.6 ± 3.5 | 7.9 ± 8.6 | 13.9 ± 10.4 |
| day 28 | 3.0 ± 0.6 | 2.8 ± 0.6 | 3.3 ± 0.7 | 2.4 ± 0.6 |
| day 180 | 2.8 ± 0.8 | 3.5 ± 0.9 | 3.8 ± 3.5 | 7.2 ± 6.5 |
Particle exposed groups n = 9, vehicle control n = 9. All values are presented as mean ± SD. Asterisks (**) denote P ≤ 0.01, (***) P ≤ 0.001 of DNA SB levels in exposed groups versus vehicle control. Hashtags (##) denote P ≤ 0.01 and (###) P ≤ 0.001 of DNA SB levels in the CB groups compared to TiO2 groups. Cross (†) denotes P ≤ 0.05, (†††) P ≤ 0.001 of DNA SB levels in the CB groups compared to CeO2 groups