Fig. 6.

DNA strand break levels in the liver tissue (% tail DNA) detected by comet assay following intratracheal instillation of 162 μg of TiO₂, CeO₂, CB measured 1, 28 and 180 days after exposure. Particle exposed groups n = 9, vehicle control n = 9. All values are presented as mean + SD. Asterisks (**) denote P ≤ 0.01, (***) denote P ≤ 0.001 of DNA SB level in exposed groups versus vehicle control. Hashtags (##) denote P ≤ 0.01, (###) denote P ≤ 0.001 of DNA SB level in TiO₂ vs CB groups. Cross (†) denotes P ≤ 0.05 of DNA SB level in CeO₂ vs CB groups