Fig. 6

Frequency of micronucleated cells in 2000 binucleated cells (MNCs/2000 BNCs) and replication index (RI) after a 48-h exposure of BEAS-2B cells to coarse (A–J), medium (B–K) and fine (C–L) size fractions of U-CNF (A–C), T-CNF (D–F), C-CNF (G–I) and E-CNF (J–L). Data are presented as the mean ± se (N = 2 independent replicates). Asterisks designate statistically significant differences compared with the untreated cultures at ***p < 0.001 and ****p < 0.0001. Daggers designate statistically significant linear regression at ^††††p < 0.0001. The positive control, MMC (150 ng/ml), induced a statistically significant increase in the frequency of micronucleated cells over the negative control values in all the experiments performed (21.59 ± 1.80-fold increase; p < 0.01; 27.6 ± 3.5% RI) confirming the validity of the experiments (data not shown)