Fig 11. Effects on the gastrointestinal tract (Caco-2 intestinal cells).

The cytotoxic and cytostatic effects were evaluated by Colony Forming Efficiency Assay (CFE) in Caco-2 cells exposed to 100 μg/ml of TiO₂ (NM-103 and NM-104) (A) and SiO₂ (NM-200 and NM-203) (B) for 3 (short exposure) and 10 days (long term, repeated-dose exposure). The results are expressed as CFE (% of solvent control) = ([average No. of treatment colonies/average No. of solvent control colonies] × 100). The solvent control (0.05% BSA) did not induce cytotoxicity. Data are reported as means ± SEM (standard error mean = standard deviation/√number of replicates). One-way analysis of variance (ANOVA) with post hoc test (Dunnett's Multiple Comparison Test) for comparing groups of data versus one control group was used (** p<0.01; *** p<0.001).