Fig. 6.

Cell viability of A549 cells exposed to MWCNT. Cells were treated with increasing doses of MWCNT (range dose 10–80 μg/cm² for REF, O-REF and A-REF; 80 μg/cm² for NM-401). After 48 h cell viability was determined with the resazurin assay. 0, control untreated cells. Data are means ± SD of 6 indipendent determinations obtained in two separate experiments. **p < 0.01, ***p < 0.001 vs. control, untreated cells (0); $$p < 0.01, $$$p < 0.001 vs. equivalent doses of REF.