Figure 2.

The effect of eight particles on the viability of HASM cells after correcting for the optical interference of particles. (a) At the doses tested, TiO₂, DEP, FS and WF caused little change in cell viability. (b) CuO NPs, but not MPs, caused dose-dependent decrease in viability. (a) and (b) have the same x-axis. (c) Both ZnO NPs and MPs impaired cell viability, with the former being more toxic. Also shown here is the soluble ZnCl₂. In this and all subsequent figures, an asterisk indicates statistically significant difference from the negative control (p < 0.01). (a) Lines with open circles, TiO₂; lines with open inverted triangles, DEP; lines with stars, FS; lines with open diamonds, WF. (b) Lines with open squares, CuO^{5 μm}; lines with filled squares, CuO^{50 nm}. (c) Lines with open triangles, ZnO^{44 μm}; lines with filled triangles, ZnO^{40 nm}; lines with crosses, ZnCl₂ (the actual mass dose was scaled by MW_ZnO/MW_ZnCl2 to match the zinc concentration; MW, molecular weight).