Fig. 7

Effect of ENM solubilization on DG-predicted dose metrics. Solid ENM mass exposure concentration (in bottom 10 μm) and dissolved ENM concentrations predicted by DG model under different solubilization scenarios for ZnO (C ₀ = 0.01 mg ml⁻¹, column height = 3 mm, d _H = volume-averaged mean (Table 1)) for 24 h. a, b, ZnO solid mass exposure concentration (mg ml⁻¹ in bottom 10 μm of well) and solubilized ZnO concentration (mg ml⁻¹) for initial solubilization to 0, 30, 60 and 90 μM (0.0, 2.442, 7.327 and 4.885 μg ml⁻¹, dissolved fraction = 0.0, 0.2442, 0.4485, and 0.7327) with no further dissolution during transport. c, d, solid mass and dissolved exposure concentrations with initial solubility of 20 μM (1.63 μg/ml, dissolved fraction = 0.163) and continuous constant dissolution of 0, 2, 4 and 6 μM h⁻¹ (0.0, 0.16, 0.32 and 0.48 μg ml⁻¹ h⁻¹, fraction dissolved = 0.0, 0.016, 0.032 and 0.048 h⁻¹), e, f, solid and dissolved exposure mass concentrations with initial solubility of 20 μM and further linear increase in dissolution up to 12 h to maximum total dissolution of 20, 30, 60 and 90 μM (1.63, 2.442, 7.327 and 4.885 μg ml⁻¹, dissolved fraction = 0.163, 0.2442, 0.4485, 0.7327) at 12 h and remaining constant after 12 h.