Viability and IL-1β release following 24-h exposure to TiO
nanobelts in transformed human THP-1 cell line. A) Mean ± SEM percent LDH release relative to total cell lysis. B) Mean ± SEM percent viable cells relative to no particle control. C) Mean ± SEM IL-1β release. Asterisks indicate significance at ***P < 0.001, **P < 0.01, or *P < 0.05 compared to no particle 0 μg/ml condition. Daggers indicate significance at ††† P < 0.001, †† P < 0.01 or † P < 0.05 compared to the TiO2 -COOH nanobelt (TNB COOH) at the same concentration. Symbols §§ indicate significance at P < 0.01 compared to the humic acid TiO2 nanobelt (TNB HA) condition at the same concentration.