Hemolysis caused by titanium dioxide particles.

Washed human erythrocytes were incubated with titanium dioxide (TiO2) particles at 37 degrees C for 1 hr and hemolysis was determined by the percentage of hemoglobin released (optical density at 540 nm; OD540) from the cells. Effects of TiO2 on OD540 were corrected and dose-response curves were analyzed by the Hill plot. Judging from the estimated dose to cause 50% hemolysis, the anatase form of micron-scale (<5000 nm) particles was 73 and 11 times more potent than the amorphous (<50 nm) and rutile (<5000 nm) forms, respectively, whereas it was 1.