Fig. 6

Stone particles induce sample- and concentration-dependent lysis of human erythrocytes. Human erythrocytes harvested from donors were exposed to 0–400 μg/mL quartzite, anorthosite, rhomb porphyry, dacite, quartz diorite, hornfels and α-quartz for 30 min. Free hemoglobin in the supernatant, an indicator of cell lysis, was detected by reading absorbance at 540 nm. Results are presented as mean ± SD (n = 4). Area under the curve (AUC) values in (b) were calculated from the values in (a) for the concentration-range of 0–400 μg/mL, and are presented related to equal mass (white bars) and surface area (grey bars). Statistical significance is based on a two-way ANOVA followed by Dunnet’s post-test (a) or a one-way ANOVA followed by Tukey post-test (b). Values in (a) were log-transformed prior to statistical analysis to satisfy model assumptions of normality and homoscedasticity. Asterisks (*) indicate statistically significant difference from the respective control (a), while a capped line indicates statistically significant difference between samples (b)