Percentages of nuclei in hypodiploid, diploid, hyperdiploid, tetraploid and hypertetraploid classes based on DNA content.

Nuclear DNA content of control and chrysotile (250 µg/ml, 125 µg/ml or 62.5 µg/ml) -treated HK2 cells (for 48 h) allowed to recover in fiber-free medium for 2, 4 and 8 days was quantified. The nuclei were then divided into the following 5 classes: hypodiploid (DNA content ≤1.49 C), diploid (DNA content between 1.5 C and 2.39 C), hyperdiploid (DNA content between 2.4 C and 3.59 C), tetraploid (DNA content between 3.6 C and 5.1 C), and hypertetraploid (DNA content >5.1 C). For the control group and each treatment group, 1200 nuclei were analyzed. When compared to control cells, all chrysotile treatments led to hypertetraploid nuclei formation (P