Table 1. Percentages of nuclei in hypodiploid, diploid, hyperdiploid, tetraploid and hypertetraploid classes based on DNA content.
| Chrysotile concentration | Recoveryperiod | hypodiploid% (n) | diploid% (n) | hyperdiploid% (n) | tetraploid% (n) | hypertetraploid% (n) |
| Control cells | 3.83 (46) | 58.92 (707) | 20.17 (242) | 16.83 (202) | 0.25 (3) | |
| 250 µg/ml | 2 days | 8.83 (106) | 28.75 (345) | 29.08 (349) | 26.27 (320) | 7.4 (89) |
| 4 days | 5.83 (70) | 31.67 (380) | 27.58 (331) | 26.17 (314) | 9.17 (110) | |
| 8 days | 5.92 (71) | 31.08 (373) | 29.83 (358) | 22.58 (271) | 10.58 (127) | |
| 125 µg/ml | 2 days | 5.50 (66) | 35.08 (421) | 32.17 (386) | 22.75 (273) | 4.5 (54) |
| 4 days | 5.50 (66) | 43.0 (516) | 20.92 (251) | 26.17 (314) | 4.42 (53) | |
| 8 days | 4.50 (54) | 53.42 (641) | 16.42 (197) | 20.08 (241) | 5.58 (67) | |
| 62.5 µg/ml | 2 days | 8.0 (96) | 44.5 (534) | 26.42 (317) | 17.58 (211) | 3.5 (42) |
| 4 days | 7.67 (92) | 45.75 (549) | 19.33 (232) | 23.83 (286) | 3.42 (41) | |
| 8 days | 4.50 (54) | 51.17 (614) | 15.42 (185) | 24.25 (291) | 4.67 (56) |
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<0.001).