The genotoxic effect of hexavalent potassium dichromate (K
2Cr
2O
7) was investigated in mice
in vivo using sister chromatid exchange (SCE) and chromosomal aberration analysis. K
2Cr
2O
7 induced a significant increase in the frequency of SCE's after intraperitoneal (i.p.) treatment with the doses 6, 12, 24 mg kg
-1b.wt. which correspond to 1/8, 1/4 and 1/2 of the experimental LD
50. The lowest tested dose 3 mg kg
-1b.wt. had no effect with respect to SCE's and its effect reached 6.57 ± 0.36/cell compared with 5.80± 0.55/cell for the control. The frequency of SCE's reached 9.03 ±0.20 after treatment with the highest tested dose of K
2Cr
2O
7, a value which is less than that induced by mitomycin C (13.10 ± 0.40) as the positive control. Thiola at the concentrations of 20 and 50 mg kg
-1b.wt. had moderate but non-significant effect for minimizing the frequency of SCE's induced by different doses of K
2Cr
2O
7.
With respect to chromosomal aberrations, all the tested concentrations of K
2Cr
2O
7 (3, 6, 12, 24 mg kg
-1b.wt.) induced a significant increase in the percentage of chromosomal aberrations in mouse bone marrow as well as in mouse spermatocytes 24 h after single i.p. treatment. The incidence of chromosomal damage increased significantly with increasing the dose. However mitomycin C induced higher effect. The results also show that the pretreatment with thiola at the dose of 50 mg kg
-1b.wt. significantly reduced the percentage of chromosomal aberrations induced by K
2Cr
2O
7 in all the treatment groups and the results confirm the protective role of thiola which has been proved previously against the genotoxicity of some mutagens.
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