Micronucleus induction by chromium and selenium, and suppression by metallothionein inducer.

The clastogenic effects of chromium compounds (CrCl3 and K2CrO4) and selenium compounds (H2SeO3 and Na2SeO4) in mouse bone marrow cells have been investigated. K2CrO4 induced significant, dose-related increases in micronuclei. H2SeO3 also showed a significant micronucleus induction at the highest dose. CrCl3 and Na2SeO4 were negative for micronuclei induction in mice. The suppressive effect of Bi(NO3)3, a metallothionein inducer, on the micronucleus induction by K2CrO4 and H2SeO3 has been also investigated. Pretreatment with Bi(NO3)3 suppressed the micronucleus induction by K2CrO4 and H2SeO3. In addition, the incidence of micronucleus induction seemed to be reduced by double dosing with K2CrO4 and H2SeO3, compared to single dosing. It is generally recognized that a number of metal compounds induce metallothionein synthesis. These results suggest that the mechanism of suppression of micronucleus induction by K2CrO4 and H2SeO3 involve possible participation of metallothionein in mouse bone marrow.