The induction of sister-chromatid exchanges in Chinese hamster ovary cells by K-region epoxides and some dihydrodiols derived from benz[a]anthracene, dibenz[a,c]anthracene and dibenz[a, h]anthracene.

Experiments were performed to investigate the effects of 3 polycyclic aromatic hydrocarbons, benz[a]anthracene, dibenz[a,c]anthracene and dibenz[a,h]anthracene and K-region epoxides and some of their related dihydrodiols on the chromosomes of Chinese hamster ovary cells in vitro. Of the 3 hydrocarbons only benz[a]anthracene showed any activity in inducing sister-chromatid exchanges. The K-region epoxide and the 3,4-dihydrodiol have been found to be more active than the corresponding K-region or the other non-K-region dihydrodiols derived from benz[a]anthracene. Although dibenz[a,c]anthracene was almost inactive, the K-region 5,6-epoxide and all 3 possible dihydrodiols, the 1,2- 3,4- and 10,11-diols were active in inducing increased numbers of sister-chromatid exchanges in the chromosomes of these cells. The 3,4-dihydrodiol of dibenz[a,h]anthracene was also active in inducing sister-chromatid exchanges whereas the 1,2- and 5,6-dihydrodiols were only weakly active. This study provides some support for the suggestion that the activation of these 3 hydrocarbons proceeds by the metabolic conversion of non-K-region dihydrodiols into vicinal diol-epoxides.