“…Our findings indicate that inorganic arsenic induces homologous recombination, with retention of the downstream copy of exon 7 of the hprt gene in the SPD8 cell line, which is consistent with the involvement of a chromatid exchange mechanism. In light of previous observations that cells in the S-phase are most sensitive to the cytotoxicity of arsenic [Gurley et al, 1986], which also arrests cells in this phase [Peters et al, 1976;Yager and Wiencke, 1997], the enhanced recombination frequency observed here may be related to inhibition of DNA replication and the subsequent formation of strand breaks. The homologous recombination induced by Cobalt[II] is probably related to its clastogenic ability to induce DNA strand breaks and chromosomal aberrations, as well as SCEs [Hartwig, 1995].…”