In order to investigate the relative involvement of the different DNA repair pathways NHEJ, HRR and BER in repair of DNA lesions of different complexity, we have compared clonogenic survival and induction of micronuclei in a panel of repair-deficient CHO cell lines after exposure to γ-rays and α-particle radiation. The complexity of the DNA lesions formed was also modified by exposures to 2 M DMSO, a potent radical scavenger, which is known to interact with the lesions produced by direct hits on DNA.

The NHEJ pathway gained the most from scavenging of the free radicals after irradiation to γ-rays or α-particles as evaluated by cell survival and the yields of MN. Results presented here also implicate that clustered base damages were induced by α-radiation and contributed to the yield of DNA double-strand breaks.