ABSTRACT
The model is extended to a consideration of the risk of chemical mutagens by combining the radiation-induced molecular lesion, the deoxyribonucleic acid (DNA) double strand break, with the paired double strand lesion block on DNA synthesis induced by UVB and UVC light. In the late 1970s and early 1980s, a considerable research effort was made to investigate synergism arising from the combination of various chemical agents with radiation. A wide variety of chemical mutagens is capable of forming DNA single strand lesions such as intra-strand cross-links, DNA-protein cross-links or alkylations. It is considered unlikely that a single strand lesion will be cytotoxic or mutagenic, unless it ‘pairs’ with a second single strand lesion to form a paired double strand lesion. The exposure of man to any mutagenic chemical potentially carries a cancer risk and should, therefore, be subject to strict control and regulation.
