Ratio of acentrics to dicentrics in human lymphocytes exposed to X rays and misonidazole.

A 0.8 mM concentration of misonidazole was added to human blood samples before exposure to graded X-ray single doses, in order to investigate the dependence of the frequency ratio of acentrics to dicentrics, produced in lymphocytes, on treatment with radiation, the substance and the combination of the 2 agents. The results confirm the findings of a previous experiment carried out using sodium iothalamate, showing that this ratio is markedly influenced by the relative action of the physical and the chemical agents, especially at low radiation doses, because of the enhancement of the frequency of acentrics, and not of dicentrics, caused by the presence of the drug compared to the spontaneous level.