GENOTOXIC AND MUTAGENIC EFFECTS OF THE DIAGNOSTIC USE OF TL-201 IN NUCLEAR-MEDICINE

In order to investigate possible mutagenic effects of in vivo exposure to low levels of ionizing radiation used in nuclear medicine, we have examined the hypoxanthine guanine phosphoribosyl transferase (hprt) mutant fraction (MF) and chromosome aberration (CA) frequency in 24 nuclear medicine patients before and after injection of thallium-201. The mean MF of the thallium-201-exposed cohort was 5.2 +/- 4.4 x 10(-6) before injection exposure. No significant difference in MF was observed 24 h later. In 11 patients who were studied on a third occasion, 30 days after thallium-201 exposure, there was again no significant difference in post-exposure as compared with the pre-exposure MF. The frequency of CA in peripheral blood lymphocytes was not significantly different, comparing pre- and 24 h to 1 month post-radionuclide exposure. Thus, thallium-201 exposure was not associated with significant elevations in MF or CA frequency in lymphocytes of exposed individuals.