Meta-analysis of increases in micronuclei in peripheral blood lymphocytes after angiography or excretory urography

Meta-analysis of 10 studies confirms a significant increase in the frequenc y of micronuclei in peripheral blood lymphocytes after angiography or excre tory urography; the weighted average increase is 4.2 (95% confidence interv al 2.8-5.6) per 1000 binucleate lymphocytes? about the same increase in mic ronuclei as that produced in vitro by a diagnostic X-ray dose of 4 cGy. The analysis failed to reveal a significant effect of the specific contrast me dium used in the S-ray examinations on the increased frequency of micronucl ei, These results are consistent with the hypothesis that the effect of the contrast media is limited to the enhancement, by the photoelectric effect, of the X-ray dose absorbed bg the lymphocytes irradiated while suspended i n the contrast medium. Therefore, an estimate of increased cancer risk base d on elevated frequencies of micronuclei or chromosome aberrations in perip heral blood lymphocytes may be greatly exaggerated whenever the radiation d amage is largely confined to the cells circulating in the blood, as it is i n people who have recently had X-ray examinations that use Intravenous inje ctions oi; contrast medium. Such examinations include angiography, excretor y urography and CT scans, which are received annually by millions of people . (C) 2001 by Radiation Research Society.