A cytogenetic analysis of the long-term effect of uranium mining on peripheral lymphocytes using the micronucleus-centromere assay

Purpose : To assess the long-term effect of radiation exposure of uranium m iners on a cytogenetic endpoint: micronuclei (Mn) with and without a centro mere. Materials and methods : Mn were scored using the cytochalasin-B technique. It is known that Mn can comprise acentric fragments or/and whole chromosome s. Mn containing whole chromosomes were identified by means of fluorescence in situ hybridization (FISH) with a centromere-specific probe. The frequen cy and percentage of Mn were analysed with centromeres (MnC+) in lymphocyte s of healthy donors and uranium miners with large radiation exposures sever al decades ago employed by the Wismut AG in the former German Democratic Re public. The miners were subdivided into those with and those without bronch ial carcinoma. Results: It was shown previously that the relative frequency of MnC+ decrea sed with dose; this means that the number of Mn originating from acentric f ragments increases. In the study presented here, no statistically significa nt difference in the overall Mn frequency was seen between the analysed gro ups. The fraction of MnC+, however, was highest in lymphocytes of healthy m ale donors (mean: 74.6%) followed by healthy miners (mean: 62.1%) and those suffering from cancer (mean: 55.8%). Conclusion : The results indicate the occurrence of a genomic instability i n lymphocytes of miners, especially those with cancer. It appears that the low percentage of MnC+ may be a marker of genomic instability and cancer pr edisposition.