Inter-laboratory comparison of cytogenetic endpoints for the biomonitoring of radiological workers.

PURPOSE: The evaluation of different cytogenetic endpoints of radiation damage for the biomonitoring of contract workers temporarily employed at nuclear power plants. MATERIALS AND METHODS: Blood samples from six donors were irradiated in vitro with doses ranging from 0.1 to 2Gy 60Co gamma-rays. Compared were a conventional analysis for dicentrics, the conventional micronucleus (MN) assay, the centromere micronucleus assay using p82H and an alphaAllCen pancentromeric probe, and tricolour FISH with chromosome 2, 4 and 8 DNA probes for the scoring of translocations. RESULTS: Agreement in the number of MN between Giemsa-and propidium iodine fluorescence-stained preparations was obtained. The control samples showed higher centromere positivity for the MN after FISH with the p82H probe compared with the alphaAllCen probe. The MN results with both probes showed a slight but systematic increase in the number of centromere-positive MN with dose, indicating that radiation, although principally clastogenic, also has aneuploidogenic properties. The values of the genomic translocation frequency (FG) derived from the observed translocation frequencies were systematically higher than the dicentric yields. Comparing the sensitivity of the different methods with restriction of the scoring time to 1 day for biomonitoring purposes, the centromere micronucleus assay had the lowest dose detection limit (0.1 to 0.2 Gy). CONCLUSION: This study shows that at present only the centromere micronucleus assay can combine high sensitivity with a reasonable scoring time for the biomonitoring of relatively large populations