Quantification of FISH-painted chromosome aberrations after domestic radon exposure.

Chromosome painting (target chromosomes 1, 4, 12) was performed in peripheral lymphocytes from 25 occupants of nine houses with indoor radon concentrations of 210-3000 Bqm-3. Compared to a control group, the mean frequency of symmetrical translocations of the radon group was slightly but not significantly (p < 0.10) increased. A similar tendency became apparent for a comparison of two groups of subjects with cumulative radon exposures above and below 2800 Bqm-3 y. It is concluded that FISH-based measurements of stable symmetrical translocations should reflect the cumulative radon exposure to haematopoietic compartments such as the red bone marrow rather than to mature blood lymphocytes. Since, however, radon-derived bone marrow doses are low and control frequencies of translocations are very high (about 10-fold higher than the value for conventionally scored dicentrics), the observed relative increase (1.5-fold) of the translocation frequency in blood lymphocytes is too small to discriminate chronic radon exposure from background.