Chromosome Aberrations in Uranium Miners Occupationally Exposed to 222 Radon

Cultures of peripheral blood leukocytes were examined from 15 uranium miners occupationally exposed to long-lived ${}^{222}\text{radon}$ daughters and 15 normal age-matched, nonminer male controls. Mining experience was from 1 to 28 years and estimated cumulative exposure was from 10 to 5400 work level months. Hyperdiploid cells occurred with twice the frequency in uranium miners compared to control cells (2.13 vs 1.60%). Cells with chromatid gaps, chromatid breaks and isochromatid gaps (B cells) also occurred with twice the frequency in uranium miner cells compared with control cells (12.9 vs 6.43%). The prevalence of "stable" cell aberrations such as abnormal monocentrics, deletions, and translocations was 0.0% in the controls and 0.13% in the miners. A documented indicator of radiation-induced chromosome aberration is the "unstable" cell aberration grouping. Dicentrics, rings, acentric fragments, and isochromatid breaks occurred at a frequency of 0.21% in the controls and 2.58% in the miners. All of the miners had cells with one or more of the "unstable" cell aberrations but cells of only three of the controls had this classification of chromosomal change and all of these were of the acentric fragment type. The differences between miners and controls in the prevalence of lymphocyte chromosome aberrations are statistically significant as well as of a magnitude that could be of biological importance. The findings are consistent with the conclusion that nonpulmonary cells of the miners undergo mutational changes as a consequence of exposure to radiation encountered in uranium mines.