Non-linear relationship of cell hit and transformation probabilities in a low dose of inhaled radon progenies.
Cellular hit probabilities of alpha particles emitted by inhaled radon progenies in sensitive bronchial epithelial cell nuclei were simulated at low exposure levels to obtain useful data for the rejection or support of the linear-non-threshold (LNT) hypothesis. In this study, local distributions of deposited inhaled radon progenies in airway bifurcation models were computed at exposure conditions characteristic of homes and uranium mines. Then, maximum local deposition enhancement factors at bronchial airway bifurcations, expressed as the ratio of local to average deposition densities, were determined to characterise the inhomogeneity of deposition and to elucidate their effect on resulting hit probabilities. The results obtained suggest that in the vicinity of the carinal regions of the central airways the probability of multiple hits can be quite high, even at low average doses. Assuming a uniform distribution of activity there are practically no multiple hits and the hit probability as a function of dose exhibits a linear shape in the low dose range. The results are quite the opposite in the case of hot spots revealed by realistic deposition calculations, where practically all cells receive multiple hits and the hit probability as a function of dose is non-linear in the average dose range of 10-100 mGy.
Balásházy
Imre
I
Health and Environmental Physics Department, Hungarian Academy of Sciences KFKI Atomic Energy Research Institute, 1525 Budapest, PO Box 49, Hungary. ibalas@aeki.kfki.hu
Farkas
Arpád
A
Madas
Balázs Gergely
BG
Hofmann
Werner
W
D000280:Administration, Inhalation; D000396:Air Pollutants, Radioactive / Q000493:pharmacokinetics*; D001980:Bronchi / Q000378:metabolism*; D003198:Computer Simulation; D004781:Environmental Exposure / Q000032:analysis*; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D015233:Models, Statistical; D017711:Nonlinear Dynamics; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D017687:Radon Daughters / Q000493:pharmacokinetics*; D012062:Relative Biological Effectiveness; D014018:Tissue Distribution
D000396:Air Pollutants, Radioactive; D017687:Radon Daughters