INDUCTION OF MICRONUCLEI IN RESPIRATORY-TRACT FOLLOWING RADON INHALATION

Male Wistar rats were exposed to radon and its progeny (0.0, 60, 262 a nd 564 working level months, WLM), and the frequency of micronuclei wa s determined in deep lung fibroblasts, and deep lung, trachea and nasa l epithelial cells with slopes of 0.28, 0.67, 0.34 and 0.11 micronucle i/1000 binucleated cells/WLM respectively. Micronuclei in deep lung fi broblasts, isolated and cultured using two methods and media, demonstr ated no differences in slopes. Biological damage was used as a biodosi meter to calculate the relationship between dosimetric units: alpha pa rticle traversals or 'nuclear hits', dose in mGy and exposure in WLM. The estimated number of nuclear alpha traversals/Gy was 6.3. Radon exp osure to 170 WLM resulted in the same frequency of micronuclei in deep lung epithelial cells as produced by one alpha hit/cell nucleus. Abso rbed dose/unit of exposure (mGy/WLM) was estimated assuming the damage was related to absorbed dose or to changes in cell sensitivity and ra nged from 1.13 to 1.34 for deep lung epithelial cells, 0.47 to 1.09 fo r deep lung fibroblasts, 0.34 to 0.67 for tracheal epithelial cells an d 0.18 to 0.33 for nasal epithelial cells. Biological dosimetry can be used to relate exposure to damage, compare dosimetric units and valid ate physical dosimetry models. This approach can be applied to any inh aled material capable of producing biological damage.