BIOLOGICAL EFFECTIVENESS OF RADON-PROGENY ALPHA-PARTICLES .2. ONCOGENIC TRANSFORMATION AS A FUNCTION OF LINEAR-ENERGY-TRANSFER

Epidemiological studies have established an association between exposu re to radon and carcinoma of the lung. However, based on data for eith er lung cancer in uranium miners exposed to radon or bronchial epithel ial carcinomas in Japanese A-bomb survivors, it has not been possible to assign estimates of risk of lung cancer for the general population exposed to radon in their homes. Based on past success with the excell ent quantitative properties of the C3H 10T1/2 in vitro oncogenic trans formation assay system, the relative biological effectiveness (RBE) fo r radiation-induced transformation for charged particles of defined LE T has been determined. As the LET of the radiation was increased, the rate of induction of oncogenic transformation increased and the RBE(m) approached 20, At higher LETs, RBE dropped precipitously. The rapid d rop in effectiveness for alpha particles with LETs between 120 and 265 keV/mu m implies a lower quality factor than the 20-25 currently cons idered appropriate when estimating lung cancer mortality. (C) 1995 by Radiation Research Society