Induction of micronuclei in a rat alveolar epithelial cell line by alpha particle irradiation

Dose-response relationships for the induction of micronuclei were characterised in the rat alveolar epithelial cell line (SV40T2) exposed to either alpha particles(241Am: 3.2 MeV, 128 keV.micron-1, 0.093 Gy.min-1 at the cell-Mylar interface) or X rays (200 kVp, 1 Gy.min-1). The frequency of micronucleus formation was 1.6-3.0% for unirradiated subjects but increased for irradiated ones in a dose-dependent manner. A linear relationship between the dose and the micronucleus formation was observed until 1 Gy for alpha particles and 4 Gy for X rays. The linear slope for alpha particles was 28.5% per Gy and the relative biological effectiveness (RBE) was 4.3, as calculated from the slopes. The slope for alpha particles was dependent on the energy of the alpha particles. These results indicate that the micronucleus assay is available for biodosimetry of alpha particle irradiation in the rat alveolar epithelial cells, although consideration should be given to the range of the linearity and the LET of alpha particles.