Clastogenic Effects of Defined Numbers of 3.2 MeV Alpha Particles on Individual CHO-K1 Cells

Research to determine the effects of defined numbers of α particles on individual mammalian cells is helpful in understanding risks associated with exposure to radon. This paper reports the first biological data generated using the single-particle/single-cell irradiation system developed at Pacific Northwest Laboratory. Using this apparatus, CHO-K1 cells were exposed to controlled numbers of 3.2 MeV α particles, and biological responses of individual cells to these irradiations were quantified. Chromosomal damage, measured by the induction of micronuclei, was evaluated after no, one, two, three or five particle traversals. Exposures of up to five α particles had no influence on the total numbers of cells recovered for scoring. With increased numbers of α particles there was a decrease in the ratio of binucleated to mononucleated cells of 3.5%/hit, suggesting that α particles induced dose-dependent mitotic delay. A linear hit-response relationship was observed for micronucleus induction: Micronuclei/binucl...