The induction of chromosome aberrations in human lymphocytes by different radiations has been studied for many years. Results have been published for several qualities of radiation which include X rays, γ rays, neutrons of various energies and alpha particles. For each of these the linear quadratic equation has fitted the data although for some the dose-squared coefficient is zero. This work has progressed to the use of accelerated charged particles for track segment irradiation of blood, that is, exposure within a narrow range of LET. This paper presents results produced by 8.7 MeV protons and 23 MeV helium-3 ions. A preliminary analysis based on the microdosimetric properties of the radiations compares these results with predictions made from the earlier neutron and alpha particle measurements.