For single doses of 1 5-MeV fast neutrons, the relative biological effectiveness values range from 4 to 12, except in the haematopoietic system for which the values are 2 3. For individual cells also, neutron energy is an important factor in the stochastic effectiveness of neutrons. This may be critical in maintenance of the integrity of a tissue. Cells from patients with ataxia telangiectasia are hypersensitive to cell killing and to induction of micronuclei by fast neutrons, although the degree of hypersensitivity is less pronounced than for sparsely ionizing radiation. The spectrum of DNA damage from neutrons includes clustered damage of substantial complexity and consequently reduced repairability.
Neutrons are very efficient at inducing transformation in rodent and human cellular systems.
In the former study, there was also an increase in the frequency of numerical aberrations. Within the limits of the studies, the effect was found to be dose-dependent. Fission neutrons have been shown to induce germ-line mutations in mice, including visible dominant mutations, dominant lethal mutations, visible recessive mutations and specific locus mutations. When compared with sparsely ionizing radiation on the basis of absorbed dose, fission neutrons are many-fold more effective. Neutrons have been shown to induce Hprt mutations in splenic lymphocytes of mice.