Relative biological effectiveness of neutrons: Induction of malformations in a mouse strain with genetic predisposition

Female hybrid mice (C57BL/6J x HLG) were exposed to 0.5 Gy of cyclotron neu trons (mean energy 5.8 MeV) after mating with HLG males when embryos were a t the early zygote stage. Uterine contents were examined on gestation day 1 9 for prenatal mortality and malformed development. The results were compar ed to those obtained after irradiation of zygotes with 1.0 and 1.7 Gy X ray s. The number of malformed fetuses was greater than for the unirradiated co ntrols, Gastroschisis was the main observation, but exencephaly was also ob served, The neutron relative biological effectiveness (RBE) for the inducti on of lethal events and malformations in the [(C57BL/6J x HLG)F-1 x HLG] mi ce was estimated. This value is higher than that for the RBE calculated for the HLG strain, which is known to be more sensitive to radiation than the hybrids. (C) 2000 by Radiation Research Society.