The Relative Potency of Fast Neutrons and 250-Kvp X-Rays in the Guinea Pig

Abstract

The 30-day lethality response in Hartley strain guinea pigs was determined for fast neutrons and 250 kvp x rays. The LD 50/30 for animals exposed to neutrons was 155 rads, while for animals exposed to x rays it was 273 rads. Most deaths occurred 9-16 days after irradiation, and no deaths occurred before day 7 post-irradiation with either neutrons or x rays. Morphological examination indicated no marked gastrointestinal damage in the guinea pig following either neutron or x-ray exposure in the lethal range. The niost frequent finding at autopsy was hemorrhage. Only minimal gastrointestinal damage was seen following supi alethal exposures of neutrons or x rays. Body weight, food consumption, and water consumption were also determined for 30 days following irradiation. The relative potency of neutrons with respect to x rays was greater than unity for depressions in the three measurements. Food and water consumption values of survivors returned to control values by 30-days post- irradiation. Body weight, however, remained less than controls for at least 30 days in a dose dependent fashion. The gastrointestinal syndrome was essentially absent in the guinea pig followlng irradiation. lt is suggested that the greater potency of neutrons for lethality in the guinea pigmore » may be explicable on the basis of radiation damage to the hematopoietic system. (auth)« less