Late cataractogenesis caused by particulate radiations and photons in long-lived mammalian species.

Radiation cataractogenesis induced by small acute doses of particulate radiations and photons in the New Zealand white (NZW) rabbit (Oryctolagus cuniculus), the beagle dog (Canis familiaris) and the rhesus monkey (Macaca mulatta) is discussed in the context of the use of animal models to assess the radiation hazards faced by humans during lengthy sojourns in deep space. Attention is paid to: 1) the importance of lifespan studies with long-lived species--the above animals have median lifespans in captivity of 5-7, 13-14 and approximately 25 years, respectively; 2) the magnitudes of possible dose thresholds for cataractogenesis from sparsely ionizing radiations and the modifications of those thresholds by the late degenerative phase of the phenomenon.