Toxicity of inhaled 91Y in fused aluminosilicate particles in beagle dogs. VII

Studies of the radiation hazards due to inhalation of 91Y in fused aluminosilicate particles have been undertaken in Beagle dogs to aid in assessing the biological consequences of inhaling a relatively insoluble, energetic beta emitter with an intermediate effective half-life in the lung. A radiation dose pattern study in which 30 dogs were serially sacrificed from 0 to 320 days after inhalation exposure to 91Y in fused aluminosilicate particles has been completed and results are reported. A longevity study is in progress in which 96 dogs were exposed to achieve initial lung burdens ranging from 11 to 300 μCi 91Y in fused aluminosilicate particles/kg body weight and 12 dogs were exposed to stable yttrium in fused aluminosilicate particles. To date, 47 dogs have died in the longevity study between 113 and 1847 days after exposure. Forty-nine exposed dogs with doses to lung of 2,400 to 23,000 rads and 12 control dogs remain alive from 1833 to 2381 days after inhalation exposure and will continue to be studied throughout the remainder of their life span with attention directed toward determining the relationship between radiation dose, dose rate and biologic effects