Studies of the effects of inhaled radionuclides help to determine protective measures to safeguard workers in atomic installations and industry. In the research shown here, the air inhaled by this group of beagles for a measured time had a small amount of an aerosol containing radioactive plutonium dioxide. Then the animals were examined over a period of up to five years to ascertain whether tissue damage had resulted. The study showed that the body excretes all but the largest particles of the radioactive material. Pacific Northwest Laboratory, circa 1970s.