[en] Syrian hamsters exposed to an aerosol of ⁹⁰Y in fused clay received cumulative doses to lung of 3000 to 11,000 rads. These animals developed pulmonary fibrosis characterized by an early increase of collagen synthesis which leads to collagen accumulation. Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were fed to these hamsters to evaluate the antioxidant properties of these drugs in preventing irreversible pulmonary connective tissue changes. At an early time (5 weeks after exposure) when collagen synthesis was increased but breakdown and accumulation were normal, BHA-BHT did not alter either the biochemical or the anatomical and physiological responses. At a later time (12 and 19 weeks after exposure) when breakdown and accumulation were elevated and scarring was present, oral BHA-BHT did not alter these radiation-induced responses. It appears that oral BHA-BHT has no measurable protective effect against radiation-induced pulmonary fibrosis in Syrian hamsters. (U.S.)