Abstract: Objective To study the toxicity of polyethylene dust.Methods Polyethylene dust was breathed by the rats with a passive powder breath-in method,and to toxicity of the rat's lung macrophage and the change of the rat's lung tissue were observed.Results The LD₅₀ of polyethylene dust was greater than 15 000～30 000 mg/kg,polyethylene was nonpoisonous;The pigmentingrate of the marcophage and the active units of bactute dehydrogenase were higher obviously than that of the normal group(P<0.001)in the culture media of infeted external cells,and lower than that of the quarze dust group,with slight toxicity to the rat's lung macrophage.By observing the rat's bronchus infected with dust from one to eighteen months,the hyperplasia of retioular fiber and a little collcegen fiber in the sections of the rat's tissue were seen,but the pathologic change and fibrosis of which were lower than that caused by the quarze dust.Conclusion Polythylene dust was low toxicity and fibrosis slightly to the rat's lung.