A large segment of the population smokes cigarettes; therefore, a synergistic effect between inhaled
plutonium and cigarette smoke might influence estimatesof the health risk of plutonium and other
transuranic elements relevant to the environment. Cigarette-smoke-induced changes in pulmonary
airways of humans and laboratory animals include epithelial squamous metaplasia, with loss of cilia.
These changes may impair the mucociliary-clearance mechanism, thereby influencing the pulmonary
distribution and retention of inhaled particulate material. The overall objective of this study is to determine
whether cigarette smoking increases the probability of plutonium-induced lung cancer. Initial
experiments, designed to characterize the effect of chronic cigarette smoke exposure on pulmonary
clearance of plutonium aerosols, are described