The effects of a 0-12-hour naphthalene exposure on pulmonary CO(2) excretion and bioaccumulation in the leopard frog, Rana pipiens, were investigated. The data showed that naphthalene transport occurred from the aqueous phase into the frog tissue. The first-order rate constant (k in day-1) for the entry of naphthalene from the water into the frog was 0.079 +/- 0.007 (k +/- 95% C.I.). Bioaccumulation of naphthalene was measured in liver, lung, and thigh muscle tissue. Exposure to naphthalene caused a significant reduction in pulmonary CO(2) excretion, particularly following the first 30 minutes of exposure. Pulmonary CO(2) excretion returned to baseline levels after 8 hours of exposure, indicating that some degree of acclimation had occurred. Depuration experiments were used to monitor recovery from naphthalene exposure. Recovery of CO(2) excretion was evident following 2 hours of depuration and complete elimination of naphthalene from tissues occurred after 3 hours. The data indicate that accumulated polycyclic aromatic hydrocarbons (PAHs) may alter normal physiologic functions such as gas exchange. Since amphibians, such as frogs, are one of the first organisms to come into contact with contaminated water and sediments, the information in this study suggests that this species may be used to assess bioaccumulation and toxicity of PAHs in ecosystems.