The purpose of this study is to evaluate halogenated biphenyls and naphthalenes with regard to: (1) classification of the administered agent as a dibenzo-dioxin or phenobarbital inducer; (2) compare the dose-response of induction of various isomers; (3) relate potency to tissue levels and toxicity. BIBLIOGRAPHIC REFERENCES: Goldstein, J.A., Hickman, P., Bergman, H., McKinney, J.D., and Walker, M.P.: Separation of Polychlorinated Biphenyl (PCB) Isomers into two Distinct Types of Inducers of Drug-Metabolizing Enzymes. Fed. Proc. 36: 941, 1977. Goldstein, J.A., Hickman, P., Bergman, J., McKinney, J.D. and Walker, M.P.: Separation of Pure Polychlorinated Biphenyl Isomers into Two Types of Inducers on the Basis of Induction of Cytochrome P-450 or P-448. Chem.- Biol. Interact. 17: 69-87, 1977.