STP667: Uptake, Biotransformation, Disposition, and Elimination of 2-Methylnaphthalene and Naphthalene in Several Fish Species

    Melancon, MJ
    Research associate and professor of pharmacology, Medical College of Wisconsin, Milwaukee, Wis.

    Lech, JJ
    Research associate and professor of pharmacology, Medical College of Wisconsin, Milwaukee, Wis.

    Pages: 18    Published: Jan 1979


    Abstract

    The uptake, disposition, biotransformation, and elimination of 14C-2-methylnaphthalene and 14C-naphthalene have been studied in several species of fish. The half-lives of elimination of 14C from several tissues, following the exposure of rainbow trout fingerlings to both compounds for 8 h, were less than 24 h. After exposure of the trout to 14C-naphthalene for four weeks, the half-life of elimination was hundreds of hours. After exposure to 14C-2-methylnaphthalene for four weeks, the elimination of 14C was biphasic; the rapid phase of elimination had a half-life of less than 24 h while the half-life of the slow phase was hundreds of hours. Examination of the muscle 14C by thin-layer chromatography (TLC) suggested that differential elimination of the parent compound and its metabolites may be involved in these differences. The elimination of 14C from fingerling carp after four weeks of exposure to 14C-2-methylnaphthalene, was also biphasic.

    Bile 14C from rainbow trout, carp, and sheepshead which had been exposed to 14C-2-methylnaphthalene was present mainly as metabolites. Most of the metabolites appeared to be conjugated when examined by TLC.

    Greater bile 14C to water 14C ratios resulted from exposure of the fish to 14C-2-methylnaphthalene than from exposure to 14C-naphthalene and were probably related to the greater uptake of 14C-2-methylnaphthalene. This ratio was also affected by the water level of the chemical, the exposure duration, and the species of the fish.

    The disposition and biotransformation of 14C-naphthalene, 14C-2-methylnaphthalene, and 14C-1,2,4-trichlorobenzene in rainbow trout were affected by pretreatment of the trout with an inducer of microsomal enzymes, β-naphthoflavone. Biliary 14C levels were much higher in the induced trout, and the tissues contained a greater proportion of 14C as metabolites in the induced trout than in the controls.

    Keywords:

    fish, naphthalene, 2-methylnaphthalene, metabolism, induction, elimination, uptake, biotransformation, aquatic toxicology


    Paper ID: STP34874S

    Committee/Subcommittee: E35.26

    DOI: 10.1520/STP34874S


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