STP766: Comparison of the Toxicities of Biphenyl, Monochlorobiphenyl, and 2,2′,4,4′-Tetrachlorobiphenyl to Fish and Daphnids

    Dill, DC
    Research biologist and project leaders, Environmental Sciences Research, Dow Chemical Co., Midland, Mich.

    Mayes, MA
    Research biologist and project leaders, Environmental Sciences Research, Dow Chemical Co., Midland, Mich.

    Mendoza, CG
    Research biologist and project leaders, Environmental Sciences Research, Dow Chemical Co., Midland, Mich.

    Boggs, GU
    Research biologist and project leaders, Environmental Sciences Research, Dow Chemical Co., Midland, Mich.

    Emmitte, JA
    Senior environmental biologist, Environmental Services, Dow Chemical Co., Freeport, Tex.

    Pages: 12    Published: Jan 1982


    Abstract

    The static acute toxicities of biphenyl, 2-,3-, and 4-monochlorobiphenyl, and 2,2′,4,4′-tetrachlorobiphenyl(2,2′,4,4′-TCB) were determined for three freshwater fish species—bluegill (Lepomis macrochirus Rafinesque), rainbow trout (Salmo gairdneri Richardson) and fathead minnow (Pimephales promelas Rafinesque); one salt-water fish species—sheepshead minnow (Cyprinodon variegatus Lacepede); and one freshwater invertebrate—Daphnia magna Straus. The flow-through toxicities of 2-monochlorobiphenyl (2-MCB) and 2,2′,4,4′-TCB were determined for fathead minnows exposed for up to 32 days.

    The static acute test data showed that the toxicities of the monochlorobiphenyls were intermediate between those of biphenyl and 2,2′,4,4′-TCB. There were only slight differences in the static acute median lethal concentrations (LC50S) among the individual monochlorobiphenyl isomers for any one particular species. Daphnids and rainbow trout (Salmo gairdneri) were more sensitive to all the tested compounds than the other species.

    The flow-through 30-day LC50 values were 0.82 mg/litre (95 percent confidence interval, 0.73 to 0.94) for 2-MCB, and 0.029 mg/litre (95 percent confidence interval, 0.026 to 0.033) for 2,2′,4,4′-TCB, differing by a factor of 29-fold. In flow-through tests, exposure to both 2-MCB and 2,2′,4,4′-TCB resulted in observable toxic effects within 3 days of exposure. Melanization (body darkening) and loss of equilibrium (swimming disorientation) were the most consistently observed sublethal effects. The Day 3 median effective concentration (EC50) values for melanization were 1.36 mg/litre (95 percent confidence interval, 1.2 to 1.5) and 0.034 mg/litre (95 percent confidence interval, 0.03 to 0.039) for 2-MCB and 2,2′,4,4′-TCB, respectively. The Day 3 EC50 values for loss of equilibrium were 2.11 mg/litre (95 percent confidence interval, 1.93 to 2.37) and 0.054 mg/litre (95 percent confidence interval, 0.045 to 0.065) for 2-MCB and 2,2′,4,4′-TCB, respectively.

    A no-observed-effect concentration (the highest concentration of test chemical that killed or affected no greater percentage of test organisms than did the control treatment) was not observed for 2,2′,4,4′-TCB within the range of concentrations set in this test. After 30 days, the fish exposed to the lowest concentration of 2,2′4,4′-TCB (0.014 mg/litre) had stopped feeding, were melanized, and the majority had lost their equilibrium. The two lowest exposure concentrations (0.30 and 0.38 mg/litre) of 2-MCB did not cause mortality or morbidity greater than in the controls. These data indicate that the no-observed-effect concentration for 2-MCB is less than 0.55 mg/litre (the third lowest concentration) and equal to or greater than 0.38 mg/litre.

    Keywords:

    aquatic toxicology, fish, invertebrate, biphenyl, monochlorobiphenyl, 2,2′4,4′-tetrachlorobiphenyl, toxicity, hazard assessment


    Paper ID: STP36723S

    Committee/Subcommittee: E35.14

    DOI: 10.1520/STP36723S


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