STP1007: Experimental Freshwater Microcosm Biodegradability Study of Butyl Benzyl Phthalate

    Adams, WJ
    Science fellow, research chemist, research specialist, research technicians, and senior fellow, Monsanto Co., Environmental Sciences Center, St. Louis, MO

    Renaudette, WJ
    Science fellow, research chemist, research specialist, research technicians, and senior fellow, Monsanto Co., Environmental Sciences Center, St. Louis, MO

    Doi, JD
    Science fellow, research chemist, research specialist, research technicians, and senior fellow, Monsanto Co., Environmental Sciences Center, St. Louis, MO

    Stepro, MG
    Science fellow, research chemist, research specialist, research technicians, and senior fellow, Monsanto Co., Environmental Sciences Center, St. Louis, MO

    Tucker, MW
    Science fellow, research chemist, research specialist, research technicians, and senior fellow, Monsanto Co., Environmental Sciences Center, St. Louis, MO

    Kimerle, RA
    Science fellow, research chemist, research specialist, research technicians, and senior fellow, Monsanto Co., Environmental Sciences Center, St. Louis, MO

    Franklin, BB
    Group leader—Aquatic Toxicology, ABC Laboratories, Columbia, MO

    Nabholz, JV
    Ecologist, U.S. Environmental Protection Agency, Office of Pesticides and Toxic Substances, Health and Environmental Review Division, Washington, DC

    Pages: 22    Published: Jan 1988


    Abstract

    A 30-day freshwater microcosm study was conducted to measure the biodegradability of butyl benzyl phthalate (BBP) in water and sediment. Microcosms were designed to simulate the flow rate, water to sediment surface ratio, and environmental conditions of the Illinois River. Water and undisturbed sediment cores were brought into the laboratory from the Illinois River and placed in 53-L all-glass microcosms. BBP was tested at 10 and 100 μg/L and at 100 μg/L sterilized with five replicates at each concentration. BBP was added to each microcosm three times per week at one half the initial dose. The microcosms were sealed to trap radiolabeled carbon dioxide (14C-CO2) for purposes of assessing mineralization and obtaining a mass balance on each microcosm. Uniformly ring-labeled 14C-BBP was used as the test material and analyses were performed for parent BBP as well as for carbon-14 (14C) intermediates.

    The results of this study indicated that BBP was readily degraded in both water and sediment. The estimated half-life in water for primary degradation was typically two days or less. Mineralization of BBP did occur, with an average of 10.4% of the total BBP dosed in each microcosm trapped as 14CO2. Concentrations of BBP on the sediments were lower than predicted from sediment partition coefficients. (200 to 600 μg/kg) and ranged from 7 to 23 μg/kg. Both the sediment and water analyses showed that the majority of the 14C activity detected was not BBP. The transient appearance of primary metabolites was observed, however, the preponderance of 14C remaining in solution was not BBP.

    A mass balance of each component (water, sediment, carbon dioxide, and so forth) in each microcosm indicated that 78.2% of the total amount of 14C-BBP added to the microcosms could be accounted for. Approximately 50% of the mass remained as 14C metabolites in the water, and only 1.8% and <0.1% were found as 14C and parent BBP, respectively, on the sediment. The remainder of the 14C-BBP was found on the glass, in silicone joints and stoppers, in evolved CO2, or was removed by water sampling.

    The collective data indicate that BBP should not be a persistent chemical in freshwater aquatic environments.

    Keywords:

    microcosm, butyl benzyl phthalate, sediment biodegradation and metabolites, aquatic toxicology


    Paper ID: STP10278S

    Committee/Subcommittee: E47.01

    DOI: 10.1520/STP10278S


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