STP802

    Resolving Some Practical Questions About Daphnia Acute Toxicity Tests

    Published: Jan 1983


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    Abstract

    Acute toxicity tests were performed with six age groups of Daphnia magna, ranging from ≤6 h to 216 h, and with five chemicals, selected on the basis of their physical and chemical properties as well as their acute toxicity to D. magna. The age of the daphnids did not significantly alter the 48-h EC50 values for the chemicals tested. The maximum difference observed in the 48-h EC50 values between the 6-h and 216-h age groups was a factor of 3.9 for linear alkylbenzene sulfonate (LAS). For purposes of standardization, it appears that D. magna up to 48 h of age at the beginning of the test can be used to conduct acute toxicity tests with most chemicals.

    The results of static acute toxicity tests conducted with butylbenzyl phthalate (BBP) and D. magna in the presence and absence of several commonly used solvents indicate that the acute toxicity of this chemical is not altered by the use of a solvent carrier. The 48-h EC50 value for BBP without a solvent was 1.0 mg/L, compared with a range of 1.6 to 2.2 mg/L when acetone, dimethylformamide, ethanol, or triethylene glycol were used as solvent carriers. The acute toxicities of the solvents in the absence of BBP were also determined for D. magna. The values ranged from 9.3 to 52.4 g/L.

    The results of static acute tests performed with D. magna and BBP in the presence of various concentrations of daphnid foods (algae or trout chow), indicate that the 48-h EC50 values increase proportionally with an increase in food concentrations. These results suggest that acute toxicity tests with D. magna should be conducted in the presence of food with chemicals with a high Koc if the results are to be used to select the test concentrations for a chronic study with daphnids. The type of food and the concentration used in the acute test should be the same as those used in a chronic test.

    Keywords:

    Daphnia magna, acute toxicity, EC, 50, butylbenzyl phthalate, age sensitivity, food interactions, solvent interactions, aquatic toxicology, hazard assessment


    Author Information:

    Barera, Y
    Student research assistant and research group leader, Monsanto Co., St. Louis, MO

    Adams, WJ
    Student research assistant and research group leader, Monsanto Co., St. Louis, MO


    Paper ID: STP33527S

    Committee/Subcommittee: E47.01

    DOI: 10.1520/STP33527S


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