STP921

    Use of Hexavalent Chromium as a Reference Toxicant in Aquatic Toxicity Tests

    Published: Jan 1986


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    Abstract

    The suitability of hexavalent chromium (Cr) as a reference toxicant was examined in 39 toxicity tests using six species of aquatic organisms. In 19 tests conducted during a one and one-half year period with Daphnia pulex from a laboratory culture, the mean 48-h EC50 was 0.129 mg Cr/L, with a range of 0.07 to 0.19 mg/L. The least sensitive animal tested was Lepomis macrochirus, with a mean 96-h LC50 of 191.9 mg Cr/L. Daphnia pulex was the most sensitive species followed by the saltwater species, Mysidopsis bahia and Cyprinodon variegatus. Slopes of chromium concentration versus mortality ranged from 357 for D. pulex to 0.3 for L. macrochirus, while Pimephales promelas, C. variegatus, and Gasterosteus aculeatus had similar 96-h LC50s (23.2 to 42.6 mg Cr/L) and similar concentration-mortality plot slopes (0.9 to 1.1).

    Comparing the health of the D. pulex population through time by the EC50 values revealed that while the organisms may exhibit similar EC50 values and a low coefficient of variation (CV) of 26%, concentration-mortality curve slopes varied between 285 and 422. This suggests that slopes of the concentration-mortality curves with the same EC50 values can serve as a sensitive measure of organism health through time. As a reference toxicant, hexavalent chromium provides a useful benchmark for assessing the health of toxicity test organisms through time.

    Keywords:

    reference toxicant, hexavalent chromium, Daphnia pulex, Mysidopsis bahia, Cyprinodon variegatus, Pimephales promelas, Gasterosteus aculeatus, Lepomis macrochirus, static toxicity tests, aquatic toxicology


    Author Information:

    Jop, KM
    Research associate, associate director and associate professor, and director and professor, North Texas State University, Denton, TX

    Rodgers, JH
    Research associate, associate director and associate professor, and director and professor, North Texas State University, Denton, TX

    Dorn, PB
    Senior research environmental toxicologist, Shell Development Company, Houston, TX

    Dickson, KL
    Research associate, associate director and associate professor, and director and professor, North Texas State University, Denton, TX


    Paper ID: STP29041S

    Committee/Subcommittee: E47.10

    DOI: 10.1520/STP29041S


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