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Comparison of tropical and temperate freshwater animal species' acute sensitivities to chemicals: Implications for deriving safe extrapolation factors

Authors

  • Kevin WH Kwok,

    1. The Swire Institute of Marine Science, Department of Ecology and Biodiversity, The University of Hong Kong, Pokfulam, Hong Kong, PR China
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  • Kenneth MY Leung,

    Corresponding author
    1. The Swire Institute of Marine Science, Department of Ecology and Biodiversity, The University of Hong Kong, Pokfulam, Hong Kong, PR China
    • The Swire Institute of Marine Science, Department of Ecology and Biodiversity, The University of Hong Kong, Pokfulam, Hong Kong, PR China
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  • Gilbert SG Lui,

    1. Department of Statistics and Actuarial Sciences, The University of Hong Kong, Pokfulam, Hong Kong, PR China
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  • Vincent KH Chu,

    1. The Swire Institute of Marine Science, Department of Ecology and Biodiversity, The University of Hong Kong, Pokfulam, Hong Kong, PR China
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  • Paul KS Lam,

    1. Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, PR China
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  • David Morritt,

    1. School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 OEX, United Kingdom
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  • Lorraine Maltby,

    1. Department of Animal and Plant Sciences, The University of Sheffield, Sheffield 570 2TN, United Kingdom
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  • Theo CM Brock,

    1. Alterra Centre for Water and Climate, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands
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  • Paul J Van den Brink,

    1. Alterra Centre for Water and Climate, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands
    2. Wageningen University, Department of Aquatic Ecology and Water Quality Management, Wageningen University and Research Centre, PO Box 8080, 6700 DD Wageningen, The Netherlands
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  • Michael St J Warne,

    1. Centre for Environmental Contaminants Research, CSIRO Land and Water, PMB 2, Glen Osmond, South Australia 5064, Australia
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  • Mark Crane

    1. Watts & Crane Associates, 23 London Street, Faringdon, Oxfordshire SN7 7AG, United Kingdom
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Abstract

Toxicity data for tropical species are often lacking for ecological risk assessment. Consequently, tropical and subtropical countries use water quality criteria (WQC) derived from temperate species (e.g., United States, Canada, or Europe) to assess ecological risks in their aquatic systems, leaving an unknown margin of uncertainty. To address this issue, we use species sensitivity distributions of freshwater animal species to determine whether temperate datasets are adequately protective of tropical species assemblages for 18 chemical substances. The results indicate that the relative sensitivities of tropical and temperate species are noticeably different for some of these chemicals. For most metals, temperate species tend to be more sensitive than their tropical counterparts. However, for un-ionized ammonia, phenol, and some pesticides (e.g., chlorpyrifos), tropical species are probably more sensitive. On the basis of the results from objective comparisons of the ratio between temperate and tropical hazardous concentration values for 10% of species, or the 90% protection level, we recommend that an extrapolation factor of 10 should be applied when such surrogate temperate WQCs are used for tropical or subtropical regions and a priori knowledge on the sensitivity of tropical species is very limited or not available.

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