title: Comparison of tropical and temperate freshwater animal species' acute sensitivities to chemicals: implications for deriving safe extrapolation factors.
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.
authors.affiliation: The Swire Institute of Marine Science, Department of Ecology and Biodiversity, The University of Hong Kong, Pokfulam, Hong Kong, PR China. kmyleung@hkucc.hku.hk
authors.forename: Kevin W H
authors.initials: KW
authors.lastname: Kwok
authors.forename: Kenneth M Y
authors.initials: KM
authors.lastname: Leung
authors.forename: Gilbert S G
authors.initials: GS
authors.lastname: Lui
authors.forename: S Vincent K H
authors.initials: SV
authors.lastname: Chu
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Lam
authors.forename: David
authors.initials: D
authors.lastname: Morritt
authors.forename: Lorraine
authors.initials: L
authors.lastname: Maltby
authors.forename: Theo C M
authors.initials: TC
authors.lastname: Brock
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Van den Brink
authors.forename: Michael St J
authors.initials: MS
authors.lastname: Warne
authors.forename: Mark
authors.initials: M
authors.lastname: Crane
mesh_terms: D000818:Animals; D017753:Ecosystem; D005399:Fishes / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry*; D007448:Invertebrates / Q000187:drug effects*; D008954:Models, Biological; D011237:Predictive Value of Tests; D013045:Species Specificity; D018675:Toxicity Tests / Q000379:methods*; D014329:Tropical Climate; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical