title: Toxicity in relation to mode of action for the nematode Caenorhabditis elegans: Acute-to-chronic ratios and quantitative structure-activity relationships.
abstract: Acute-to-chronic ratios (ACRs) and quantitative structure-activity relationships (QSARs) are of particular interest in chemical risk assessment. Previous studies focusing on the relationship between the size or variation of ACRs to substance classes and QSAR models were often based on data for standard test organisms, such as daphnids and fish. In the present study, acute and chronic toxicity tests were performed with the nematode Caenorhabditis elegans for a total of 11 chemicals covering 3 substance classes (nonpolar narcotics: 1-propanol, ethanol, methanol, 2-butoxyethanol; metals: copper, cadmium, zinc; and carbamates: methomyl, oxamyl, aldicarb, dioxacarb). The ACRs were variable, especially for the carbamates and metals, although there was a trend toward small and less variable ACRs for nonpolar narcotic substances. The octanol-water partition coefficient was a good predictor for explaining acute and chronic toxicity of nonpolar narcotic substances to C. elegans, but not for carbamates. Metal toxicity could be related to the covalent index χm2r. Overall, the results support earlier results from ACR and QSAR studies with standard freshwater test animals. As such C. elegans as a representative of small soil/sediment invertebrates would probably be protected by risk assessment strategies already in use. To increase the predictive power of ACRs and QSARs, further research should be expanded to other species and compounds and should also consider the target sites and toxicokinetics of chemicals.
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Ristau
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Yeliz
authors.initials: Y
authors.lastname: Akgül
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Anna Sophie
authors.initials: AS
authors.lastname: Bartel
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Fremming
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Marie-Theres
authors.initials: MT
authors.lastname: Müller
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Luise
authors.initials: L
authors.lastname: Reiher
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Frederike
authors.initials: F
authors.lastname: Stapela
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Jan-Paul
authors.initials: JP
authors.lastname: Splett
authors.affiliation: Department of Animal Ecology, Bielefeld University, Bielefeld, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Spann
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects*; D021281:Quantitative Structure-Activity Relationship; D012098:Reproduction / Q000187:drug effects; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical
keywords: Acute-to-chronic ratio; Assessment factor; Extrapolation; Quantitative structure-activity relationship; Risk assessment