title: The influence of particles on bioavailability and toxicity of pesticides in surface water.
abstract: Environmental risk assessment is an essential part of the approval process for pesticides. Exposure concentrations are compared with ecotoxicological data obtained from standardized laboratory studies and, if available, from field studies to determine the risk of a substance or formulation for aquatic communities. Predicted concentrations in surface waters are derived using, for example, the European FOrum for the Co-ordination of pesticide fate models and their USe (FOCUS) or the German Exposit models, which distinguish between exposure to dissolved and particle-associated pesticide concentrations, because the dissolved concentration is thought to be the best predictor of bioavailability and toxicity. Water and particle-associated concentrations are estimated based on the organic carbon-water partitioning coefficient (KOC). This review summarizes published information on the influence of natural suspended solids on bioavailability and toxicity of pesticides to aquatic organisms (algae, invertebrates and fish), and the value of log KOCand log KOW(octanol-water coefficient) as sole predictors of the bioavailable fraction is discussed. The information showed that: 1) the quality and origin of suspended solids played an important role in influencing pesticide bioavailability and toxicity; 2) a decrease in toxicity due to the presence of suspended solids was shown only for pyrethroid insecticides with log KOWgreater than 5, but the extent of this reduction depended on particle concentration and size, and potentially also on the ecotoxicological endpoint; 3) for pesticides with a log KOWless than 3 (e.g., triazines, carbamates, and organophosphates), the impact of particles on bioavailability and toxicity is small and species dependent; and 4) pesticide bioavailability is greatly influenced by the test species and their physiology (e.g., feeding behavior or digestion). We conclude that exposure of aquatic organisms to pesticides and environmental risk of many pesticides might be underestimated in prospective risk assessment, when predicted environmental concentration is estimated based on the KOCof a compound. Integr Environ Assess Manag 2017;13:585-600. © 2016 SETAC.
authors.affiliation: Federal Office for Agriculture, Bern, Switzerland.
authors.forename: Katja
authors.initials: K
authors.lastname: Knauer
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Dübendorf, Switzerland.
authors.forename: Nadzeya
authors.initials: N
authors.lastname: Homazava
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Dübendorf, Switzerland.
authors.forename: Marion
authors.initials: M
authors.lastname: Junghans
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Dübendorf, Switzerland.
authors.forename: Inge
authors.initials: I
authors.lastname: Werner
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D054750:Ecotoxicology; D004784:Environmental Monitoring; D007448:Invertebrates; D008962:Models, Theoretical; D010575:Pesticides / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Models; Pesticides; Protection; Regulation; Risk assessment