title: Ranking of agricultural pesticides in the Rhine-Meuse-Scheldt basin based on toxic pressure in marine ecosystems.
abstract: Although risk assessments on a per-chemical basis are required during the registration procedure of pesticides, cumulative risks from the use of all pesticides on the variety of crops in a catchment area of a river are not assessed. The present study aimed to rank pesticides used in outdoor agricultural practice within the catchment of the rivers Rhine, Meuse, and Scheldt according to their potential toxic impact on the North Sea coastal ecosystem. Toxic pressure calculations (based on steady-state concentrations calculated with a multimedia fate model) and species-sensitivity distribution-based risk estimations were performed for pesticide emissions in the years 1998 (189 pesticides) and 2004 (133 pesticides). A ranking was established according to the relative contribution of single pesticides and crop types to the overall toxic pressure. Calculations were performed probabilistically to deal with parameter uncertainties. Only a few pesticides and crop types dominate overall toxic pressure because of emissions in both years, and the uncertainty appears to be caused largely by uncertainties in interspecies variances of aquatic toxicities. For 1998, these pesticides were fentin-acetate, with a median relative contribution (RCx) to the toxic pressure of multiple chemicals on an ecosystem of 0.43. For 2004, the pesticides that contributed most were pencycuron and paraquat-dichloride, with a median RCx, of 4.4 x 10(-2) and 3.9 x 10(-2), respectively. Pesticides applied to potato cropland and fruit trees contributed most to the overall toxic pressure.
authors.affiliation: Department of Environmental Science, Radboud University Nijmegen, Nijmegen, The Netherlands. i.henning@science.ru.nl
authors.forename: Irmgard
authors.initials: I
authors.lastname: Henning-de Jong
authors.forename: Rosalie
authors.initials: R
authors.lastname: van Zelm
authors.forename: Mark A J
authors.initials: MA
authors.lastname: Huijbregts
authors.forename: Dick
authors.initials: D
authors.lastname: de Zwart
authors.forename: Ton M A
authors.initials: TM
authors.lastname: van der Linden
authors.forename: Arjen
authors.initials: A
authors.lastname: Wintersen
authors.forename: Leo
authors.initials: L
authors.lastname: Posthuma
authors.forename: Dik
authors.initials: D
authors.lastname: van de Meent
mesh_terms: D000383:Agriculture; D017753:Ecosystem; D005060:Europe; D009792:Oceans and Seas; D010575:Pesticides / Q000145:classification / Q000633:toxicity*; D045483:Rivers
chemical_list: D010575:Pesticides