title: Modeling Remobilization of Neonicotinoid Residues from Tree Foliage in Streams-A Relevant Exposure Pathway in Risk Assessment?
abstract: Systemic neonicotinoid insecticides are increasingly used as a crop protection measure to suppress insect pests on trees. However, senescent foliage falling from treated trees represents a rarely studied pathway through which neonicotinoids may enter nontarget environments, e.g., surface waters. To estimate risk posed by this pathway, neonicotinoid residues were analyzed in foliage from black alder trees treated with one of three neonicotinoid insecticides (imidacloprid, thiacloprid, or acetamiprid) at five concentrations, each ranging from 0.0375-9.6 g active ingredient/cm trunk diameter at breast height (n = 3). Foliar residues measured at the time of leaf fall were used as input parameters for a model predicting imidacloprid water concentrations over a 100-m-long stream stretch as a consequence of remobilization from introduced foliage (input: 600 g foliage/m2containing 80 μg imidacloprid/g). The water concentration (up to ∼250 ng/L) predicted by the model exceeded the recently proposed Maximum Permissible Concentration of 8.3 ng/L for ∼6.5 days. Moreover, dietary uptake was identified as an additional exposure route for aquatic organisms. The alternative pathway (i.e., introduction via leaf fall) and exposure route (i.e., dietary uptake) associated with the systemic nature of neonicotinoids should be accounted for during their registration process in order to safeguard ecosystem integrity.
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau , Fortstraße 7, D-76829 Landau, Germany.
authors.forename: Dominic
authors.identifier: 0000-0002-7973-7616
authors.initials: D
authors.lastname: Englert
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau , Fortstraße 7, D-76829 Landau, Germany.
authors.forename: Nikita
authors.initials: N
authors.lastname: Bakanov
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau , Fortstraße 7, D-76829 Landau, Germany.
authors.forename: Jochen P
authors.initials: JP
authors.lastname: Zubrod
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau , Fortstraße 7, D-76829 Landau, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schulz
authors.affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences , Lennart Hjelms väg 9, SWE-75007 Uppsala, Sweden.
authors.forename: Mirco
authors.initials: M
authors.lastname: Bundschuh
mesh_terms: D000818:Animals; D007093:Imidazoles / Q000737:chemistry; D007306:Insecticides; D009574:Nitro Compounds / Q000737:chemistry; D018570:Risk Assessment; D045483:Rivers; D014197:Trees / Q000378:metabolism*; D014874:Water Pollutants, Chemical
chemical_list: D007093:Imidazoles; D007306:Insecticides; D009574:Nitro Compounds; D014874:Water Pollutants, Chemical