title: Leaching potential of some phenylureas and their main metabolites through laboratory studies.
abstract: OBJECTIVE
  Laboratory studies were conducted with the aim of defining the leaching potential of some phenylureas and their metabolites. A first study was performed for calculating their leaching index (as GUS) on the base of intrinsic properties: persistence (as DT50) and mobility (as Koc) in soil. Another study consisted of aged column leaching experiments whose meaning was to semi-quantify the occurrence of the tested compounds in the leachates, so simulating in field conditions.
  
  
  METHODS
  The tested compounds were: diuron, linuron and monolinuron (parents); 3,4-dichloroaniline (DCA), 4-chloroaniline (CLA), 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU), 1-(3,4-dichlorophenyl)urea (DCPU), 1-(4-chlorophenyl)urea (CPU) and monuron, this latter considered both as a metabolite and parent compound. The Koc values of the examined substances were determined by the HPLC screening methods, according to the OECD TG 121. DT50 determinations and aged column leaching experiments were carried out according to SETAC procedures.
  
  
  CONCLUSIONS
  The examined compounds showed a rather wide range of persistence in soil, with DT50 values less than 2 days for DCA and CLA, close to 8 days for DCPU and CPU and from 16 (diuron) up to 24.8 (DCPMU) days for the others. Their mobility was generally high, based on their Koc values, which ranged from 33 (CPU) to 406 (linuron). The GUS indices indicated that monuron has a clear potential to contaminate groundwater (> 2.8); DCPMU, monolinuron, CPU and diuron are intermediate contaminants (1.8-2.8). Linuron, DCPU, CLA and DCA exhibited a non-leaching behaviour (< 1.8). The aged leaching column experiments showed that parents were found in the leachates at very high percentages respect to the doses applied. The metabolites reached much less percentages, the highest values were observed for monuron from diuron (5.7), CPU (7.2) and DCPMU (8.2%).
  
  
  CONCLUSIONS
  Diuron, Monuron, CPU and DCPMU on the basis of their intrinsic properties, formation from their parents and occurrence in leachates from aged column leaching studies, seem to possess the characteristics of groundwater contaminants. The methodological approach of this study is relatively easy and rapid, hence it can represent a tool for a first screening of compounds such as pesticide metabolites (generally available only in small quantities and for which a field study is not conceivable) or other compounds for which not adequate environmental data are available.
authors.affiliation: Istituto Superiore di Sanità (National Institute of Health), Dipartimento Ambiente e Connessa Prevenzione Primaria, Viale Regina Elena, 299, 00161 Rome, Italy lfava@iss.it
authors.forename: Luca
authors.initials: L
authors.lastname: Fava
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Orrú
authors.forename: Daniela
authors.initials: D
authors.lastname: Businelli
authors.forename: Simona
authors.initials: S
authors.lastname: Scardala
authors.forename: Enzo
authors.initials: E
authors.lastname: Funari
mesh_terms: D006540:Herbicides / Q000032:analysis / Q000737:chemistry*; D010575:Pesticides / Q000032:analysis / Q000737:chemistry*; D010671:Phenylurea Compounds / Q000032:analysis / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D014876:Water Pollution / Q000032:analysis
chemical_list: D006540:Herbicides; D010575:Pesticides; D010671:Phenylurea Compounds; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical