title: The acetochlor registration partnership surface water monitoring program for four corn herbicides.
abstract: A surface drinking water monitoring program for four corn (Zea mays L.) herbicides was conducted during 1995-2001. Stratified random sampling was used to select 175 community water systems (CWSs) within a 12-state area, with an emphasis on the most vulnerable sites, based on corn intensity and watershed size. Finished drinking water was monitored at all sites, and raw water was monitored at many sites using activated carbon, which was shown capable of removing herbicides and their degradates from drinking water. Samples were collected biweekly from mid-March through the end of August, and twice during the off-season. The analytical method had a detection limit of 0.05 microg L(-1) for alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)-acetamide] and 0.03 microg L(-1) for acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide], atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide]. Of the 16528 drinking water samples analyzed, acetochlor, alachlor, atrazine, and metolachlor were detected in 19, 7, 87, and 53% of the samples, respectively. During 1999-2001, samples were also analyzed for the presence of six major degradates of the chloroacetanilide herbicides, which were detected more frequently than their parent compounds, despite having higher detection limits of 0.1 to 0.2 microg L(-1). Overall detection frequencies were correlated with product use and environmental fate characteristics. Reservoirs were particularly vulnerable to atrazine, which exceeded its 3 microg L(-1) maximum contaminant level at 25 such sites during 1995-1999. Acetochlor annualized mean concentrations (AMCs) did not exceed its mitigation trigger (2 microg L(-1)) at any site, and comparisons of observed levels with standard measures of human and ecological hazards indicate that it poses no significant risk to human health or the environment.
authors.affiliation: Monsanto Company, 800 North Lindbergh Boulevard, St. Louis, MO 63167, USA.
authors.forename: Amy G
authors.initials: AG
authors.lastname: Hackett
authors.forename: David I
authors.initials: DI
authors.lastname: Gustafson
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Moran
authors.forename: Paul
authors.initials: P
authors.lastname: Hendley
authors.forename: Ian
authors.initials: I
authors.lastname: van Wesenbeeck
authors.forename: Nick D
authors.initials: ND
authors.lastname: Simmons
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Klein
authors.forename: Joel M
authors.initials: JM
authors.lastname: Kronenberg
authors.forename: John D
authors.initials: JD
authors.lastname: Fuhrman
authors.forename: Joy L
authors.initials: JL
authors.lastname: Honegger
authors.forename: John
authors.initials: J
authors.lastname: Hanzas
authors.forename: David
authors.initials: D
authors.lastname: Healy
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Stone
mesh_terms: D000383:Agriculture; D004784:Environmental Monitoring; D006540:Herbicides / Q000032:analysis*; D018570:Risk Assessment; D014481:United States; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply; D003313:Zea mays
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical