Chlorpyrifos in surface waters before and after a federally mandated ban

Samples collected from rural and urban streams in the City of Denton, Texas, USA were analyzed for the organophosphorus pesticides diazinon and chlorpyrifos during the years preceding and following a United States Environmental Protection Agency ban on many chlorpyrifos uses. A network of 70 monitor...

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Bibliographic Details
Published in:Environment international 2005-04, Vol.31 (3), p.351-356
Main Authors: Banks, Kenneth E., Hunter, David H., Wachal, David J.
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Applied sciences
Ban
Biological and medical sciences
Chlorpyrifos
Chlorpyrifos - analysis
Chlorpyrifos - economics
Commerce
Continental surface waters
Diazinon
Earth sciences
Earth, ocean, space
ELISA
Engineering and environment geology. Geothermics
Environment
Environmental Monitoring
Enzyme-Linked Immunosorbent Assay
Exact sciences and technology
Federal Government
Fundamental and applied biological sciences. Psychology
Immunoassay
Insecticides - analysis
Insecticides - economics
Natural water pollution
Pollution
Pollution, environment geology
Seasons
Soil and water pollution
Soil science
Texas
Urban watersheds
Water Movements
Water Pollutants, Chemical - analysis
Water treatment and pollution
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Summary:Samples collected from rural and urban streams in the City of Denton, Texas, USA were analyzed for the organophosphorus pesticides diazinon and chlorpyrifos during the years preceding and following a United States Environmental Protection Agency ban on many chlorpyrifos uses. A network of 70 monitoring stations, based mainly on topography and hydrological considerations, were established within the three main watersheds of Denton. Monitoring stations were sampled monthly from March through August during periods of normal flow (baseflow), resulting in a total of 308 samples and 311 samples collected during 2001 and 2002, respectively. Pesticide concentrations were determined using commercially available enzyme-linked immunosorbent assays (ELISA) specific for each pesticide. Results from this temporally and spatially dense monitoring effort were used to illustrate the impacts of a ban on most chlorpyrifos sales that was imposed in December 2001. The total number of samples exhibiting concentrations above method lower limits of detection (LLD) decreased between 2001 and 2002 for both chlorpyrifos and diazinon. The total number of sites exhibiting at least one sample with concentrations above the LLD for chlorpyrifos, however, significantly decreased (Fisher's exact test, p≪0.0001, n=70) when comparing 2001 (before the ban) with 2002 (after the ban). Similar analyses indicated no significant difference (Fisher's exact test, p=0.50, n=70) in the number of sites exhibiting detectable diazinon concentration between 2001 and 2002. Our results indicate that the cessation of retail chlorpyrifos sales at the end of 2001 resulted in a highly significant decrease in the surface water occurrences of this pesticide during 2002.
ISSN:0160-4120
1873-6750
DOI:10.1016/j.envint.2004.08.007