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Scientific Investigations Report 2008-5016

Occurrence of Chlorothalonil, Its Transformation Products, and Selected Other Pesticides in Texas and Oklahoma Streams, 2003–2004

By William A. Battaglin, Kathryn Kuivila, Kim Winton, and Michael Meyer

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Scientific Investigations Report
2008-5016 PDF (1 MB)

The primary purpose of the study described in this report was to determine if the fungicide chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), three of its transformation products, or selected other pesticides are transported to surface water after use on peanuts or other crops in Texas and Oklahoma. The results summarized here are part of a larger study that includes data from sites in Alabama, Florida, and Georgia. Chlorothalonil is classified as a probable carcinogen, and the 4-hydroxy of chlorothalonil transformation product is more soluble, more stable, and, for some species, more toxic than its parent compound. In 2003, water samples were collected from three surface-water sites in Texas and two surface-water sites in Oklahoma; in 2004, samples were collected from the two Oklahoma sites. Chlorothalonil was not detected in any of the 20 samples analyzed. The 4-hydroxy of chlorothalonil transformation product was detected in three samples collected in 2004, with a maximum concentration of 0.018 microgram per liter (μg/L); the other two transformation products (diamide chlorothalonil and 1-amide-4-hydroxy chlorothalonil) were not detected in any sample. In addition, 19 samples were analyzed for as many as 109 other pesticides and transformation products. Atrazine was detected in 13 samples and had a maximum concentration of 0.122 μg/L. Deethylatrazine was detected in 10 samples and had a maximum concentration of 0.04 μg/L. Metolachlor was detected in eight samples and had a maximum concentration of 0.019 μg/L. Fifteen other pesticides or pesticide transformation products also were detected. In general, concentrations of pesticides were less than concentrations that are commonly observed in Midwestern streams. The results indicate that the use of chlorothalonil on peanut crops has not resulted in substantial contamination of the studied streams in Texas and Oklahoma.

Version 1.0

Posted April 2008

Suggested citation:

Battaglin, W.A., Kuivila, K., Winton, K., and Meyer, M., 2008, Occurrence of chlorothalonil, its transformation products, and selected other pesticides in Texas and Oklahoma streams, 2003–2004: U.S. Geological Survey Scientific Investigations Report 2008–5016, 9 p.




Chlorothalonil Use and Toxicity

Sampling Sites and Sample Collection

Analytical Methods

Occurrence of Chlorothalonil, Its Transformation Products, and Selected Other Pesticides



References Cited


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