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Are Pyrethroid Insecticides in Our Streams?

USGS scientist lifting a filter caked with sediment that's on top of a filter plate used for filtering suspended sediment from water samples.
USGS scientist lifting a filter caked with sediment that's on top of a filter plate used for filtering suspended sediment from water samples. The filter was saved for later analysis for pyrethroid insecticides in the sediment. USGS scientists have developed a method to determine the concentration of a suite of pyrethroid insecticides absorbed to sediment particles.
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U.S. Geological Survey (USGS) scientists have detected pyrethroid insecticides in stream waters in urban and agricultural areas. Highly toxic to fish and invertebrates, the occurrence of pyrethroids in aquatic environments has become an ecological health concern. Pyrethroid insecticides are increasingly being used as replacements for organophosphate insecticides. Pyrethroids are frequently applied in urban environments and can be transported into storm drains with low levels of suspended sediments. Since pyrethroids are hydrophobic compounds that tend to move out of the water phase, earlier work focused on their detections in streambed sediments. Under these circumstances, these findings showed that pyrethroids may be transported dissolved in the water (dissolved phase), making them more bioavailable to aquatic organisms.

Transport in Water

A recent article in the Journal of Agricultural and Food Chemistry described how USGS scientists measured pyrethroids in water samples collected from urban streams and drains in the greater Sacramento area in California. The water samples were split into two phases, the dissolved (dissolved in water) phase and the particulate (associated with suspended sediments) phase. The amount of pyrethroids detected that were associated with the suspended sediments (particulates) ranged from 68 to 98 percent, even though the suspended sediment concentrations were relatively low (20 to 72 milligrams per liter (mg/L)). Measuring the occurrence and distribution of pyrethroids in these environmental compartments provides clues to understanding their fate. Whether the pyrethroids are in the dissolved phase or associated with suspended sediments influences their transport, persistence, bioaccumulation, and toxicity. Pyrethroids that are dissolved move through the water column and degrade differently from those associated with particulates. Fewer of the water samples are expected to indicate toxicity to aquatic organisms if only the dissolved water concentration was tested rather than the whole water concentration (the sum of both phases—water and sediment). Measuring pyrethroid concentrations in each phase, rather than as whole water (both phases combined) or in just one phase, allows for greater characterization and understanding of pyrethroids in the environment.

References

Hladik, M.L., and Kuivila, K.M., 2009, Assessing the occurrence and distribution of pyrethroids in water and suspended sediments: Journal of Agricultural and Food Chemistry, v. 57, no. 19, p. 9079-9085, doi:10.1021/jf9020448.

Hladik, M.L., J.L., O., and Kuivila, K.M., 2009, Collection of pyrethroids in water and sediment matrices--Development and validation of a standard operating procedure: U.S. Geological Survey Scientific Investigations Map 2009-5012, 22 p.

Hladik, M.L., Smalling, K.L., and Kuivila, K.M., 2009, Methods of analysis--Determination of pyrethroid insecticides in water and sediment using gas chromatography/mass spectrometry: U.S. Geological Survey Techniques and Methods 5-C2, 18 p.

Hladik, M.L., Smalling, K.L., and Kuivila, K.M., 2008, A multi-residue method for the analysis of pesticides and pesticide degradates in water using HLB solid-phase extraction and gas chromatography--ion trap mass spectrometry: Bulletin of Environmental Contamination and Toxicology, v. 80, no. 2, p. 139-144, doi:10.1007/s00128-007-9332-2.

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Created on Tuesday, July 13, 2010