New Sediment-Toxicity Benchmarks Available for Pesticides in Whole Sediment Completed
Scientists Collecting Bed-Sediment Samples from Suwanee Creek, Georgia
U.S. Geological Survey (USGS) scientists developed 129 sediment-toxicity benchmarks for use in evaluating currently used pesticides in whole sediment.
Tools such as sediment benchmarks are needed to evaluate the likelihood that pesticides detected in stream sediments may adversely affect stream invertebrate communities. Some pesticides used today in agricultural and urban applications are "hydrophobic" (that is, have low water solubility and tend to bind to particles). Such pesticides may enter streams in surface runoff and with eroded soil, and accumulate in bed sediments. Some hydrophobic insecticides (for example, pyrethroids and fipronil) that are toxic to invertebrates in laboratory tests have been detected in bed sediments of streams in agricultural and urban areas across the United States.
Sediment-toxicity benchmarks were determined for 129 pesticides based on an analysis of compiled literature and database information on laboratory toxicity tests—either spiked-sediment bioassays (preferred) or water toxicity tests (used along with equilibrium partitioning theory if sediment data were not available). Two types of freshwater whole-sediment benchmarks were developed for each pesticide:
- Likely Effect Benchmark — a concentration above which there is a high likelihood of adverse effects on benthic invertebrates, and
- Threshold Effect Benchmark — a concentration below which adverse effects are unlikely.
These benchmarks can be used to
- interpret which pesticides in a mixture are expected to contribute to observed sediment toxicity; or
- predict the potential toxicity of pesticides detected in whole sediment in monitoring studies that did not measure toxicity.
In a test to see how well these benchmarks predicted toxicity in field-collected sediments, the new benchmarks were applied to data from two case studies that collected sediment samples from a total of 197 streams across the United States. These case studies measured concentrations of pesticides in whole sediment, and also conducted laboratory whole-sediment-toxicity tests with invertebrates (amphipods and midge) using the same sediments.
In these case studies, the new benchmarks predicted toxicity to amphipods quite well. Toxicity to amphipods occurred in 100 percent of the few (three) samples that exceeded the Likely Effect Benchmark for one or more pesticides, and in 72 percent of samples that were above one or more Threshold Effect Benchmarks. In contrast, there was relatively lower (18 percent) toxicity in samples with pesticide concentrations below all benchmarks. None of the sediment benchmarks were effective in predicting toxicity or non-toxicity to midges, possibly because midges are less sensitive than amphipods or because of insufficient toxicity data for midges.
Factors affecting toxicity when sediment concentrations are below benchmarks may include the presence of other contaminants besides the pesticides being measured and physical or chemical characteristics of sediment that affect pesticide bioavailability or toxicity.
Although there is uncertainty in the benchmark values because of the scarcity of spiked-sediment bioassay data available for many pesticides, the new toxicity-based sediment benchmarks utilize the best available approaches for evaluating pesticides in whole sediments, and they can be used to assess the biological significance of pesticide concentrations measured in whole-sediment monitoring studies.
This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) and the USGS National Water-Quality Assessment (NAWQA) Project of the National Water Quality Program.
Below are other science projects associated with this project.
National Water-Quality Assessment (NAWQA)
Below are publications associated with this project.
Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides
Contaminants in stream sediments from seven United States metropolitan areas: part I: distribution in relation to urbanization
Contaminants in stream sediments from seven United States metropolitan areas: part II—sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus
The Midwest Stream Quality Assessment
Contaminants in stream sediments from seven U.S. metropolitan areas: Data summary of a National Pilot Study
Below are data or web applications associated with this project.
Regional Stream Quality Assessment (RSQA)
The Regional Stream Quality Assessment (RSQA), part of the National Water Quality Assessment project, seeks to characterize multiple water-quality factors that are stressors to aquatic life (contaminants, nutrients, sediment, and streamflow alteration) and to develop a better understanding of the relation of these stressors to ecological conditions in streams throughout the region.
- Overview
U.S. Geological Survey (USGS) scientists developed 129 sediment-toxicity benchmarks for use in evaluating currently used pesticides in whole sediment.
Tools such as sediment benchmarks are needed to evaluate the likelihood that pesticides detected in stream sediments may adversely affect stream invertebrate communities. Some pesticides used today in agricultural and urban applications are "hydrophobic" (that is, have low water solubility and tend to bind to particles). Such pesticides may enter streams in surface runoff and with eroded soil, and accumulate in bed sediments. Some hydrophobic insecticides (for example, pyrethroids and fipronil) that are toxic to invertebrates in laboratory tests have been detected in bed sediments of streams in agricultural and urban areas across the United States.
Sediment-toxicity benchmarks were determined for 129 pesticides based on an analysis of compiled literature and database information on laboratory toxicity tests—either spiked-sediment bioassays (preferred) or water toxicity tests (used along with equilibrium partitioning theory if sediment data were not available). Two types of freshwater whole-sediment benchmarks were developed for each pesticide:
- Likely Effect Benchmark — a concentration above which there is a high likelihood of adverse effects on benthic invertebrates, and
- Threshold Effect Benchmark — a concentration below which adverse effects are unlikely.
These benchmarks can be used to
- interpret which pesticides in a mixture are expected to contribute to observed sediment toxicity; or
- predict the potential toxicity of pesticides detected in whole sediment in monitoring studies that did not measure toxicity.
In a test to see how well these benchmarks predicted toxicity in field-collected sediments, the new benchmarks were applied to data from two case studies that collected sediment samples from a total of 197 streams across the United States. These case studies measured concentrations of pesticides in whole sediment, and also conducted laboratory whole-sediment-toxicity tests with invertebrates (amphipods and midge) using the same sediments.
In these case studies, the new benchmarks predicted toxicity to amphipods quite well. Toxicity to amphipods occurred in 100 percent of the few (three) samples that exceeded the Likely Effect Benchmark for one or more pesticides, and in 72 percent of samples that were above one or more Threshold Effect Benchmarks. In contrast, there was relatively lower (18 percent) toxicity in samples with pesticide concentrations below all benchmarks. None of the sediment benchmarks were effective in predicting toxicity or non-toxicity to midges, possibly because midges are less sensitive than amphipods or because of insufficient toxicity data for midges.
Factors affecting toxicity when sediment concentrations are below benchmarks may include the presence of other contaminants besides the pesticides being measured and physical or chemical characteristics of sediment that affect pesticide bioavailability or toxicity.
Although there is uncertainty in the benchmark values because of the scarcity of spiked-sediment bioassay data available for many pesticides, the new toxicity-based sediment benchmarks utilize the best available approaches for evaluating pesticides in whole sediments, and they can be used to assess the biological significance of pesticide concentrations measured in whole-sediment monitoring studies.
This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) and the USGS National Water-Quality Assessment (NAWQA) Project of the National Water Quality Program.
- Science
Below are other science projects associated with this project.
National Water-Quality Assessment (NAWQA)
Our surface water, groundwater, and aquatic ecosystems are priceless resources, used by people across the Nation for drinking, irrigation, industry, and recreation. The National Water-Quality Assessment (NAWQA) Project is a leading source of scientific data and knowledge for development of science-based policies and management strategies to improve and protect our water resources. - Publications
Below are publications associated with this project.
Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides
Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in wholeAuthorsLisa H. Nowell, Julia E. Norman, Christopher G. Ingersoll, Patrick W. MoranContaminants in stream sediments from seven United States metropolitan areas: part I: distribution in relation to urbanization
Organic contaminants and trace elements were measured in bed sediments collected from streams in seven metropolitan study areas across the United States to assess concentrations in relation to urbanization. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, the pyrethroid insecticide bifenthrin, and several trace elements were significantly related to urbanizatAuthorsLisa H. Nowell, Patrick W. Moran, Robert J. Gilliom, Daniel L. Calhoun, Christopher G. Ingersoll, Nile E. Kemble, Kathryn Kuivila, Patrick J. PhillipsContaminants in stream sediments from seven United States metropolitan areas: part II—sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus
Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toAuthorsNile E. Kemble, Douglas K. Hardesty, Christopher G. Ingersoll, James L. Kunz, Paul K. Sibley, Daniel L. Calhoun, Robert J. Gilliom, Kathryn Kuivila, Lisa H. Nowell, Patrick W. MoranThe Midwest Stream Quality Assessment
In 2013, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) and USGS Columbia Environmental Research Center (CERC) will be collaborating with the U.S. Environmental Protection Agency (EPA) National Rivers and Streams Assessment (NRSA) to assess stream quality across the Midwestern United States. The sites selected for this study are a subset of the larger NRSA, impAuthorsPeter C. Van Metre, Jeffrey W. Frey, Ellen TarquinioContaminants in stream sediments from seven U.S. metropolitan areas: Data summary of a National Pilot Study
This report presents data collected as a part of a synoptic survey of stream sediment contaminants, associated watershed characteristics and invertebrate responses in laboratory sediment toxicity tests from 98 streams (sites) in seven metropolitan study areas across the continental United States. The report presents methods, data, and sediment-quality guidelines, including the derivation of a newAuthorsPatrick W. Moran, Dan L. Calhoun, Lisa H. Nowell, Nile E. Kemble, Chris G. Ingersoll, Michelle Hladik, Kathryn Kuivila, James A. Falcone, Robert J. Gilliom - Web Tools
Below are data or web applications associated with this project.
Regional Stream Quality Assessment (RSQA)
The Regional Stream Quality Assessment (RSQA), part of the National Water Quality Assessment project, seeks to characterize multiple water-quality factors that are stressors to aquatic life (contaminants, nutrients, sediment, and streamflow alteration) and to develop a better understanding of the relation of these stressors to ecological conditions in streams throughout the region.