Aquatic Life Benchmarks and Ecological Risk Assessments for Registered Pesticides

The Office of Pesticide Programs’ Aquatic Life Benchmarks for freshwater species and the Office of Water’s Ambient Water Quality Criteria (when available) for registered pesticides in the United States are provided in the table below. Aquatic Life Benchmarks may be used in conjunction with environmental chemistry methods (ECMs), which are analytical methods for detecting pesticide residues, primarily in soil or water. State, tribal, and local governments can use the Aquatic Life Benchmarks in identifying and prioritizing sites and pesticides that may require further investigation.

The table below was updated as of August 22, 2024, and new/updated benchmarks are shown below in red and bolded. Read a summary of the August 2024 updates to the Aquatic Life Benchmarks. EPA intends to update Aquatic Life Benchmarks on an annual basis.

The benchmarks are based on toxicity values from scientific studies that EPA reviewed and used to estimate risk to freshwater organisms from exposure to pesticides and their degradates in their most recent publicly available ecological risk assessments and preliminary Problem Formulations written in support of pesticide registration or registration review. The toxicity studies are responsive to data requirements specified in U.S. Code of Federal Regulations (40 CFR 158). EPA uses Harmonized Test Guidelines and the Evaluation Guidelines for Ecological Toxicity Data in the Open Literature to evaluate the quality and utility of the studies. For each of the chemicals listed, the table provides a link to the source documents from which each of the benchmarks is extracted.

• Relationship to ambient water quality criteria
• Use of Aquatic Life Benchmarks
• OPP Aquatic Life Benchmarks
• Footnotes
• Definitions

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Relationship to Ambient Water Quality Criteria

EPA's Office of Pesticide Programs (OPP) and EPA's Office of Water (OW) have responsibilities for evaluating aquatic toxicity data to assess the ecological effects of chemicals in surface water. Effects assessments under both program offices are developed with high quality data according to parallel but somewhat different rigorously peer-reviewed assessment methods.

• OW uses aquatic toxicity data to develop ambient water quality criteria that can be adopted by states and tribes to establish water quality standards under the Clean Water Act. Procedures for deriving the criteria are described in OW’s Guidelines for Deriving Numerical National Water Quality Criteria for Protection of Aquatic Organisms.
• As required by the Federal Insecticide, Fungicide, and Rodenticide Act, OPP uses aquatic toxicity data in its ecological risk assessments to inform pesticide registration decisions. OPP's procedures for conducting pesticide effects assessments are described in the Overview of the Ecological Risk Assessment Process.
• Both the OW and OPP methods assess and characterize effects for protecting aquatic communities.

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Use of Aquatic Life Benchmarks

EPA worked initially with the U.S. Geological Survey to identify aquatic ecotoxicity benchmark values from risk assessments developed by EPA for individual pesticides during previous re-registration programs. The Overview of the Ecological Risk Assessment Process and ecological risk assessments developed for individual pesticides provide an understanding of the ecotoxicity data used to develop benchmarks. Comparing a measured concentration of a pesticide in water with an Aquatic Life Benchmark can be helpful in interpreting monitoring data and in identifying and prioritizing sites and pesticides that may require further investigation.

The toxicity data used to develop Aquatic Life Benchmarks are extracted from the most recent publicly available OPP risk assessment for the individual pesticide and are typically based on the most sensitive value for each taxon. Aquatic Life Benchmarks are estimates of the concentrations below which pesticides are not expected to represent a risk of concern for aquatic life. EPA developed the Aquatic Life Benchmarks independent of any protection standard or requirement under the Endangered Species Act (ESA); therefore, the Aquatic Life Benchmarks do not necessarily equate to any particular finding under the ESA.

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Footnotes

• ^A Benchmark = Toxicity value x LOC. For acute Fish, toxicity value is generally the lowest 96-hour LC50 in a standardized test (usually with Rainbow Trout (Oncorhynchus mykiss); Fathead Minnow (Pimephales promelas); Bluegill Sunfish (Lepomis macrochirus)), and the LOC is 0.5.

• ^B Benchmark = Toxicity value x LOC. For chronic Fish, toxicity value is usually the lowest NOEAC from a life-cycle or early life stage test (usually with Rainbow Trout (Oncorhynchus mykiss) or Fathead Minnow (Pimephales promelas), and the LOC is 1.

• ^C Benchmark = Toxicity value x LOC. For acute invertebrate, toxicity value is usually the lowest 48- or 96-hour EC₅₀ or LC₅₀ in a standardized test, and the LOC is 0.5.

• ^D Benchmark = Toxicity value x LOC. For chronic invertebrates, toxicity value is usually the lowest NOAEC from a life-cycle test with invertebrates, and the LOC is 1.

• ^E Benchmark = Toxicity value x LOC. For nonvascular plants, toxicity value is usually a short-term (less than 10 days) EC₅₀ (usually with green algae or diatoms), and the LOC is 1.

• ^F Benchmark = Toxicity value x LOC. For vascular plants, toxicity value is usually a short-term (less than 10 days) EC₅₀ (usually with duckweed) and the LOC is 1.

• ^G Benchmark = Toxicity endpoints for the fipronil degradate desulfinyl were compared to EECs and, although they were not used to calculate risk quotients, did preclude risk to these degradates as well.

• ^H Benchmark = The nonvascular plant endpoint was used as a surrogate for vascular plants.

• ^I Benchmark = This is the second-most sensitive value obtained for this degradate; the most sensitive value obtained for this degradate (14.9 ug ai/L) is classified as supplemental and for qualitative use only.

• ^J Benchmark = These values were not used to estimate risk since exposure to aquatic animals is not expected.

Generic footnotes

• Empty cells indicate that acceptable aquatic toxicity values are not available.

• Benchmarks preceded by a "greater-than" symbol (for example, >265,000) were derived from a "greater-than" value and may overestimate toxicity.  Conversely, benchmarks preceded by a "less-than" symbol (for example, <1,500) were derived from a "less-than" value and may underestimate toxicity.

• Values in bold and red are those that changed in the August 2024 update.

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Definitions

• EC₅₀ = 50 percent effect concentration

• LC₅₀ = 50 percent lethal concentration

• LOC = level of concern

• NOAEC = no-observed-adverse-effects concentration

• NR = Not reported in study used to derive benchmark.

• µg/L = microgram per liter

• — = no benchmark available