Ecotoxicological Assessment & Modeling
EPA researchers are developing, integrating, and evaluating ecological models to predict effects of pesticides and other chemicals on endangered species and wildlife populations. High-level assessments include quantitative estimates of ecologically-relevant risk and identification of risk mitigation options. The majority of chemicals have little or no data on which to base these decisions. For these chemicals, risk assessments rely on ecological models to estimate exposure and subsequent effects.
What is a model?
A model is a computer program that attempts to simulate a particular system using algorithms and data to predict the behavior of the system being modeled.
A tiered risk assessment approach is typically used to evaluate and regulate the potential impacts of pesticides and other chemicals on ecological resources. Chemicals are first screened using rapid assessment tools that require minimal data, followed by more detailed and complex assessments for selected chemicals and scenarios. For chemicals and ecological species with limited data, assessments must rely on modeled estimates of exposure and effects.
The Ecotoxicological Assessment and Modeling (ETAM) Research Area is advancing efficient and integrated modeling approaches to improve risk assessments of chemicals with limited data, as well as data-rich applications. The integrated models span the sequence of events typical of ecological toxicity, including environmental release, fate and transport, exposure, internal dosimetry, metabolism, and toxicological responses. Further, the effects of climate change are a key consideration in developing research in this area.
Research Efforts
View recent ETAM research publications
Contaminants of Immediate and Emerging Concern
Contaminants of Immediate and Emerging Concern (CEICs) include chemicals that may cause ecological or human health impacts and are either new or existing contaminants of increased priority, such as per- and polyfluoroalkyl (PFAS) chemicals. PFAS research is guided by the objectives of EPA’s PFAS Strategic Roadmap, to meet the goals of program offices (e.g., the National PFAS Testing Strategy). EPA's ETAM research works to gather ecotoxicity information on PFAS from existing scientific literature, sampling, and monitoring ecological species (birds) and aquatic systems.
EPA's ECOTOX Knowledgebase is a comprehensive database that is continually updated with information including the toxicity and bioaccumulation of CIECs in aquatic and terrestrial organisms.
Pollinators
Pollinator assessments are a key aspect of Agency Ecological Risk Assessments as outlined in the Pollinator Protection Strategic Plan. Honeybees continue to be used as a surrogate for other species of bees and pollinators (i.e., non-Apis bees and butterflies). Methods are needed to identify exposure effects in other species of bees for which honeybees may not be a suitable representative. Some approaches to this include the development of Adverse Outcome Pathways and multi-omics (e.g., investigation of a genome or metabolome) research, as well as tools such as the Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS) tool.
Climate Change and Cumulative Impacts
The ETAM research area offers a valuable opportunity to address cross-cutting issues like climate change and cumulative impacts in an integrated way. For example, research develops and demonstrates ecological models to characterize environmental contaminants for risk assessment at national, regional, and local scales. This range of scales can be used to understand environmental conditions affecting populations experiencing disproportionate adverse impacts, for example, from climate change.
Cross-Species Extrapolation
Human and environmental risk assessments for chemicals use a limited number of model organisms to generate toxicity data, which are extrapolated to species of concern. For ecological assessments, this can involve extrapolation of effects from a few representative species to other species. Advancing approaches that rapidly maximize the use of existing data through tools such as the Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS) tool, are necessary for cross-species chemical safety evaluations.
Tools and Resources
EPA toxicity translators and models can be used to make extrapolations from available toxicity data to inform Ecological Risk Assessment under realistic exposure scenarios and refine screening estimates. This research will develop bodies of knowledge on pesticides, federally listed species, climate change, and Adverse Outcome Pathway (AOP) development.
Ecotoxicology (ECOTOX) Knowledgebase
The ECOTOX Knowledgebase is a comprehensive database that provides information on adverse effects of single chemical stressors to ecologically relevant aquatic and terrestrial species.
Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS)
Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS), is a fast, online screening tool that allows researchers and regulators to extrapolate toxicity information across species.
Other Tools and Data
- Markov Chain Nest (MCnest) Productivity Model: Estimates the impact of pesticide exposures on the reproduction success of bird populations.
- Markov Chain Nest (MCnest) Productivity Model Estimating Tool: Estimates probabilities of failure of avian reproduction in the presence of competing risks.
- Web-ICE: Estimates acute toxicity to aquatic and terrestrial organisms for use in risk assessment.
- Species Sensitivity Distribution (SSD) Toolbox: A tool that helps chemical scientists, assessors and regulators understand chemical concentrations in surface waters.