Models for Pesticide Risk Assessment
When EPA assesses the risk of a pesticide to human health or the environment, it considers the toxicity of the pesticide as well as the amount of pesticide to which a person or the environments may be exposed. In assessing exposure, scientists frequently use mathematical models to predict pesticide concentrations in food, water, residential, and occupational environments.
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OPP uses aquatic models to estimate pesticide concentrations in food, water, non-target organisms, residential and occupational environments. These estimated concentrations are used to assess exposure to aquatic organisms, humans, and the environment. More information about water models.
Surface Water Models
The Surface Water Concentration Calculator (SWCC) estimates pesticide concentrations in water bodies that result from pesticide applications to land. The SWCC is designed to simulate the environmental concentration of a pesticide in the water column and sediment and is used for regulatory purposes by the USEPA Office of Pesticide Programs (OPP). The SWCC uses PRZM version 5.0+ (PRZM5) and the Variable Volume Water Body Model (VVWM), replacing the older PE5 shell (last updated November 2006), which used PRZM3 (Carousel et al., 2005) and EXAMS (Burns, 2003). This updated model will improve users' interactions with the program and facilitate maintenance and operation of the software.
- Executable Installation
- SWCC Executable (SWCC.msi)(1 pg, 2 MB)
- Source Code
- Crop Scenarios
- SWCC Crop Scenarios (cropscenarios-swcc.zip)(1 pg, 69 K)
- Surface Water Concentration Calculator User Manual (PDF) (21 pp, 168 K, 12June2014, USEPA/OPP 734F14001)
- PRZM5 A Model for Predicting Pesticide in Runoff, Erosion, and Leachate: User Manual (PDF) (55 pp, 687 K, 01July2014, USEPA/OPP 734F14002)
- The Variable Volume Water Model (PDF) (38 pp, 227 K, 12June2014, USEPA/OPP 734F14003)
PFAM is an aquatic model used to estimate surface water exposure from the use of pesticides in flooded fields. In comparison to the current Tier 1 rice model, PFAM allows for more advanced evaluation of pesticide use on flooded agricultural areas such as rice paddies and cranberry bogs. The advanced capabilities of PFAM include accounting for water and pest management practices and for degradation in soil and aquatic environments, as well as for post processing of discharged paddy waters to a stream, index reservoir, farm pond, or other user-defined receiving water.
- PFAM Executable (MSI)(1 pg, 2 MB)
- Pesticides in Flooded Applications Model (PFAM): Conceptualization, Development, Evaluation, and User Guide (PDF) (61 pp, 954 K, 18July2013, EPA-734-R-13-001)
FIRST is a surface water model that is used to assess exposure to pesticides in drinking water.
FIRST Version 1.0
- FIRST Version 1.0 Executable (EXE)(1 pg, 74 K)
- FIRST Version 1.0 Source Code (Fortran 77)(1 pg, 46 K) Delete the _.txt to use the file as first.for
- Users Manual
FIRST Version 1.1.1
- FIRST Version 1.1.1 Executable (EXE)(1 pg, 590 K)
- FIRST Version 1.1.1 Source Code (Fortran 77)(1 pg, 46 K) Delete the _.txt to use the file as first_version1_1_1.for
- Users Manual
KABAM is used to estimate potential bioaccumulation of hydrophobic organic pesticides in freshwater aquatic food webs and subsequent risks to mammals and birds via consumption of contaminated aquatic prey.
- KABAM Version 1.0 Executable (XLS)(1 pg, 161 K)
- User's Guide and Technical Documentation | Information and link to the PDF Version
Tier I Rice Model is an aquatic model used to estimate surface water exposure from the use of pesticides in rice paddies.
Ground Water Models
PRZM-GW (Pesticide Root Zone Model for GroundWater) is used as a screening-level and refined tool for risk assessment purposes. In general, PRZM-GW provides conservative estimates of pesticide concentrations in groundwater, but it also allows for region specific scenario development in cases where refined drinking water assessments are needed.
- PRZM-GW Version 1.07 Executable (PRZMGW.msi)(1 pg, 2 MB)
- Guidance for Using PRZM-GW in Drinking Water Exposure Assessments
- Guidance for Selecting Input Parameters for Modeling Pesticide Concentrations in Groundwater Using the Pesticide Root Zone Model
- Model and Scenario Development Guidance for Estimating Pesticide Concentrations in Groundwater Using the Pesticide Root Zone Model
- PRZM-GW Version 1.07 - Scenarios (ZIP)(1 pg, 105 K)
- DRAFT Final Report. Identification and Evaluation of Existing Models for Estimating Environmental Pesticide Transport to Groundwater. A North American Free Trade Agreement (NAFTA) Project.
SCIGROW is an aquatic model used to estimate pesticide concentrations in ground water.
- SCI-GROW Executable sg23.exe(1 pg, 344 K)
- SCI-GROW Source Code (scigrow.f90.txt)(1 pg, 4 K) (Fortran 90) Delete the .txt extension to use the file as scigrow.f90
- User's Manual for Version 2.3 is under development
EXPRESS is designed to facilitate a rapid and consistent assessment of aquatic pesticide exposure on a variety of crops. EXPRESS is a joint project of the USEPA Office of Pesticide Programs' Environmental Fate and Effects Division (OPP/EFED) and the USEPA Office of Research and Development (ORD). View EXPRESS (EXAMS - PRZM Exposure Simulation Shell).
SWAMP is a probabilistic model that estimates the probability, magnitude, and certainty of the risk to aquatic organisms from exposure to pesticides. Information for this model is available in EPA's Web archive. Search EPA Archive
Additional Information Related to Water Models
- Environmental Modeling Public Meeting - Information
- Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides
- Positive Attributes and Desired Qualities for Models
- Development and Use of the Index Reservoir in Drinking Water Exposure Assessments
- Development of Community Water System Drinking Water Intake Percent Cropped Area Adjustment Factors for use in Drinking Water Exposure Assessments: 2014 Update
- Finalization of Guidance on Incorporation of Water Treatment Effects on Pesticide Removal and Transformations in Drinking Water Exposure Assessments
- Golf Course Adjustment Factors for Modifying Estimated Drinking Water Concentrations and Estimated Environmental Concentrations Generated by Tier I (FIRST) and Tier II (PRZM/EXAMS) Models
- Guidance for Making Temperature Adjustments to Metabolism Inputs to EXAMS and PE5
- Relevant SAP Sessions
- Water Models - Previous Versions
OPP uses terrestrial models to estimate pesticide concentrations on avian and mammalian food items and exposure and risk to terrestrial organisms from pesticide use.
MCnest integrates existing toxicity information from three standardized avian toxicity tests with information on species life history and the timing of pesticide applications relative to the timing of avian breeding seasons, to quantitatively estimate the impact of pesticide-use scenarios on the annual reproductive success of bird populations. View information about MCnest.
SIP is used by OPP to provide an upper bound estimate of exposure of birds and mammals to pesticides through drinking water alone.
STIR is used by OPP to estimate inhalation-type exposure based on pesticide-specific information.
T-REX is used by OPP to estimate pesticide concentration on avian and mammalian food items.
- T-REX Version 1.5.2 Executable (XLSM)(10 pp, 585 K,
- 6/6/2013, v. 1.5.2 Seeding rate inputs were corrected to accurately reflect data from Becker and Ratnayake, 2011. Comment sheet was removed from the model due to lack of functionality.
- User Guide
- User Guide Version 1.5 remains current
TIM is used by OPP to derive quantitative estimates of the probability (or likelihood) and magnitude of mortality to birds (of the same species) exposed to the simulated pesticide.
The TIM executable and graphical user interface (GUI) should be unzipped and saved to the directory of the user's choosing. In order to run the GUI, the Matlab Compiler Runtime (MCR) must be installed on the user's computer. It can be downloaded free of charge from the ExitMathworks Exitwebsite. The required version is the Windows 32-bit MCR for Matlab release 2012a. A full technical description of TIM v. 3.0 beta is provided in the manual (and associated appendices). User's guidance on running and parameterizing the model is provided in Appendix A.
- TIM Version 3.0 beta - TIM Executable and Graphical User Interface (GUI) (ZIP)(1 pg, 249 K)
- Technical Description and User's Guidance
- Appendix A - User's Guidance for TIM v.3.0 (beta)
- Appendix B - Example input file for TIMv3.0 (with parameter descriptions in /* */)
- Appendix C - Parameters used in TIM v3.0
- Appendix D - Avian Data to Support Generic and Custom Species
- Appendix E - Initial Pesticide Residues on Arthropods
- Appendix F - Approach for Calculating Juvenile Dietary Exposure
- Appendix G - Equation for Calculating Home Range for Insect Eating Birds
- Appendix H - Dermal Toxicity Estimation
- Appendix I - Overview and History of Tiered Risk Assessment Framework
- Appendix J - Method for Deriving Species Sensitivity Distributions
TerrPlant is a Tier 1 model providing screening-level estimates of exposure to terrestrial plants from single pesticide applications.
T-HERPS is a simulation model that estimates exposure to terrestrial reptiles and amphibians from pesticide use.
OPP uses atmospheric models to predict the deposition patterns of pesticides released into the atmosphere.
AgDRIFT® (version 2.1.1), a modified version of the AGricultural DISPersal (AGDISP®) model developed by the US Forest Service, was created under a Cooperative Research and Development Agreement between the EPA, the US Department of Agriculture's Forest Service, and the Spray Drift Task Force. The AgDRIFT® model has the capability to assess a variety of spray drift conditions from agricultural applications and off-site deposition of liquid formulation of pesticides. This model can be used in estimating downwind deposition of spray drift from aerial, ground boom and orchard/vineyard airblast applications.
- AgDRIFT (Version 2.1.1) (ZIP)(1 pg, 12 MB)
AGDISP® (version 8.26) is a "first-principles" science-based model that predicts spray drift from application sites. The model was developed by the USDA Forest Service. AGDISP® was designed to optimize agricultural spraying operations and has detailed algorithms for characterizing the release, dispersion, and deposition over and downwind of the application area. This model can be used in estimating downwind deposition of spray drift from aerial and ground boom applications. In addition, it can be used in estimating downwind deposition of spray drift from forestry and adulticide/mosquitocide applications. The research version of AGDISP model can be obtained from Dr. Harold W. Thistle, USDA Forest Service.
- AGDISP® (version 8.26) (ZIP)(1 pg, 7 MB)
SOFEA system is used to calculate exposure to bystanders who are in proximity to fileds treated with soil fumigants. View information in the archive about the 9/9/2004 FIFRA Scientific Advisory Committee. Search EPA Archive
FEMS is used to calculate exposure to bystanders who are in proximity to fields treated with soil fumigants. View information in the archive about the 8/26/2004 FIFRA Scientific Advisory Committee meeting. Search EPA Archive
OPP uses health effects models to predict effects to humans from exposure to pesticides.
DEEM provides dietary probabilistic assessments of dietary pesticide exposure. CALENDEXTM - FCID evaluates aggregated exposure that appropriately incorporates the probability of simultaneous exposures across multiple pathways.
CARES is currently available, but a new version is under development. This new version will offer enhancements such as automatically importing certain data, but further review is required before it will be made available. View information about the current version of CARES by the International Life Sciences Institute. Exit
The FIFRA Scientific Advisory Panel reviewed CARES in 2004. Information from this meeting is available in the archives. Search EPA Archive (Use CARES SAP as your search term.)
The Indirect Dietary Residential Exposure Assessment Model (IDREAM) was developed to estimate acute and chronic indirect ingestion exposure that can result from use of disinfectants and sanitizers on kitchen surfaces in residential settings. It provides guidance for estimating these exposures where there may be inadvertent transfer of residue to edible items prepared on surfaces treated with these pesticides. View the IDREAM model.
Describes data sources used in exposure and risk assessment of occupational pesticide handlers (i.e., mixer/loaders and applicators). Includes the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table". View information about OPHED.
Describes data sources used in assessment of occupational post-application exposures (e.g., harvesting, weeding, etc.). Includes "Science Advisory Council for Exposure, Policy 3". View information about OPPED.
This model has been replaced by CARES and the residential exposure standard operating procedure. Information about this model is available in the archive (FIFRA SAP meeting for 9/26/2003). Search EPA Archive Use REX SAP as your search term.
SHEDS is a physically-based stochastic model developed to quantify exposure and dose of humans to multimedia, multipathway pollutants. View information in the archive about the 8/30/2002 FIFRA Scientific Advisory Committee meeting. Search EPA Archive
SWIMODEL is a screening tool for conducting exposure assessment of pesticides found in indoor swimming pools and spas. View the SWIMODEL.
View information in the archive about the 12/11/2003 FIFRA Scientific Advisory Committee meeting. Search EPA Archive