EPA Research

Human Health Risk Assessment Research Methods, Models, Tools, and Databases


  • Acute-to-Chronic Estimation (ACE)
    ACE with Time-Concentration-Effect Models software allows prediction of chronic toxicity from acute toxicity datasets. ACE uses linear regression and accelerated life testing to predict no-effect and low-effect concentrations for chronic mortality.
  • All-Ages Lead Model (AALM)
    The All Ages Lead Model (AALM) guidance will predict lead concentration in body tissues and organs for a hypothetical individual, based on a simulated lifetime of lead exposure. Statistical methods will be used to extrapolate to a population of similarly exposed individuals. The purpose of the model is to provide risk assessors and risk managers with a tool for rapidly evaluating the impact of possible sources of lead in a specific human setting where there is a concern for potential or real human exposure to lead.
  • Exposure Model for Soil-Organic Fate and Transport (EMSOFT)
    EMSOFT is a computer screening model that may be used 1) to determine concentrations of contaminants remaining in the soil over a given time (when the initial soil concentration is known); 2) to quantify the mass flux (rate of transfer) of contaminants into the atmosphere over time; and 3) to calculate contaminant air concentrations by inputting mass flux values into atmospheric dispersion models.
  • Stochastic Human Exposure and Dose Model for Multimedia, Multipathway Chemicals (SHEDS-Multimedia)
    SHEDS is a physically-based, probabilistic model that can simulate cumulative (multiple chemicals) or aggregate (single chemical) exposures over time for a population via residential and dietary routes of exposure for a variety of multimedia, multipathway environmental chemicals
  • Physiologically Based Pharmacokinetic (PBPK) Models
    The purpose of this final report is to serve as a learning tool for scientists and risk assessors, as well as highlight the benefits of using PBPK modeling. The report can also be informative to PBPK modelers, as it describes the types of data and models that the EPA requires for consideration of a model for use in risk assessment. The report gives an overview of PBPK modeling and the data needed to develop these models, as well as provides considerations for evaluating these models prior to using them to perform interspecies, intraspecies, and other extrapolations needed in risk assessment.

Top of Page


  • Benchmark Dose Software (BMDS)
    BMDS is a tool which is used to facilitate the application of benchmark dose (BMD) methods to EPA hazardous pollutant risk assessments.
  • CATREG Software for Categorical Regression Analysis
    CatReg is used to perform categorical regression analyses on toxicity data after effects have been assigned to ordinal severity categories (e.g., no effect, adverse effect, severe effect) and associated with up to two independent variables corresponding to the exposure conditions (e.g., concentration and duration) under which the effects occurred.
    Research question: How can I calculate the probabilities of the different severity categories over the continuum of the variables describing exposure conditions?
  • Community-Focused Exposure and Risk Screening Tool (C-FERST)
    C-FERST is a community mapping, information access, and assessment tool designed to assess risks and assist in decision making within communities.
    Research question: How can I prioritize my/a community's environmental exposures and risks, and learn about potential solutions to inform environmental public health decision-making?
  • EPA Environmental Assessment Framework Documents
    The framework documents are peer-reviewed documents stating overarching principles and practices to be followed.
  • EPA Guidance Documents & Handbooks
    The guidance documents and handbooks are peer-reviewed document stating overarching principles and practices to be followed.
  • Children's Exposure Factors Handbook - 2008 edition
    Highlights of the Child-Specific Exposure Factors Handbook
    The goal of the Child-Specific Exposure Factors Handbook and the Highlights document is to consolidate all child exposure data into one single document. This document provides a summary of the available and up-to-date statistical data on various factors assessing child exposures.
    Research question: What are the human behaviors and characteristics that influence exposure to environmental contaminants? What is the variability of those behaviors and characteristics with regard to children?
  • Example Exposure Scenarios Tool
    The purpose of the Example Exposure Scenarios is to outline scenarios for various exposure pathways and to demonstrate how data from the Exposure Factors Handbook may be applied for estimating exposures. The example scenarios presented here have been selected to best demonstrate the use of the various key data sets in the Exposure Factors Handbook and represent commonly encountered exposure pathways. An exhaustive review of every possible exposure scenario for every possible receptor population would not be feasible and is not provided. Instead, readers may use the representative examples provided here to formulate scenarios that are appropriate to the assessment of interest, and apply the same or similar data sets and approaches as shown in the examples.
  • Exposure Factors Handbook - 2011 edition
    Highlights of the Exposure Factors Handbook
    The Exposure Factors Handbook and the Highlights document summarize data on drinking water consumption, inhalation rates, and other factors that influence subject exposure to environmental contaminants.
    Research question: What are the human behaviors and characteristics that influence exposure to environmental contaminants? What is the variability of those behaviors and characteristics with regard to specific life stages?
  • Integrated Risk Information System (IRIS)
    IRIS is a human health assessment program that evaluates information on health effects that may result from exposure to environmental contaminants. IRIS provides public access to information on more than 550 chemical substances that have undergone IRIS assessment.
    Research question: What are the important human health effects of chemicals for priority Agency decisions?
  • Tox21
    Tox 21 is pooling federal resources and expertise from EPA, National Institutes of Environmental Health Sciences/National Toxicology Program, National Institutes of Health and the Food and Drug Administration to use robotics technology to screen thousands of chemicals for potential toxicity, use screening data to predict the potential toxicity of chemicals and develop a cost-effective approach for prioritizing the thousands of chemicals that need toxicity testing.
  • Toxicological Priority Index (Tox Pi)
    ToxPi is a flexible prioritization support software tool that incorporates ToxCast bioactivity profiles, inferred toxicity pathways, dose estimates and chemical structural descriptors to:
    • Calculate the comprehensive toxicity potential.
    • Provide a visual that represents relative contribution of each data domain to an overall priority score.
    • Show a new weight-of-evidence framework for diverse prioritization related to systematic, cancer, developmental or reproductive toxicity testing.
    • Numerically integrate multiple information domains.
  • Virtual Embryo (v-Embryo)
    The v-Embryo project aims to accurately predict the potential for environmental chemicals to affect the embryo. A selection of everyday chemicals with known health effects in animal tests are used to determine if it is possible to use a virtual embryo model to predict the potential developmental toxicity of chemicals.
  • Virtual Liver (v-Liver)
    The v-Liver project aims to estimate the potential of chemicals to cause chronic diseases such as cancer using computer models and simulation.

Top of Page


  • Aggregated Computational Toxicology Resource (ACToR)
    An online warehouse of publicly availably chemical toxicity data from over 1,000 public sources on over 500,000 environmental chemicals.
    Research question: What public data is available to assess the toxicity of chemicals?
  • Biomarkers Database
    The Biomarkers Database was developed by assembling and evaluating the literature relevant to human biomarkers. It catalogues and evaluates the usefulness of biomarkers of exposure, susceptibility and effect which may be relevant for a longitudinal cohort study. In addition to describing currently available, reliable human biomarkers, the report also reviews up-and-coming techniques and biomarkers in animal models that could be tested for application in human studies.
  • Database of Sources of Environmental Releases of Dioxin-like Compounds in the United States
    The database is a repository of certain specific chlorinated dibenzo-p-dioxin/dibenzofuran (CDD/CDF) emissions data from all known sources in the US. The database contains information that can be analyzed to track emissions of CDD/CDF over time, compare specific profiles between and among source categories, and develop source specific emission factors that can then be used to develop emission estimates.
  • DSS Tox
    DSSTox is a resource for high quality chemical structures and chemical annotation in association with toxicity data. The database publishes summarized activity representations for structure-activity modeling. It also provides the chemical information management & cheminformatics foundation for ToxCast and Tox21 projects.
  • ExpoCast Database
    ExpoCast is a database with increasing data and functionality. Long term, the database will consolidate observational human exposure data and link to ToxRefDB, ACToR, and ToxCast to help make high throughput exposure predictions. Currently, the database contains consolidated observational human exposure data and improves access and linkages to health related data. Research question: How can knowledge of exposures inform risk-based decision making?
  • Health & Environmental Research Online (HERO)
    The database includes more than 600,000 scientific references and data from the peer-reviewed literature used by EPA to develop its regulations for the following: Integrated Science Assessments (ISA) that feed into the NAAQS review, Provisional Peer Reviewed Toxicity Values (PPRTV) that represent human health toxicity values for the Superfund, and the Integrated Risk Information System (IRIS), a database that supports critical agency policymaking for chemical regulation. These assessments supported by HERO characterize the nature and magnitude of health risks to humans and the ecosystem from pollutants and chemicals in the environment.
  • Physiological Information Database (PID)
    PID is used in physiologically-based pharmacokinetic (PBPK) modeling. The database contains physiological parameter values for humans from early childhood through senescence as well as similar data for laboratory animal species.
  • Toxicity Forecaster (ToxCast)
    Provides chemical testing data for in vitro high throughput screening of 300 chemicals. Data can be used to help prioritize chemicals and predict toxicity.
    Research question: How can high-throughput screening data be used to predict potential toxicity, prioritize chemicals and inform chemical risk assessments?
  • Toxicity Reference Database (ToxRefDB)
    ToxRefDB contains thousands of animal toxicity studies on hundreds of chemicals from 30 years worth of animal toxicity studies.
    Research question: What animal toxicity data is available to help assess the toxicity of chemicals?

Top of Page