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Superfund Risk Assessment: Human Health: Toxicity (Hazard Identification and Dose Response)

Superfund Human Health
Risk Topics:

Planning and Scoping

Exposure Assessment

Acute Hazards

Toxicity (Hazard Identification and Dose Response)

Risk Characterization

Superfund Additional Risk Assessment Topics:

Risk Management

Risk Communication


View resources related to this topic from other Waste and Cleanup Risk Assessment Programs: (note - programs not linked do not have content for this topic)

Chemical Accident Prevention

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Resource and Conservation Recovery Act


Additional Superfund Information:

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Dose-Response Assessment is the process of quantitatively evaluating the toxicity of a given chemical agent as a function of human exposure to that chemical agent. The relationship between the dose of the contaminant administered or received and the incidence of adverse health effects in the exposed population forms the basis for the quantitative dose-response relationship. From these relationships, toxicity values (e.g., reference doses and slope factors) are derived that can be used to estimate the incidence or potential for adverse effects in an exposed population.

Hazard Identification is the process of determining whether exposure to a chemical agent can cause an increase in the incidence of a particular adverse health effect (e.g., cancer, birth defects) and whether the adverse health effect is likely to occur in humans. The process examines the available scientific data for a given chemical (or group of chemicals) and develops a weight of evidence to characterize the link between the negative effects and the chemical agent.

Documents | EPA Links | External Links


  1. Memorandum: Human Health Toxicity Values in Superfund Risk Assessments (Human Health Toxicity Value Hierarchy) (PDF) (4 pp, 228K, About PDF)
  2. Use of IRIS Values in Superfund Risk Assessment (PDF) (3 pp, 213K, About PDF) OSWER Directive 9285.7-16, December 21, 1993
    This memorandum clarifies the policy stated at section 7.4.1 of the December 1988 Risk Assessment Guidance for Superfund (Volume I) Human Health Evaluation Manual (Part A) (RAGS) on the use of Integrated Risk Information System (IRIS) values in performing health risk assessments.
  3. Reference Dose (RfD): Description and Use in Health Risk Assessments 1993
    This concept paper describes the U.S. Environmental Protection Agency's (U.S. EPA) principal approach to and rationale for assessing risk for health effects other than cancer and gene mutations from chronic chemical exposure.
  4. Cancer Guidelines
    EPA's Guidelines for Carcinogen Risk Assessment are intended to aid scientists in assessing the possible cancer risks caused by exposure to pollutants in the environment. Released in March 2005, the revised Cancer Guidelines integrate recent advances in scientists' understanding of the processes involved in the development of cancer.
  5. Benchmark Dose Technical Support Document External Review Draft (PDF) (96 pp, 811K, About PDF), NCEA-F-0000, October 2000. Risk Assessment Forum, Washington, DC
    The purpose of this document is to provide guidance for the Agency and the outside community on the application of the benchmark dose approach to determining the point of departure (POD) for linear or nonlinear extrapolation of health effects data.
  6. Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry 1994, EPA/600/8-90/066F
    This document describes the U.S. Environmental Protection Agency (EPA) methodology for estimation of inhalation reference concentrations (RfCs) (earlier terminology was "inhalation reference dose" or "RfDi") as benchmark estimates of the quantitative dose-response assessment of chronic noncancer toxicity for individual inhaled chemicals.
  7. Interim Policy for Particle Size and Limit Concentration Issues in Inhalation Toxicity: Notice of Availability (1994)
    EPA has made available to all interested parties, an Interim Policy for Particle Size and Limit Concentration Issues in Inhalation Toxicity Studies which deals with several of the most controversial issues encountered in inhalation toxicity studies.
  8. Guidelines for the Health Risk Assessment of Chemical Mixtures (PDF) (38 pp, 298K, About PDF) 1986, Federal Register 51(185):34014-34025.
    The guidelines are intended to guide Agency analysis of information relating to health effects data on chemical mixtures in line with the policies and procedures established in the statues administered by the EPA.
  9. Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures (PDF) EPA630-R-00-002 (August, 2001) (209pp, 1.19MB, About PDF)
    This document is a supplement to the EPA Guidelines for the Health Risk Assessment of Chemical Mixtures of 1986. The 1986 Guidelines represent the Agency's science policy and are a procedural guide for evaluating data on the health risks from exposures to chemical mixtures.
  10. Guidelines for Mutagenicity Risk Assessment
    The Guidelines for Mutagenicity Risk Assessment (hereafter Guidelines) are intended to guide Agency analysis of mutagenicity data in line with the policies and procedures established in the statutes administered by EPA.
  11. Guidelines for Neurotoxicity Risk Assessment
    These Guidelines are intended to guide Agency evaluation of agents that are suspected to cause neurotoxicity, in line with the policies and procedures established in the statutes administered by the Agency.
  12. Guidelines for Reproductive Toxicity Risk Assessment
    This notice describes the scientific basis for concern about exposure to agents that cause reproductive toxicity, outlines the general process for assessing potential risk to humans from exposure to environmental agents, and addresses Science Advisory Board and public comments on the 1994 Proposed Guidelines for Reproductive Toxicity Risk Assessment.
  13. Distributed Structure-Searchable Toxicity (DSSTox) Database Network is a project of EPA's Computational Toxicology Program, helping to build a public data foundation for improved structure-activity and predictive toxicology capabilities. The DSSTox website provides a public forum for publishing downloadable, structure-searchable, standardized chemical structure files associated with toxicity data.
  14. OncoLogicT is a desktop computer program that evaluates the likelihood that a chemical may cause cancer. OncoLogicT has been peer reviewed, runs on a Windows® PC, and is being released by EPA at no cost, to make it available to any researcher or organization wishing to evaluate cancer potential of chemicals. The OncoLogic installer is posted at the bottom of this page.
  15. Headquarters Consultation for Dioxin Sites (PDF) (2 pp, 31K,  About PDF) OSWER Directive 9200.4-19, December 13, 1996
    This document requests that CERCLA regional offices consult with EPA Headquarters on sites where remediation goals are to be developed for dioxin in soil.
  16. Approach for Addressing Dioxin in Soil and CERCLA and RCRA Sites (PDF) (6 pp, 43K,  About PDF) OSWER Directive 9200.4-26, April 13, 1998
    The purpose of this document is to recommend preliminary remediation goals (PRGs), or starting points for cleaning up dioxin in soil.
  17. EPA FAQ's about the Update to the ATSDR Policy Guideline for Dioxin and Dioxin-Like Compounds in Residential Soil (PDF) (6 pp, 39K,  About PDF)
  18. For lead risk assessment documents, please visit this webpage
  19. Bioavailability is the amount of a contaminant that is absorbed into the body following skin contact, ingestion, or inhalation. Relative bioavailability is how much of a contaminant is absorbed by humans from soil as compared to how much of that contaminant is absorbed from food or water. This Web site describes how EPA is incorporating relative bioavailability information for human exposures at Superfund sites exposed to soil contaminants via the oral pathway.
  20. Hazard Assessment (HA) for Munitions and Explosives of Concern (MEC)
  21. Assessment Guidance for Perchlorate (PDF) (2 pp, 72K, About PDF)
  22. Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons, US EPA, 1993 (PDF) (26 pp, 5.8MB, About PDF) EPA/600/R-93/089 (July, 1993).
  23. EPA Radiation Risk Assessment Guidance for Superfund sites
  24. Interim TCE Value withdrawal memo, January 15,2009 (PDF) (2 pp, 328K, About PDF)
    The Office of Solid Waste and Emergency Response has withdrawn the January 15, 2009, guidance entitled "Interim Recommended Trichloroethylene (TCE) Toxicity Values to Assess Human Health Risk and Recommendations for the Vapor Intrusion Pathway Analysis."

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EPA Links

  1. EPA Integrated Risk Information System (IRIS)
  2. Pesticide Reregistration Status
  3. Federal Drinking Water Standards
    Drinking Water Regulations and Health Advisories
  4. Handbook for Implementing the Supplemental Cancer Guidance at Waste and Cleanup Sites
    This online handbook contains information and resources for use in applying EPA's Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens (Supplemental Guidance) to cancer risk assessments at waste and cleanup sites.

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External Links

  1. Risk assessors completing risk assessments on Superfund sites may find the following Environmental Council of States (ECOS) paper: Identification and Selection of Toxicity Values/Criteria for CERCLA and Hazardous Waste Site Risk Assessments in the Absence of IRIS Values (DOC)Link to EPA's External Link Disclaimer , useful in evaluating and selecting human health toxicity values for use in risk assessments. Both EPA/OSWER and EPA/ORD scientists and risk assessors, as well as Department of Defense and California Environmental Protection Agency scientists and risk assessors, participated in the writing of this paper. These parties find the paper and its seven preferences on evaluating toxicity values useful.
  2. The U.S. Agency for Toxic Substances and Disease Registry (ATSDR)
    ATSDR developes chronic, intermediate, and acute minimal risk levels (MRLs) for some contaminants, which are considered a Tier 3 source in the OSWER hierarchy of human health toxcity values.
  3. The California Environmental Protection Agency (Cal EPA)/Office of Environmental Health Hazard Assessment Toxicity Criteria Database
    The California Environmental Protection Agency (Cal EPA)/Office of Environmental Health Hazard Assessment derives human health toxicity values, which the EPA Superfund Program sometimes uses, such as when EPA has not derived a needed toxicity value. Cal EPA toxicity assessments and values can be obtained from this Cal EPA database.
  4. The World Health Organization/International ProgrammeLink to EPA's External Link Disclaimer
    The World Health Organization/International Programme on Chemical Safety's (IPCS) Concise International Chemical Assessment Documents may also be considered a Tier 3 source, when no Tier 1 (IRIS) or Tier 2 (Provisional Peer Reviewed Toxicity Values) values are available.
  5. The 2005 World Health Organization Re-evaluation of Human and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-like CompoundsLink to EPA's External Link Disclaimer
    In 1998 and again in 2005 the World Health Organization/International Programme on Chemical Safety (WHO/IPCS) evaluted the relative cancer potentcy of chlorinated dioxins, chlorinated dibenzofurans and some polychlorinated biphenyls (PCBs) and derived toxicity equivalency factors (TEFs) which can be used in conjunction with cancer toxicity values from other sources to evaluate the cancer risk of these contaminants. The EPA Superfund Program supports the use of the current (2005) TEFs from the WHO/IPCS, which are presented in this document.

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