Engineering and Expeditionary Warfare Center

Human Health Risk Assessment

HHRA

Overview

 

The human health risk assessment (HHRA) process plays an important role in protecting potential human receptors from current and future threats posed by contaminants released into the environment. The proposed approach for the HHRA should be presented to stakeholders early on in the cleanup process to facilitate concurrence.

Jump to Resources to access Policies & Guidance, Publications, Related Sites, and Tools

 

Process

 

The Department of the Navy’s (DON’s) three-tiered HHRA approach closely mirrors the United States Environmental Protection Agency (EPA) Risk Assessment Guidance for Superfund (RAGS) process. The DON HHRA Guidance provides details on what should be included and considered in each tier of an HHRA, discussion on technical issues, and description of tools available to assist in HHRAs. All sites are required to complete a Tier 1 risk assessment. A Tier 2 risk assessment is conducted if the site is found in the Tier 1 evaluation to pose potentially unacceptable risks to human health. If further action is required, a Tier 3 risk evaluation of remedial alternatives is necessary. The key elements of the three-tiered HHRA approach are described below:

  • Tier 1 includes a screening risk assessment (SRA) to develop the conceptual site model (CSM), identify complete exposure pathways, and evaluate the analytical data to ensure data quality objectives (DQOs) for risk-based screening have been achieved. The SRA compares site maximum chemical concentrations to risk-based concentrations (RBCs). RBCs are concentrations of chemicals in soil, air, and water that are considered protective of human health. The required Tier 1A review results in a list of chemicals that can be eliminated from further consideration and/or a list of chemicals of potential concern (COPCs) based upon a comparison to existing RBCs derived using standard calculations. The optional Tier 1B review involves an SRA conducted using RBCs that are calculated based on site-specific input to determine acceptable concentrations of chemicals in each medium.
  • The Tier 2 baseline human health risk assessment (BHHRA) incorporates site-specific information to calculate carcinogenic risk and noncarcinogenic health hazard estimates. Only chemicals attributable to a release and not consistent with background levels at the site are carried through for Tier 2 evaluation. A key aspect of the BHHRA is the study design including current and future land use scenarios, data collection and analytical methods, exposure scenarios, exposure concentrations, and the statistical analysis to be used in the risk estimation. The carcinogenic risks and noncarcinogenic hazards calculated in the BHHRA are used to document the magnitude of risk at a site, the primary contributors to that risk, and whether or not a remedial action is necessary at the site.
  • The Tier 3 risk evaluation of remedial alternatives (RERA) is the evaluation of the remedial alternatives with regards to: (1) the effectiveness of reducing risks to acceptable levels; (2) human health impacts related to remedy implementation; and (3) residual risks that will remain at a site. The purpose of the RERA is to provide remedial project managers (RPMs) with an assessment of the potential short and long-term health risks associated with the remedial alternatives. As part of the RERA process, risk-based preliminary remedial goals (PRGs) are calculated similar to how RBCs are calculated in the Tier 1 SRA, but refined based on the selected remedial actions and site-specific information.

 

For more information, Chapter 8.3.3.1 of the DON Environmental Restoration Program Manual provides a detailed description of the HHRA approach.

Resources

 

Topics

Title and Description

ERP Manual

DON Environmental Restoration Program Manual: Chapter 8.3.3.1 Human Health Risk Assessment (February 2018)

Describes the overall approach for conducting HHRAs and specifies that a three-tiered risk assessment approach be implemented.

DON Guidance

Human Health Risk Assessment

U.S. Navy Human Health Risk Assessment Guidance (December 2008)

Provides details on what should be included and considered in each tier of an HHRA, discussion on technical issues, and description of tools available to assist in the completion of HHRAs. 

DON Guidance

Human Health Risk Assessment

Risk Characterization for Chemicals with Mutagenic Mode of Action: Supplemental Guidance for Conducting Human Health Risk Assessments (February 2008)

A supplement to the DON HHRA Guidance focusing on chemicals with a mutagenic mode of action and how to calculate the cancer risk for these chemicals in an HHRA.

Navy Policy

Human Health Risk Assessment

Navy Policy for Conducting Human Health Risk Assessment under the Environmental Restoration Program (February 2001)

This policy provides direction on how to conduct HHRAs and describes a three-tiered HHRA approach with criteria for exiting the process at each tier. 

Background

Background Chemicals

Navy Policy on the Use of Background Chemical Levels (January 2004)

Clarifies the Navy’s position on consideration of background chemical levels.

Soil Background

NAVFAC Guidance for Environmental Background Analysis Volume I: Soil (April 2002)

Provides instructions for characterizing background conditions at sites where past uses of the property have resulted in actual or suspected chemical releases to soil.

Background Chemicals

NAVFAC Guidance for Environmental Background Analysis: Volume II Sediment (April 2003)

Provides instructions for the characterization of background conditions at sediment sites where past uses of the property may have resulted in chemical releases.

Groundwater Background

NAVFAC Guidance for Environmental Background Analysis Volume III: Groundwater (April 2004)

Provides instructions for characterizing groundwater background conditions and comparing datasets for impacted groundwater based on statistical methods and geochemical relationships.

Background Chemicals

NAVFAC Guidance for Environmental Background Analysis Volume IV: Vapor Intrusion Pathway (April 2011)

Reviews methodologies for assessing potential background sources to indoor air as a part of the assessment of the vapor intrusion pathway.

Bioavailability

Bioavailability

Human Health

Tri-Service Environmental Risk Assessment Workgroup (TSERAWG) Guide for Incorporating Bioavailability Adjustments into Human Health and Ecological Risk Assessments at DoD Facilities Part 1: Overview of Metals Bioavailability (June 2003)

Includes a primer on the concept of bioavailability and how it can be used in determining risk levels.

Bioavailability

Human Health

TSERAWG Guide for Incorporating Bioavailability Adjustments into Human Health and Ecological Risk Assessments at DoD Facilities Part 2: Technical Background Document for Assessing Metals Bioavailability (June 2003)

Provides more in-depth technical information for professionals involved in designing and performing bioavailability studies.

Topics

Title and Description

Soil Properties

Metals Bioavailability

The Effect of Soil Properties on Metal Bioavailability (June 2013)

Validates the relationships between soil properties and in vitro methods that can serve as a screening tool for estimating in vivo toxic metal bioavailability in soil.

TCE Toxicity

NAVFAC Trichloroethene (TCE) Toxicity Values Fact Sheet (March 2012)

Reviews updated toxicity values for TCE to be used in risk assessment.

Negotiation

NAVFAC Risk Assessment Workgroup Issue Paper: Environmental Negotiation Primer (June 2011)

Describes basic principles of negotiation to facilitate productive negotiation outcomes.

 

HHRA

Non-default exposure

 

NAVFAC Risk Assessment Workgroup Quick Reference Guide: Assessing Non-Default Exposures in Human Health Risk Assessment (April 2011)

Provides examples of non-default HHRA exposure scenarios and guidance so RPMs can recognize the types of exposure scenarios that may arise and when they may be applicable to their sites.

Groundwater

Cleanup Goals

NAVFAC Risk Assessment Workgroup Issue Paper: Evaluation of Site-Specific Criteria for Determining Potability and Cleanup Goals for Impacted Groundwater (March 2011)

Clarifies criteria for determining EPA's Groundwater Beneficial Use Classification in order to establish appropriate cleanup goals for groundwater sites.

 Response Triggers for Emerging Contaminants

Department of Defense (DoD) Memorandum: Actions in Response to Releases of Emerging Contaminants; Enclosure: Environmental Council of the States (ECOS)-DoD Sustainability Work Group Issue Paper on Emerging Contaminants - Initiation of Characterization and Response Actions for Protection of Human Health (September 2008)

Examines some key conditions, considerations, statutory authorities, or criteria that could be used to evaluate potential characterization and response actions for emerging contaminants.

Detection Limits

Reporting Limits

Laboratory Detection and Reporting Limit Issues Related to Risk Assessments (April 2002)

Provides an overview of detection and reporting limits issues that can affect the ability to meet data quality objectives for risk assessments.

Topics

Title and Description

toxicity

exposure 

EPA Integrated Risk Information System (IRIS)

The IRIS database provides Tier 1 human health toxicity information for the EPA Superfund Program and toxicity values for health effects resulting from chronic exposure to chemicals.

Screening

Levels

 

EPA Regional Screening Levels (RSLs) Calculator

The purpose of this calculation tool is to assist risk assessors, RPMs, and others involved with risk assessment and decision-making in developing RSLs.

 

 

Resident 

Vapor Intrusion 

EPA Resident Vapor Intrusion Screening Levels (VISLs)

A quick reference spreadsheet summarizing the results of implementing the VISL calculator.

 

 

toxicity

values 

EPA and DOE Oak Ridge National Laboratory (ORNL) Provisional Peer Reviewed Toxicity Values (PPRTV) Database

An electronic library of toxicity values representing Tier 2 human health toxicity values for the EPA Superfund Program. These values have been developed specifically for EPA's Superfund Program, but have not undergone the multi-program review and consensus required for toxicity values to be placed in IRIS.

decision

screening level 

DOE ORNL Risk Assessment Information System (RAIS) Preliminary Remediation Goals (PRG) Calculator

The purpose of this calculation tool is to assist risk assessors, RPMs, and others involved with risk assessment and decision-making in developing screening levels. It is similar to the EPA RSL calculator tool.

 

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