Site Mitigation & Restoration Program

We protect and maintain California’s land and places
by setting strict standards for land restoration and cleanup

Human and Ecological Risk Office

Supplemental Guidance for Human Health Multimedia Risk Assessments of Hazardous Waste Sites and Permitted Facilities


CURRENT GUIDANCE FOR HUMAN HEALTH RISK ASSESSMENT, including the Preliminary Endangerment Assessment (PEA) Guidance, other guidances and Human Health Risk Assessment Notes are available on the HERO Human Health Risk Page: Go to HERO Human Health Risk Guidance Page.


The California Department of Toxic Substances Control (DTSC), within the California Environmental Protection Agency, has the responsibility of managing the State’s hazardous waste program to protect public health and the environment. The duties of the Human and Ecological Risk Division (HERD), formerly the Office of Scientific Affairs, include providing scientific assistance in the areas of toxicology, risk and environmental assessment, training, and guidance.

Part of this assistance and guidance is the preparation of regulations, scientific guidance documents, and recommended procedures for use by regional staff, local governmental agencies, or responsible parties and their contractors in the characterization and mitigation of hazardous waste sites and permitted facilities (also referred to as hazardous substances release sites; toxic waste sites; treatment, storage, disposal facilities).

The U.S. Environmental Protection Agency (US EPA) has published a manual that provides detailed instructions for performing human health risk assessments (Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part A), Interim Final (EPA/540/1-89/002, December 1989 (HHEM)).

In addition, the US EPA Office of Solid Waste and Emergency Response (OSWER) issues directives from time to time which clarify or provide further guidance. Multimedia human health risk assessments prepared for sites or facilities over which DTSC has jurisdiction must conform to the guidance in the HHEM and OSWER directives.

This DTSC guidance manual supplements the HHEM and OSWER directives by providing recommendations on specific technical or scientific issues that may be encountered when preparing multimedia risk assessment reports for submittal and review by the DTSC.

Download Instructions

Supplemental Guidance files are divided by chapter and may be downloaded individually. Chapters three and four have been replaced and are available in the CalTOX download area at this site as documentation for that program. Chapter six is no longer relevant and has been withdrawn from the manual. The chapter designations are maintained to minimize conflict with prior releases of the manual.

Table of Contents

To download, click on the Chapter link

Please note that certain chapters are not available. Chapters 3 and 4 were replaced by CalTOX, and Chapter 6 was withdrawn.

Link File Description
Forward Forward Explaining Archived Supplemental Guidance
Chapter 1 Default Exposure Parameters
Chapter 2 Use of Soil Concentration Data in Exposure Assessment
Chapter 3
not avail.
Replaced by “CalTOX – A Multimedia Total Exposure Model for Hazardous Waste Sites Technical Reports, December 1993”
Chapter 4
not avail.
Replaced by “CalTOX – A Multimedia Total Exposure Model for Hazardous Waste Sites Technical Reports, December 1993”
Chapter 5 Selection, Use, and Limitations of Indicator Chemicals for Evaluation of Exposure to Complex Waste Mixtures
Chapter 6
not avail.
Withdrawn from the manual
Chapter 7 Assessment of Health Risks from Inorganic Lead in Soil
Chapter 8 DDT in Soil: Guidance for the Assessment of Health Risk to Humans
Chapter 9 A Toxicity Equivalency Factor Procedure for Estimating 2,3,7,8- Tetrachlorodibenzo-p-Dioxin Equivalents in Mixtures of Polychlorinated Dibenzofurans