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Human Health Risk (HERO)

 

HUMAN HEALTH RISK ASSESSMENT GUIDANCE

Use of the Northern and Southern California Polynuclear Aromatic Hydrocarbon (PAH) Studies in the Manufactured Gas Plant Site Cleanup Process  (July 1, 2009) The purpose of this advisory is to describe how the ambient conditions for carcinogenic polynuclear aromatic hydrocarbons identified by the Northern or Southern California PAH Study (i.e., the ambient data sets) might be used as a pragmatic tool in various stages of the soil cleanup process at manufactured gas plant (MGP) sites.  Additional files available for download include the Northern and Southern California PAH studies and their corresponding ambient PAH datasets.


Evaluating Human Health Risks from Total Petroleum Hydrocarbons (TPH) - Interim Guidance

This guidance document is no longer active. Future approaches to petroleum hydrocarbon contamination will be part of the revised Preliminary Endangerment Assessment Guidance Manual.

Arsenic Strategies: Determination of Arsenic Remediation - Development of Arsenic Cleanup Goals for Proposed and Existing School Sites 

During the site investigation, arsenic may be identified as a chemical of concern based on comparisons to naturally occurring background concentrations.   Once arsenic has been identified as a chemical of concern, a standard approach is needed to determine if remedial action is warranted and, if so, how to develop appropriate cleanup goals. Comments from stakeholders are welcome and will be posted, and considered in any future revisions of this document. Please send these comments to jhope@dtsc.ca.gov.


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

This guidance document has been rescinded and will be replaced by a revised document following departmental review and comment.

Ambient Metal Concentrations

This guidance document presents several useful principles for defining the local ambient data set, including pooling all data from all impacted sites and locating ambient conditions in the presence of possible contamination.


Background Metals at Los Angeles Unified School Sites - Arsenic

This guidance is intended to supplement the DTSC PEA Guidance Manual (DTSC1994), and provide a uniform and streamlined approach for evaluating background arsenic at LAUSD school sites.


Human Health Risk Assessment Note 1 - Default Human Health Exposure Factors
This note summarizes exposure factors which may be used as default values in human health risk assessments for California hazardous waste sites and permitted facilities.


Human Health Risk Assessment Note 2 - Dioxin-TEQ (Interim)
This note presents a suite of suggested Dioxin-TEQ soil remediation goals that have been developed for consideration at mitigation sites in California for the protection of human health. These goals may be revised in the future, as new scientific information becomes available.


Human Health Risk Assessment Note 3 - DTSC Recommended Methodology for Use of U.S. EPA Regional Screening Levels (RSLs) in Human Health Risk Assessment Process at Hazardous Waste Sites and Permitted Facilities.

The Office of Human and Ecological Risk Assessment has, in the past, used the U.S. EPA Region 9 Preliminary Remediation Goals (PRGs), which included ‘Cal-modified’ PRGs, to facilitate Screening Level Human Health Risk Assessments. The EPA Region 9 PRG values have now been harmonized with risk-based PRGs from other EPA Regional Headquarters, and are called Regional Screening Levels (RSL) which no longer contain the more protective ‘Cal-modified’ PRGs. HHRA Note Number 3 outlines the most recent HERO review of the air and tapwater RSLs (November, 2012) and presents recommended screening values for constituents in which the RSL is not as health protective as the 2004 PRGs, 2004 Cal-modified PRGs, or HERO-calculated risk-based screening levels. A separate link is also provided for download of the associated Table 1 with a listing of alternate soil and tapwater screening values currently recommended in lieu of November 2012 RSLs. New to this iteration of HHRA Note 3 is the incorporation of Phase II HERO recommendations for residential and industrial air screening levels for a subset of VOCs frequently detected at California hazardous waste sites and permitted facilities. For all constituents other than those addressed in Note 3, the DTSC site toxicologist should be consulted prior to using the air RSLs.


Human Health Risk Assessment Note 4 - Screening Level Human Health Risk Assessments

In a memorandum dated October 28, 1994, the Office of Human and Ecological Risk Assessment recommended guidelines for use of the U.S. EPA Region 9 Preliminary Remediation Goals (PRGs) at military sites. Subsequently, the U.S. EPA released Regional Screening Levels (RSLs) to replace the PRGs formerly available from several U.S. EPA Regional offices. In HHRA Note 3, HERO addressed the recommended methodology for use of U.S. EPA RSLs in the human health risk assessment process at DTSC. HHRA Note 4 outlines the current recommended methodology for conducting screening level human health risk assessments, and is an update which replaces our 1994 memorandum.


 

HUMAN HEALTH RISK ASSESSMENT TOOLS

CalTOX

CalTOX is a spreadsheet model that relates the concentration of a chemical in soil to the risk of an adverse health effect for a person living or working on or near the contaminated soil. CalTOX computes site-specific health-based soil clean-up concentrations given target risk levels or human health risks given soil concentrations at the site.


LeadSpread

LeadSpread is a tool for evaluating exposure and the potential for adverse health effects resulting from exposure to lead in the environment.  An updated version of LeadSpread has been developed (LeadSpread 8; 2011) to incorporate the updated CalEPA incremental lead toxicity criterion of 1ug/dL (OEHHA, 2007), as well as ensure that the model is adequately protective of women of child-bearing age.  The link to LeadSpread 7 is maintained for sites outside California being evaluated based on the 10 ug/dL total blood lead criterion.


Cancer Potency Factors and Reference Doses
Cancer Potency Factors and Reference Doses are available from the California Office of Environmental Health Hazard Assessment.


 

VAPOR INTRUSION GUIDANCE AND TOOLS

Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air - Final
This DTSC guidance document provides recommendations on specific technical or scientific issues that may be encountered when evaluating subsurface vapor intrusion to indoor air. It outlines the procedures for evaluating this exposure pathway and provides recommendations on elements that should be included in a facility investigation. It also presents information on indoor air sampling and the engineering approaches for the mitigation of human exposure.


U.S. EPA Johnson & Ettinger Models Modified to Include California Health Criteria

The U.S. Environmental Protection Agency (U.S. EPA) developed a model in 1998 which estimates human health risks from subsurface vapor intrusion into buildings.  This model is based on the work of Johnson and Ettinger, and is revised periodically to incorporate different assumptions about soil properties as well as new human health criteria developed by U.S. EPA.  This model was last revised December 6, 2011 to incorporate new toxicity criteria for trichloroethylene and 1,2,3-trichloropropane.