Office of Human and Ecological Risk Overview

The Human and Ecological Risk Division (HERD) provides DTSC program staff with world-class technical assistance and training on chemical toxicity and human health, and ecological risk assessment. In addition, research presentations written by HERD staff are often delivered at international professional society conferences.

Human Health Risk

Human health risk assessment involves examining issues related to specific contaminants, including environmental fate and transport, and exposure assessment. In addition, the toxicity parameters of contaminants are evaluated to make sure that the latest scientific knowledge is used in evaluating potential toxicity. These evaluations are based on sound scientific knowledge and fact, and comply with Department and U.S. EPA risk assessment guidance, and policy. At sites involving remedial action, risk assessment is used to determine the nature and extent of remedial activities, such as establishing preliminary cleanup goals.

Ecological Risk

Ecological Risk Assessment considers the potential adverse effects of chemicals on the biological communities. There are more species native to California than any other area in North America of equal size. Among animals as a whole (including insects and other invertebrates), at least 50 percent of the species and sub-species are found only in California. DTSC is the designated co-trustee for natural resources, along with the California Department of Fish and Game, under the Comprehensive Environmental Resource Protection Act (Superfund).

DTSC and HERD operate in cooperation with other regulatory agencies and trustees to advise, review and approve investigations regarding natural resources. HERD eco-toxicologists focus on the protection of numerous habitats, from wetlands and coastal areas to the high desert HERD's objective is to protect the state's ecological resources by promoting well-designed and well-executed ecological risk assessments. HERD eco-toxicologists have been at the forefront, first by issuing "Guidance for Ecological Risk Assessment at Hazardous Waste Sites and Permitted Facilities (1996) and second by continual updates to guidance in the form of "EcoNOTEs".

The Federal Facilities Section of HERD works closely with the department's Office of Military Facilities to oversee toxicology and risk assessment at current and former defense facilities in California. Each base may have several hundred individual toxic waste release sites, often with a complex mixture of toxic chemicals in soil and groundwater. These sites also present a multifaceted regulatory environment involving State, Federal and local re-use agencies. HERD toxicologists play a key role, translating between the different risk assessment, risk management and regulatory cultures. HERD's eco-toxicologists are important players in military cleanups since the bases contain large areas of open habitat; much of it in fragile coastal or desert environments.

Military Base Disposal Site

The Schools Section provides site-specific exposure and health risk assessments, site characterization, and fate and transport modeling for proposed and existing schools in California, ensuring protection of some of the state's most sensitive populations.

HERS toxicologists communicate their findings on health risks directly to the public, both in written materials and at community meetings, and when necessary, participate in efforts to clean up school sites. The HERS Schools Unit has developed guidance and technical memorandum to assist others in the technical and scientific assessment of school properties.

GIS and Risk Communication

HERD scientific staff provide DTSC with Geographic Information Systems analytical and visual materials for public presentations. Three dimensional contaminate plume models are developed that incorporate aerial photographs and satellite imagery. Using regional data, we are able to combine site related environmental data with demographic and socio-economic data to better understand and communicate cumulative risk within limited geographic areas.