The mission of the Ecotoxicology Program within the Office of Environmental Health Hazard Assessment (OEHHA) is to advance the science and practice of ecological risk assessment (ERA). We focus on developing tools and technical resources to assess the impacts of chemical, physical, and biological stressors on ecosystems. Our current focus is on aquatic ecosystems.

Our Program was established in 1993 with the goal of applying tools from the developing field of human heath risk assessment to address the risks caused by chemicals on California’s ecosystems. In 1998, the US EPA adopted a set of Guidelines for “evaluating the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more physical, chemical, or biological stressors”. ERA is based on a simple three-step process which includes a) identifying the problem or stressor(s) of concern, b) analyzing the stressors by characterizing their exposure and ecological effects, and c) characterizing risk using a variety of methods. The work of the OEHHA Ecotoxicology Program is currently focused on applying this approach to understanding risks to the State’s aquatic resources.

To inquire about our Program, contact

Reports, Notices, Documents

Jan 20, 2015: Dry Creek Watershed Assessment and Indicator Report
OEHHA is assisting the Dry Creek Conservancy (DCC) and the American Basin Council of Watersheds to gain a better understanding of the stressors in the Dry Creek watershed that have contributed to salmon declines over the past two decades. OEHHA is collecting environmental data and is using the Stressor Identification (ID) method developed by the US Environmental Protection Agency to identify impacts of urbanization and causes of impairment to the health of the watershed.
Mar 16, 2009: Impervious Surface Analysis
Impervious surfaces impact the hydrology, water quality and aquatic and riparian habitat within a watershed.  OEHHA has developed impervious surface coefficients useful in stormwater management runoff analyses, in watershed assessment as an indicator of watershed health, and in land use planning to identify areas of higher or lower imperviousness and opportunities to reduce impervious cover.
Jan 29, 2009: Information on Microcystins
General information and technical resources that provide information to scientists in local public health and natural resource agencies, as well as the public, about microcystins and risks associated with exposure to this family of toxins.
Dec 24, 2008: Toxicity Testing Guidance Documents
Toxicity tests are an important component for assessing the impact of chemicals on ecosystems. Two documents are provided to give an overview of the numerous standardized toxicity test protocols. The soil toxicity guidance document also reviews bioassessment tools and methods that can play a critical role in the ecological risk assessment process.
Jun 7, 2008: Aquatic Resources & Watersheds
The Ecotoxicology Program works with state, local, and non-governmental partners to develop informational literature, tools, and technical resources to promote a better characterization and understanding of the link between land use and aquatic resources protection.