Exposure Factor and Toxicity Data for California Wildlife: Data Availability and Sources of Uncertainty for Ecological Risk Assessments

Abstract

Data needs for terrestrial ecological risk assessments are generally diverse, consisting of a large array of chemicaland wildlife species-specific information for exposure and effects evaluation. Normalizing factors (e.g., body weight and metabolic rate), contact rates (e.g., ingestion rates, dietary composition and inhalation rates), population dynamics information (e.g., home range size) and seasonal activity descriptions (e.g., migration patterns) for mammalian, avian, amphibian and reptile species of concern are often required for exposure estimation (U.S. EPA, 1993). Toxicity data needs for these species vary with the assessment endpoints of the ecological risk assessment but may include individual-, populationor community level endpoints (U.S. EPA, 1998). While new site-specific data may be collected for an ecological risk assessment, initial phases of the assessment are likely to utilize existing data from the scientific literature. Databases of ecological exposure and effects information are available but they generally address a limited range of information or number of species. For example, the U.S. Environmental Protection Agency has compiled exposure factor data for thirty-four mammals, birds, reptiles and amphibians (U.S. EPA, 1993). In order to address ecological risk assessment data needs in California, we developed Cal/Ecotox, a database of exposure factors and toxicity data for sixtytwo species of California mammals, birds, reptiles and amphibians (see http://www.oehha.ca.gov). One of the key difficulties encountered in ecological risk assessments is the lack of exposure factor and toxicity data for many wildlife species (SETAC, 1987). Extrapolation of existing data provides an approach to overcome these data gaps but this method contributes uncertainty to the ecological risk assessment (Warren-Hicks and Moore, 1998). In this paper, we describe Cal/Ecotox and provide a survey of data currently in the database to assist in the identification of data gaps and potential sources of uncertainty for ecological risk assessment. Identification of these data gaps may contribute to prioritizing current research needs in ecological risk assessment.