Two wildlife exposure models to assess impacts at the individual and population levels and the efficacy of remedial actions

We present two models to assess wildlife exposure to chemical stressors in soils and food. The models incorporate information on the magnitude and spatial distribution of chemicals in soil, as well as the foraging area and movement of wildlife. The models assume wildlife are exposed to chemicals in contaminated food such as soil invertebrates, and that soil invertebrates bioaccumulate the chemicals from contaminated soil. The models compare an animal's exposure to a variety of measurement end points (e.g., mortality, reproductive success, and developmental effects), expressed as ''soil effects levels.'' The first model, the ''Average Concentration with Area Curve'' exposure model, is a simple graphical tool that evaluates the potential for effects to individuals that forage within the most contaminated areas of a site. The ''Population Effects Foraging'' (PEF) model evaluates the number of individuals within a local population that may be affected at a site. The PEF model limits an individual's movement based on the species' foraging area and site-specific information such as available habitat. We illustrate the models using a hypothetical hazardous waste site to demonstrate the effect of contaminant distribution on baseline conditions and remedial actions. Risk assessors can adapt the models for use with a variety of hazardous waste sites, wildlife species, and chemical stressors. Graphical presentations of the results emphasize the importance of risk presentation in conveying uncertainty to risk managers.