Paradigms for ecological risk assessment.

Ecological risk assessment developed from the convergence of human health risk assessment, ecology, and ecotoxicology to provide data for environmental management and decision making. There has been an emphasis on using the health risk paradigm. However, ecological systems are much more complex than the single-species, single-lifetime approach used in human health risk assessment; hence several modifications are necessary, as ecological risk assessment evolves for particular uses. The advancement of ecological risk assessment is particularly timely, given competing considerations for cleanup of a variety of hazardous-waste sites, including the huge Department of Defense and Department of Energy sites, as well as the 1000+ Superfund sites. Sufficient resources are not available to clean up all sites completely, much less at the same time. Some sites pose no current identifiable risk to human receptors, but may be unusable for human habitation. Where human receptors are not the targets, ecological risk assessment can be used not only to evaluate the risks to ecosystems, but to help determine the degree of cleanup required to restore degraded environments to functioning ecosystems that provide valuable ecological services, and to rank sites for possible cleanup.