Integration of human health and ecological risk assessment.

Health risk assessments and ecological risk assessments of contaminated environments are typically conducted by different groups working largely independendy. This results in inefficiencies and, more importantly, in assessments that are less defensible than would otherwise be possible. I would like to argue for integration of health and ecological risk assessment by presenting some of the issues that have arisen at their interface. Although most health risk assessors do not perceive ecological risks to be relevant to their analyses, the public often makes the connection. As a result, health risk assessors may be caught off guard in public meetings when the public asks how health risks can be described as insignificant when the fish have tumors and lesions or fish-eating birds are estimated to have significant reproductive decrements. Interactions with the ecological risk assessors would prepare them for this response. In many cases, there is no actual contradiction because, for a variety of reasons , nonhuman organisms are much more exposed or more sensitive than humans (1). In other cases, the ecological risk assessment may point to health issues that have not be adequately considered. Conceptual models are representations of the means by which effects may be imposed on an endpoint due to the operation of a source. For health risk assessments, conceptual models include pathways of human exposure to released contaminants. Ecological conceptual models include analogous exposures as well as routes of exposure that are not appropriate to humans, such as respiring water, and indirect effects such as loss of food resources or habitat structure. Joint development of these models might lead to a more complete understanding of processes that occur at a site. In addition, it would ensure that the differences between the models are well understood and justified. For example, dermal exposure is a potentially important route for humans, but the equivalent route for wildlife is preening of the plumage or grooming of the fur, resulting in an oral exposure. Because of their training and inclination, ecological risk assessors are typically more site focused than health risk assessors and they are less trusting of standard models and default parameters. For example, it is not uncommon for ecological risk assessors to measure uptake of contaminants at a site by plants or other components of the food web, while health risk assessors use default uptake factors that differ by orders of magnitude from the site-specific values. As requirements for the …