ABSTRACT
Ecotoxicology is about the fate, transport, and effects of chemicals in the environment. The principal challenges are description and prediction, challenges that become much harder when the sources are diffuse, as they are for most regional and global ecological problems. The theory for dealing with fate and transport is much better developed than the theory for dealing with effects. As substances become distributed through the food chain, there will be effects upon organisms; those effects will feed back to modify not only effects on other organisms, but also the flows of material. The fundamental problem is one of extrapolation: from laboratory to field and from the effects on single individuals to the effects on communities and ecosystems. In order to achieve prediction, one needs a mechanistic approach that is tied to individual behavior. The critical problem in ecotoxicology is one of scaling.
