I suggest that we look at global distribution diagrams and global concentrations and accumulation models of chemicals as it pertains to risk. I suppose I am kind of biased to the topic.
Think Globally; Act Locally.. Thus said the bumper sticker. In our work so far, we have dealt with local sources of pollution. Usually the nature of the source was such that a mile or two away, you could consider it a "point source." Then we do "fate and transport" calculations to determine the exposure of individuals some time and distance away. Then we do a dose-response analysis of those individuals and we are done. This fits our (my) typical situation where somebody must pay to clean up some contamination. On the global level, pollution might come from anywhere, get moved to a location by the wind and weather, and accumulate up the foodchain, bioaccumulate. The risk assessment principles still apply, you need to do an exposure analysis and then a dose-response analysis. The chief difference is that you do not have a point source to model from, but rather assume the exposed individuals are more or less exposed to a uniform concentration of contaminant. You can look at the subsistence foods articles or here is something on mercury in the environment Or lead. Or persistent organic pollutants.
Module 13 Index