Exposure to dioxins, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) has been related to alterations in cellular and humoral immune responses in both adaptive and innate immune systems of most animal species. These compounds share a common signaling mechanism to exert their effects on cells of the immune system, which includes the aryl-hydrocarbon receptor (AhR) and the AhR nuclear translocator (ARN). Recently, the interference of AhR-ARNT with the nuclear factor (NF)-kappaB signaling pathway has been proposed as a critical event in the adverse effects on the immune system. Studies on the effects of these AhR-ARNT-related toxicants on the immune system of higher and lower phylum animals and knowledge of intracellular mechanisms of toxicity may contribute to development of biomarkers of ecotoxicant exposure and effects. Biomarkers of this kind allow sampling over extended geographic areas, in several sentinel species, including wildlife animals, and facilitate the building of risk models and risk maps of environmentally induced diseases. On the basis of location, biomarker sampled data obtained through evaluation of ecotoxicant exposure and effects on the immune system in sentinel species can be further integrated and analyzed together with other sources of environmental geographic information, or human population health data, by means of geographic information systems (GIS). The spatial analysis capability of GIS can help to evaluate the complex relationships of overlaid information and to identify areas with high risk indices or "hot spots." This integrative approach can be useful in studies contributing to support environmental and health-related policies and regulations.