Conclusion
In summary, we have reviewed the recent literature on the use of GIS in exposure assessment for environmental epidemiology and described principles and applications of three core scientific disciplines needed, in our opinion, to successfully implement such studies: geospatial science, environmental science, and epidemiology. This by no means preempts the need for other scientific disciplines in the execution of such studies. In particular, statistics is a core science that would benefit every study, and other disciplines should be included based on the focus and objective of the study. Based on our findings, we offer the following conclusions:
The use of GIS in exposure assessment for environmental epidemiology studies is not only feasible but can enhance the understanding of the association between contaminants in our environment and disease.
A good environmental epidemiology study design should aim to maximize exposure contrasts and thus study population selection should be based on an a priori conception of the geographic distribution of exposures in the study area whenever possible (even if crude). For this purpose, GIS-based exposure mapping can be useful, given that geo-referenced data are available at a relevant scale.
It is preferable in an environmental epidemiology study to estimate and validate levels of the agent (contaminant) of interest in the environment of the study population. These levels are the basis for estimating personal exposure and dose and for classifying exposure across a study population. GIS and related technology (source/receptor model; environmental simulation models) can improve accuracy in identifying source and route of potential exposure in a study area and in estimating levels of target contaminants.
When environmental levels of the agent (contaminant) of interest in the environment of the study population cannot be measured or accurately predicted, GIS provide the optimal technology for using proximity to contaminant source in an environmental epidemiology study. It is well established as a viable tool in ecologic study design.
GIS and related technologies such as the GPS are useful for providing precise locations of study participant residences and other stationary data. Research is needed on how to integrate this use of the technology with epidemiologic questionnaire and environmental data for exposure assessment.
Environmental epidemiology studies require interdisciplinary expertise and adherence to the fundamental principles of geospatial science, environmental science, and epidemiology.