Academic journal article Environmental Health Perspectives

Using Geographic Information Systems for Exposure Assessment in Environmental Epidemiology Studies

Academic journal article Environmental Health Perspectives

Using Geographic Information Systems for Exposure Assessment in Environmental Epidemiology Studies

Article excerpt

Geographic information systems (GIS) are being used with increasing frequency in environmental epidemiology studies. Reported applications include locating the study population by geocoding addresses (assigning mapping coordinates), using proximity analysis of contaminant source as a surrogate for exposure, and integrating environmental monitoring data into the analysis of the health outcomes. Although most of these studies have been ecologic in design, some have used GIS in estimating environmental levels of a contaminant at the individual level and to design exposure metrics for use in epidemiologic studies. In this article we discuss fundamentals of three scientific disciplines instrumental to using GIS in exposure assessment for epidemiologic studies: geospatial science, environmental science, and epidemiology. We also explore how a GIS can be used to accomplish several steps in the exposure assessment process. These steps include defining the study population, identifying source and potential routes of exposure, estimating environmental levels of target contaminants, and estimating personal exposures. We present and discuss examples for the first three steps. We discuss potential use of GIS and global positioning systems (GPS) in the last step. On the basis of our findings, we conclude that 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. Key words: environmental epidemiology, exposure assessment, geographic information systems. Environ Health Perspect 112:1007-1015 (2004). doi:10.1289/ehp.6738 available via http://dx.doi.org/[Online 15 April 2004]

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Environmental epidemiology is an area of epidemiology concerned with the study of associations between environmental exposures and health outcomes, with the purpose of further understanding the etiology of disease. The term "environment" implies a spatial context. Thus, the study of interactions between humans and their environment requires spatial information and analysis. Geographic information system (GIS) software allows environmental and epidemiologic data to be stored, analyzed, and displayed spadally. The logical structure and functionality of a GIS are shown in Figure 1 (Falbo et al. 1991). Data collection can be accomplished by importing tabular or digital data that are referenced with map coordinates defining their geographic position. The data are entered into a database where they are stored as a map with a specified theme (termed "data layer"). Tabular (attribute) data corresponding to the theme can be stored with each data layer. Analytical functions within the software can be used to process and manipulate both map and attribute data through linkages established within the GIS. Two types of output are common: tabular (summary data, statistics, reports) and cartographic (maps, map files, and map overlays). Several publications describe the structure and functionality of a GIS more thoroughly (Chrisman 2002; DeMers 2000). Vine et al. (1997) provide an overview of the use of specific functions in GIS software that could be useful in environmental epidemiologic research. Beyea and Hatch (1999) provide an in-depth discussion of geographic modeling for exposure assessment in environmental epidemiology, as well as an extensive literature review. Briggs and Elliot (1995) provide a review of spatial analysis and mapping in environmental health.

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GIS have been used at different levels of sophistication in environmental epidemiology studies. These uses range from simply locating the study population by geocoding addresses (assigning mapping coordinates) to using proximity to contaminant source as a surrogate for exposure (Bell et al. 2001; Comba et al. 2003; Langholz et al. 2002; Xiang et al. 2000) to integrating environmental monitoring data into the analysis of the health outcomes (Floret et al. …

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