Downstream cancer mortality: Using geospatial techniques to examine point source pollution impacts within the Ohio River watershed

Background. Industrial and agricultural processes result in the release of harmful contaminants into ground and surface water, including contaminants that are established risks for a variety of cancers. The study of watersheds has provided insight into the potential impact contaminants can have in areas far removed from their point source.

Methods. Merging epidemiological and geospatial techniques, cancer mortality is assessed in nonindustrial areas downstream from potential contaminant point sources within the Ohio River basin, a watershed comprising roughly 500 counties throughout 13 US States. Cancer data were obtained from the CDC public files, expressed as county-level, age-adjusted mortality per 100,000 for the years 1999-2005. Point pollution sources were obtained from the EPA Toxic Release Inventory and the eGRID database on power point locations. Watershed data and maps were obtained from the Natural Resources Conservation Service and the National Hydrography Dataset, respectively. Comparisons were made to demographically and geographically similar counties in the watershed absent of significant upstream contaminant sources. Statistical analyses controlled for other risk factors for cancer incidence (e.g., smoking rates, poverty rates, physician supply, etc.) using data from the US Census, the Area Resource File and other sources.

Results and Discussion. Database development is currently underway as part of a larger study funded by the Health Resources Services Administration. Data will be analyzed using spatial and quantitative modeling and results will be developed over the spring and summer of 2009. Results will be evaluated to determine associations between point pollution sources, watershed processes, and human health outcomes.