Measuring Sources of Endocrine Disrupting Compounds in North Carolina Waterways: A GIS-Based Sampling Approach for Studies on Intersex Fish

The presence of endocrine disrupting compounds (EDCs), particularly estrogens and estrogen mimics, has drawn public concern across the globe.  Evidence linking EDCs with fish reproductive impairment (e.g., feminized males) indicate that waters impacted by EDCs may lead to fish population declines. However, one of the many troubling aspects of EDCs is that we currently lack a clear understanding of the extent and distribution of EDCs in surface waters and their relation to potential sources (e.g. waste water treatment plants, confined animal feeding operations, land application of municipal waste).  Therefore, the objective of our study was to identify locations and examine the impact of potential EDC sources in North Carolina water bodies using a GIS mapping and analysis approach.  Data from the National Pollutant Discharge Elimination System, Environmental Protection Agency, and North Carolina Department of Environmental and Natural Resources were used to create point and non-point source maps depicting the relative and cumulative contribution of potential sources of EDCs (within 12-digit hydrological unit codes, HUCs) to North Carolina surface waters.  Water (from 33 sites) and fish gonad tissue (from 20 sites) was also collected to validate the predictive results of our GIS analysis.  Preliminary results suggest that estrogenicity measured in a single grab sample of water, did not match GIS predictions.  We expect the occurrence of feminized males, however, will reflect map predictions because this endpoint represents the impact of cumulative, long-term exposure.  This study provides information on the extent and distribution of EDCs in surface waters, an important first step towards developing a management strategy and determines the relative contribution of EDCs from different sources.