From 1999-2000 the USGS undertook a large survey of pharmaceuticals and other organic contaminates across US waterways. The initial objective of this survey was to gain a general understanding of the range of contamination in the US. Pharmaceuticals and personal care products (PPCPs) contaminating natural waters has continued to grow into an area of concern in the years since that national survey. Recently, the issue is not only with the presence of these PPCPs but also in the concentrations that they may be reaching and the antibacterial resistance that may be occurring in nature. As the source of these contaminants are products utilized by human populations, this research seeks to examine potential relationships that may allow for the prediction of PPCP concentration based upon human population density data. Before committing the time and resources to a large sampling project, this research project will instead attempt to harness existing the data from the aforementioned USGS survey combined with US census data in a GIS to determine if any predictive trends are present. Analysis of the data will take place at multiple spatial scales and may also consider additional factors such as land use and income levels.
Results/Conclusions
Preliminary results have found limited relationships between some of the concentrations of the 30 measured PPCPs with human populations at the lowest calculated scale, a 5 km radius. The majority of the PPCPs displayed a positive relationship between increased concentration and population size at multiple scales, and a correlation analysis is currently ongoing to determine the significance of these relationships. Further analysis will verify the findings that the 5 km radius samples appear to be the most reliable predictor of PPCP concentration, while an increase to a 10 km radius up to the county level seems to decrease the predictive capabilities. These findings would seem to indicate that population size alone does not influence the concentration of PPCPs, however the addition of more recent data from other studies may be necessary for a more definitive conclusion.