Assessment of exposure and effects associated with polycyclic aromatic hydrocarbon contamination in south Chattanooga, Tennessee

The southern part of Chattanooga, TN has been subject to dumping of industrial waste for over 100 years. Chattanooga Creek flows north through this area to the Tennessee River. The dumping of coal tar and other industrial waste in this area has lead to the contamination of Chattanooga Creek and soil of the surrounding floodplains. Many polycyclic aromatic hydrocarbons (PAHs) are found in these areas, specifically the 16 PAHs the EPA and ATSDR consider to be priority pollutants. The close proximity of residents to contaminated sites in southern Chattanooga initiated an assessment of the potential human health risks. The research presented herein is part of this larger assessment. The results of a concomitant study indicated significantly higher levels of soil PAHs in South Chattanooga as compared to a reference site in northern Georgia. An assessment of bioavailability and exposure was conducted using indigenous small mammals (Peromyscus gossypinus). This assessment showed that PAHs are bioavailable to small mammals and they are being exposed to these contaminants. The present study examined PAH-DNA adduct formation as an indication of specific PAH exposure in small mammals inhabiting contaminated and reference sites. Preliminary results suggest more BPDE-DNA adducts are present in mice from the reference site population than the contaminated site, possibly indicating increased detoxification of PAHs or repair of DNA damage in mice from the contaminated site. Further validation of this data is warranted. Potential population-level effects of these PAHs were also measured by evaluating changes in genetic diversity. The results of the genetic diversity study show a general trend of homogeneity in the contaminated populations. It also shows that in terms of gene differentiation, the populations in the contaminated sites were significantly different from the reference populations. Overall, the present study found indications of higher level effects of contamination in small mammals, but further research is needed to complete this health risk assessment.