Genotoxicity Assessment of the Codorus Creek Downstream from P.H. Glatfelter Melissa Hershey Department of Biological Sciences, York College of Pennsylvania Introduction The Codorus Creek is a tributary of the Susquehanna River and is located in York County, Pennsylvania. It is a major source of drinking water for York City and provides ample recreational opportunities for residents. Pollution comes from many sources including agricultural runoff, urban runoff, municipal waste water, failing septic systems, and industrial pollution. Each year, the P.H. Glatfelter paper mill dumps 600,000 pounds of pollutants into Codorus Creek. Like all industrial pollution, these hazardous chemicals have the potential for causing environmental harm and having negative effects on the health of residents near the creek. Careful monitoring and strict regulations prevent industries from causing needless harm on nearby communities. Ames Test The Ames test is used to gather information on the mutagencity of a substance It uses the TA 1535 strain of Salmonella typhimurium which possesses a missense mutation in the gene coding for histidine production Proline is replaced by leucine The mutated strains are more permeable than wild-type bacteria to external chemicals, including potential mutagens. They are also very susceptible to additional mutations because they lack the normal repair mechanisms found in bacteria. Under normal circumstances, TA 1535 will not grow When exposed to a mutagen, the mutant S. typhimurium will revert back to the wild type and will be able to grow and produce its own histidine This test is used by FDA to rapidly and inexpensively test the mutagenicity of various chemicals Methods Results Toxicity None of the samples were found to be toxic The positive control showed a zone of inhibition of 22 mm Ames Test Colonies grew when plated with samples B and C A ring was present around the discs on the nutrient agar and on plates B and C of the minimal agar These colonies had merged and could not be counted Literature Cited Ames, Bruce N Identifying environmental chemicals causing mutations and cancer. Science 204(4393): Magdaleno, A., A. Medelson, A. Fabrizio de Iorio, A. Rendina, and J. Moretton Genotoxicity of leachates from highly polluted lowland river sediments destined for disposal in landfill. Waste Management 28: United States Environmental Protection Agency Envirofacts report: P.H. Glatfelter. Toxics Release Inventory (TRI). Available from: id=17362PHGLT228SO. Accessed 2008 December 1. United States Environmental Protection Agency Integrated Risk Information System: A-Z list of substances. Available from: SubstanceList. Accessed 2008 December 1. York Water Company Comprehensive Water Analysis Available from: Accessed 2009 April 1. Acknowledgements: I would like to thank Dr. Singleton for his guidance and expertise as well as Brandon Seitz for his assistance in collecting field samples Leaching 100 grams crushed and agitated Sampling (n=9) Positive control: Ethidium Bromide Negative Control: Water Nutrient Agar Minimal Agar Top agar with Salmonella typhimurium TA 1535 Sterile disc immersed in sample Ames Test Conclusions 1.Leachates from the sediments of the Codorus Creek are non-toxic 2.A mild mutagen is present in the Codorus Creek The York Water Company found barium compounds, lead compounds, manganese compounds, mercury compounds, and zinc compounds in the water. Lead is listed as a probable carcinogen Other chemicals released by the paper mill were not examined in their study No revertant colonies grew on the negative control Usually there is a background lawn of colonies that grow before using up the available histidine Possibility that the colonies could not establish themselves The number of revertant colonies in the negative control is used to describe a positive result If the colonies could not establish themselves, the data would be misrepresented Colonies became established and did grow on two samples The hypothesis was supported by the data. Hypothesis Mutagens are present in sediment samples taken from sections of Codorus Creek downstream from the P.H. Glatfelter paper mill. Figure 1. Sediment sampling sites