Utility of Pharmaceuticals and Other Emerging Contaminants as Chemical Indicators of Human Fecal Contamination
To determine if the chemicals present in wastewater effluent (including pharmaceuticals) can be used as indicators of human fecal contamination. Even if there is not sufficient evidence to conclude that a chemical can serve as an independent indicator, chemicals may be able to be used in conjunction with microbial indicators to establish the source of fecal pollution.
This project is a companion to the USEPA's and USGS' collaboration: "Occurrence, Transport, and Fate of Pharmaceuticals and Other Emerging Contaminants Present in Wastewater." The wastewater treatment plant (WWTP) sampling in that study gave information on the occurrence and persistence of wastewater chemicals. To determine if there was a correlation between the chemicals and pathogens that caused negative health impacts, samples were collected as part of the National Epidemiological and Environmental Assessment of Recreational (NEEAR) Water Study. The samples were analyzed for 87 chemicals using two different analytical methods: (1) continuous liquid/liquid extraction followed by gas chromatography/ mass spectrometry (GC/MS) analysis for 66 common wastewater chemicals; (2) solid phase extraction (SPE) followed by liquid chromatography/mass spectrometry positive-ion electrospray (LC/MS-ESI(+)) analysis for 21 pharmaceuticals. To date, five beaches (4 freshwater, 1 marine) have been studied; a sixth beach (marine) will be sampled in 2007.
In the WWTP study, the concentrations of the microbial indicators followed different patterns than the chemicals. The chemical concentrations were typically low in the upstream sample, reached a maximum in the effluent, and then decreased with increasing distance downstream. Conversely, the microbial indicator concentrations were often high in the upstream sample, lower in the effluent, and then increased downstream. This data illustrates one of the weaknesses of microbial indicators - the bacterial concentrations do not reflect wastewater inputs.
In the NEEAR samples, 54 of the 87 compounds were detected at least once; ten chemicals were detected at least once at all five beaches. However, the beaches were different from one another in terms of the numbers of chemicals, and the frequency of detections. The statistical correlation of the chemical detections to the epidemiological data is currently being performed by personnel from USEPA's National Health and Environmental Effects Research Laboratory.
The currently used indicators for drinking water and recreational water are not human specific. Chemical indicators have the potential of reducing the analysis times and providing source discrimination. If suitable chemical indicators can be identified, beach and drinking water treatment plant managers will have an additional tool to monitor water quality and ensure public health safety.
Susan Glassmeyer at firstname.lastname@example.org