Using Today's Data to Close the Beach Today!
Quantitative Polymerase Chain Reaction (QPCR) rapid beach closings tool
Recreational beaches are an important economic and aesthetic asset to communities, states and the nation as a whole. Considerable resources are expended each year in the measurement of fecal indicator bacteria concentrations in the water at these beaches to determine whether these waters are safe for public use. These measurements are presently performed by culture-based methods such as membrane filtration that require at least 24 hr before results are obtained. As a result, these methods often may not allow notification of potential health risks to swimmers until after exposures have occurred. Several molecular microbial analysis technologies have the capability of circumventing this deficiency by providing results in shorter time periods. One particularly rapid technology is the quantitative polymerase chain reaction (QPCR). Water analyses using this technology can provide results in approximately 2 hours. This technology has now been adapted for the measurement of the EPA-recommended fecal indicator organisms, Eschericia coli and Enterococcus, in surface water samples. In the summer of 2003, studies were initiated by the USEPA, Office of Research and Development, at two Great Lakes beaches, to determine the correlation between QPCR and EPA Method 1600 (membrane filtration) measurements of enterococci in water samples and swimmer illness rates. Positive correlations were observed between illness rates and the results of both methods and continuing evaluations are being performed in 2004. This presentation will provide an overview of the principles of the QPCR method, describe its application for beach water quality analysis and provide current data on the relationship between results obtained by this method and membrane filtration.
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.