"You take part of the sample and empty it into a sterile vial, and add growth media," said Sherman, who works for the state Division of Marine Fisheries. "That's basically a mixture that's supposed to enhance the growth of bacteria. Then we incubate it at a certain temperature and look to see if there's been growth after 24 hours."
The test determines whether the water contains unsafe levels of enterococci, a fecal bacteria found in the intestines of warm-blooded animals that can indicate the presence of other disease-causing organisms. If the results indicate heightened bacteria levels, state officials will pose a swimming advisory at the affected beach - but because the test takes a full day to complete, those advisories are always based on yesterday's water samples.
"Basically, you've gone to the beach, gotten into the water, there was no sign, and then the next day you hear there's a beach advisory," said Rachel Noble, a professor of environmental biology at the University of North Carolina. "The sample you're hearing about the next morning was taken yesterday when you were swimming."
Noble's aiming to fix the lag using a method devised several years ago that returns water quality results in three to four hours, allowing state officials to post beach advisories on the same day the samples were taken. Using a process known as quantitative polymerase chain reaction, or qPCR, Noble's method also tests for enterococci. Because qPCR uses DNA markers to confirm the presence of the bacteria, results are available in two to three hours.
"That's not perfect. We'd love for it to take five to 10 minutes, but it's an improvement," she said. "Using the rapid method, you can take a sample at 7 or 8 a.m. and the results are posted at the beach by 11, by the time families and most people are putting their towels down."
The rapid testing method is in use at various places across the country, as far north as Racine, Wis., but implementing the system along the North Carolina coast is more complicated.
Water quality officials have been trained to use the process, but uncertain funding makes it difficult to standardize across the state.
"I think we would all like to do it. The problem is the money," said J.D. Potts, director of the state's recreational water quality program. "It costs a lot more, and your lab has to be equipped to run qPCR."
Purchasing the proper equipment and outfitting a lab would cost between $50,000 and $60,000, Noble said, a decrease from several years ago, when it would have run around $100,000.
"The cost of running individual samples is beginning to approach the same cost as the traditional methods, so that's one big advancement," she said. "We're getting to the point where, minus the capital cost, the price of the new and traditional methods are similar."
To implement the rapid method, the state would also need approval from the federal Environmental Protection Agency. At the beginning of this year, EPA recommended that states use rapid testing methods to measure enterococci, but the agency specifically endorses its own, similar process. To petition for statewide usage, officials would most likely have to present EPA with data showing that Noble's method is more user-friendly.
"If somebody takes our method and generates the data themselves and finds it's easier to use, then they'll begin to use it," Noble said. "At this point, adopting the method is really a matter of resources."
Source: StarNews Online