Post by jeff on Dec 24, 2006 11:36:37 GMT -5
UNION-TRIBUNE
December 23, 2006
New research shows that surfers and other beachgoers should take beach contamination warnings seriously, especially if they're anywhere near the U.S.-Mexico border.
A two-year study by San Diego State University professor Rick Gersberg reaffirmed the accuracy of contamination warnings posted by county officials at the mouth of the Tijuana River and in Imperial Beach.
Gersberg's use of high-tech genetic testing to detect water-borne viruses also demonstrated the effectiveness of that method and bolsters the case for its use in the future by public health agencies.
“This shows the promise of genetic testing for the whole diversity of pathogens in the water” that are harmful to humans, Gersberg said.
Public health officials nationwide monitor water quality by testing for bacteria, a process that takes from 24 to 72 hours to produce results. While most of these bacteria are harmless, the Environmental Protection Agency considers them reliable tracers for viruses and other pathogens that actually cause human illness.
Gersberg's study examined 20 water samples taken from 2003 to 2005 at the mouth of the Tijuana River and in the surf zone at the Imperial Beach pier.
Samples taken during dry weather confirmed the water was safe.
The opposite was true for coastal waters during or immediately after a rain storm.
Using a method known as polymerase chain reaction or PCR – a test that yields results in a few hours – Gersberg found Hepatitis A and other viruses at the same beaches posted by the county based on bacteria readings.
His research is significant because bacteria-based water testing is increasingly criticized as too slow and prone to yielding false positive results. For instance, a previous study found that many high-bacteria readings at Mission Bay were the result of fecal coliform bacteria from bird droppings, which are unlikely to cause illness in humans.
Gersberg said he wasn't surprised to find Hepatitis A and other viruses because the source of the contamination at South Bay beaches is urban runoff from the Tijuana region, where 25 percent to 30 percent of homes and businesses are not connected to a sewer system.
Jeff Knox, who has been surfing near the Tijuana River for five decades, said he doubted the new scientific findings would trigger any significant remedial action by government officials.
“I don't think the 'powers that be' are too concerned about a bunch of surfers,” Knox said.
Nonetheless, he said he appreciated any effort that focuses attention on the border pollution problem.
“Just about everyone who surfs Imperial Beach on a regular basis has become ill,” he said. “We have long suspected viral contamination of our coastal waters, but we haven't seen any studies on it until now.”
Imperial Beach Councilwoman Patricia McCoy said she hopes the research will build confidence among public health officials in the genetic-based water testing. Because results can be obtained in a few hours, the high-tech genetic testing can shorten the time a beach is posted for contamination.
“I applaud anything that will keep our beaches open sooner,” McCoy said.
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Terry Rodgers: (619) 542-4566; terry.rodgers@uniontrib.com
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December 23, 2006
New research shows that surfers and other beachgoers should take beach contamination warnings seriously, especially if they're anywhere near the U.S.-Mexico border.
A two-year study by San Diego State University professor Rick Gersberg reaffirmed the accuracy of contamination warnings posted by county officials at the mouth of the Tijuana River and in Imperial Beach.
Gersberg's use of high-tech genetic testing to detect water-borne viruses also demonstrated the effectiveness of that method and bolsters the case for its use in the future by public health agencies.
“This shows the promise of genetic testing for the whole diversity of pathogens in the water” that are harmful to humans, Gersberg said.
Public health officials nationwide monitor water quality by testing for bacteria, a process that takes from 24 to 72 hours to produce results. While most of these bacteria are harmless, the Environmental Protection Agency considers them reliable tracers for viruses and other pathogens that actually cause human illness.
Gersberg's study examined 20 water samples taken from 2003 to 2005 at the mouth of the Tijuana River and in the surf zone at the Imperial Beach pier.
Samples taken during dry weather confirmed the water was safe.
The opposite was true for coastal waters during or immediately after a rain storm.
Using a method known as polymerase chain reaction or PCR – a test that yields results in a few hours – Gersberg found Hepatitis A and other viruses at the same beaches posted by the county based on bacteria readings.
His research is significant because bacteria-based water testing is increasingly criticized as too slow and prone to yielding false positive results. For instance, a previous study found that many high-bacteria readings at Mission Bay were the result of fecal coliform bacteria from bird droppings, which are unlikely to cause illness in humans.
Gersberg said he wasn't surprised to find Hepatitis A and other viruses because the source of the contamination at South Bay beaches is urban runoff from the Tijuana region, where 25 percent to 30 percent of homes and businesses are not connected to a sewer system.
Jeff Knox, who has been surfing near the Tijuana River for five decades, said he doubted the new scientific findings would trigger any significant remedial action by government officials.
“I don't think the 'powers that be' are too concerned about a bunch of surfers,” Knox said.
Nonetheless, he said he appreciated any effort that focuses attention on the border pollution problem.
“Just about everyone who surfs Imperial Beach on a regular basis has become ill,” he said. “We have long suspected viral contamination of our coastal waters, but we haven't seen any studies on it until now.”
Imperial Beach Councilwoman Patricia McCoy said she hopes the research will build confidence among public health officials in the genetic-based water testing. Because results can be obtained in a few hours, the high-tech genetic testing can shorten the time a beach is posted for contamination.
“I applaud anything that will keep our beaches open sooner,” McCoy said.
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Terry Rodgers: (619) 542-4566; terry.rodgers@uniontrib.com
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