May 25, 2007 -- Beach sand and surf may harbor E. coli bacteria, and those bacteria could shut down some beaches, a new study shows.
The researchers included Michael Sadowsky, PhD, a professor in the University of Minnesota's department of soil, water, and climate.
They studied water and sand from the Duluth Boat Club Beach in Duluth, Minn., on the banks of Lake Superior. That beach is "frequently closed in summer due to high counts of [E. coli] bacteria," write the researchers.
During 2004 and 2005, the researchers took samples of the beach's sand and surf. They found more than 3,500 strains of E. coli bacteria.
Only one of those strains might be a health threat to humans, Sadowsky's team notes.
Leading sources of the bacteria appear to be a nearby wastewater treatment plant and migrating waterfowl such as terns, geese, and gulls in the summer and fall.
Waterfowl may also carry other bacteria, such as salmonella and campylobacter bacteria, according to Sadowsky and colleagues. But they didn't study those bacteria.
"The potential health risks associated with waterfowl-borne bacteria found at beaches needs to be investigated in the future," the researchers write.
Their findings appear in the journal Environmental Science & Technology.
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