Don’t rush to lay out a beach towel

Ready! Set! Swim? Not yet.

After slicing and dicing the relative risk from pathogens lurking in the surf, there’s one last possible source of germs to consider: beach sand.

Although most research on beach pathogens has focused on microorganisms in the water, researchers are beginning to track bacteria in beach sand as well.

Last summer, UCLA researcher Jennifer Jay reported elevated levels of Escherichia coli and enterococci in sand at two sheltered beaches, Cabrillo Beach in San Pedro and Mother’s Beach in Marina del Rey. These bacteria signal the presence of fecal matter, which carries a host of pathogens.

But scientists are unsure what might cause elevated levels of such bacteria in beach sand or even whether the amounts signal an elevated risk of disease.

“If you look in beach sand, you’re going to find organisms” that form an ecosystem, says Alexandria Boehm, an environmental engineering professor at Stanford University. “We need to determine if the indicator bacteria that we’re finding there are part of that ecosystem or not. If they’re coming from other sources, that’s something to be concerned about.

“We do know,” she says, “that if there’s a direct sewage spill on the sand, there’s presumably a health risk, so you wouldn’t want to swallow that sand or even put your towel down on it.”

The Environmental Protection Agency does not have bacteria standards for sand.

-- Janet Cromley