Study finds South Florida beach sand tainted with E. coli, other bacteria

South Florida Sun-Sentinel
Published Monday, September 10, 2007

FORT LAUDERDALE -- From afar, South Florida's golden-sand coastline might look postcard-perfect, but a new two-year study of beaches in Fort Lauderdale, Hollywood and Miami found sand tainted with E. coli and other potentially harmful bacteria in levels 100 to 1,000 times greater than what's in the water lapping at the shore.

So, is beach sand making us sick? The best research so far says, possibly.

Scientists know E. coli can harm us. They're finding it and other fecal bacteria in large quantities on some beaches. Logic tells them that we should be falling ill. But scientists have never found a direct link, and the few studies that have been completed have generated more questions than answers.

Even the authors of the new study of South Florida beaches are divided about the risk of beach sand.

"We believe the risk is there, whether or not there have been documented problems," said Florida Atlantic University scientist Nwadiuto Esiobu.

Not necessarily, says Nova Southeastern University scientist Donald McCorquodale. He suspects beach bacteria are largely harmless and have lost their capability to make someone sick.

That two experts can look at the same data and come to different conclusions illustrates how complicated this area of study is, scientists say, and both sides say more study is needed before anyone really understands what's at stake.

"Just because you're finding high levels of bacteria doesn't mean there's a health risk. And it doesn't mean it's safe either," said Timothy Wade, an epidemiologist with the Florida Department of Environmental Protection. "The truth is we simply don't know."

After years of trying to understand the risks of swimming in contaminated water, scientists have only recently begun to look at whether beach sand poses a similar threat.

The South Florida study, published last month in the peer-reviewed scientific journal Marine Pollution Bulletin, is among the first of its kind to look at local beaches but limited its research to Broward and Miami-Dade counties. But it comes on the heels of other studies, on public beaches in Southern California and around the Great Lakes region, that found similarly high levels of E. coli and other types of fecal bacteria, suggesting the problem isn't confined to one area.

Experts say this research could ultimately have far-reaching effects in South Florida -- where sand and surf help contribute billions of dollars to the local economy every year -- and places like it where coastlines play a critical role in tourism.

"There's a problem here that we need to take a look at," said Walter McLeod, president of the nonprofit Clean Beaches Council in Washington, D.C. "Water has always been seen as the biggest health risk. But you look at the levels being found on sand and it's shocking."

A 2005 report by the Clean Beaches Council highlighted these growing concerns, showing bacteria in sand had far surpassed the potentially harmful levels known to exist in the ocean. Researchers at UCLA and Stanford University took it a step further in 2006, co-authoring a study that estimated up to 1.5 million people a year are getting sick from bacteria on Southern California's beaches. Like in Florida, the California study found bacteria levels up to 1,000 times higher than in the ocean.

But like a lot of scientific explorations, there are no clear answers what this means. Swimming in water loaded with bacteria poses a risk because of how easily water ends up in the mouth, eyes and nose, experts say. Sand can find its way there too, but in much smaller amounts.

Scientists wonder: Are the bacteria counts in sand so high that even a small amount is risky? Or do bacteria behave so differently in sand that even the most frequent beachgoers have nothing to worry about?

And then there's this, which might be the most difficult question of all: Would we even know if sand was making us sick?

Think about it. When we come down with an upset stomach or a sore throat after a day at the beach, where do we point the finger? A sick child? That macaroni salad that sat too long in the sun? At what point do we think about the sand? Ever?

"That's the real challenge in all of this," said Helen Solo-Gabriele, an environmental engineer at the University of Miami who led a 2001 study of two beaches in Miami-Dade County. That study looked at bacteria levels but did not address the health questions.

"There are so many complicated factors why somebody might become sick. You can't just look at one source," Solo-Gabriele said.

What concerns scientists is not only the amount of bacteria turning up on beaches but also the amount of time beachgoers typically spend on the sand with very little clothing.

But there are other concerns lurking out of view, experts said. High levels of fecal bacteria can suggest traces of even more harmful pollutants such as salmonella that were not tested for.

"High levels (of fecal bacteria) are biological indicators and when they're extremely high you know you have a problem," said John Pisani, chief of microbiology at Micrim Labs in Fort Lauderdale. "You have to wonder what else might be there."

Scientists point to many reasons why fecal bacteria accumulate on beaches: Storms wash phosphorus- and bacteria-rich water from cities and farms into canals, where it winds toward the ocean before coming back ashore. Birds and dogs use the sand as their toilet. Garbage and litter pile up. And beachgoers typically shed their own bacteria in the abrasive sand.

Esiobu said researchers also considered another possible factor: Every day 420 million gallons of treated sewage is pumped into the ocean from six regional water processing plants in Palm Beach, Broward and Miami-Dade counties. The Florida Department of Environmental Protection, which licenses this disposal method, has never studied its impact on beach sand. Neither has the Florida Department of Health, which tests the ocean every week for unsafe bacteria levels.

Researchers hope more study provides a clear understanding of what these high beach bacteria levels mean.

"Water was always seen as posing the biggest health risk," the Clean Beaches Council's McLeod said. "But the numbers on beaches are so high that we need to start paying attention."

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