Hey, summer beachgoers: You might think twice about packing those swim fins and snorkels.
A new study by Florida scientists trying to account for pollution suggests that staying out of the water might keep you healthier than going for a dip.
Even in waters with no known impurities, swimmers were more likely to get sick than sunbathers who stayed on the shore, said Jay M. Fleisher, an associate professor of public health at Nova Southeastern University in Fort Lauderdale-Davie.
"We know that waters that have been contaminated with sewage will cause illness," said Fleisher. "We wanted to see whether people were actually getting sick from a beach that had no pollution."
The answer, it turned out, was yes. Fleisher and his crew sent 1,303 adults to Hobie Beach near Miami, a site known for its pristine waters. Half were told to stay dry and other half were sent to swim.
Within a week, it was clear that going in the water took a toll on the bathers. Swimmers were 1.76 times as likely to report stomach troubles; 4.46 times times more likely to report illnesses with fevers, sniffles and sore throats; and 5.91 times more likely to report itching, rashes and other skin woes.
The culprit? Scientists aren't certain, but they suspect enterococcus bacteria, nasty critters normally found in the feces of people and many animals. Health officials typically detect the bacteria in waters sullied by sewage spills, but they were surprised to find it – sometimes in high concentrations – in a beach area without known contamination.
The findings raise troubling questions about public beach water monitoring in the absence of known sewage spills and about whether – and when – it's necessary to warn people about potential health problems. The U.S. Environmental Protection Agency is grappling with the question now, trying to decide whether there's a better way to identify markers of risk, Fleisher said.
In the meantime, Fleisher notes that although swimmers were more likely to become ill than non-swimmers, the number of actual illnesses among people who went in the water was small.
Only about 1 in 100 people developed respiratory illness with fever, and only about 2 in 100 came down with gastrointestinal illness. About 6 in 100 developed skin ailments.
"The individual risk to the bather is fairly low," Fleisher said. "But when you multiply that by the number of people who go on the beach, you could start having a public health problem."
If Fleisher had his way, every beach would be posted with a stoplight-type sign that signals green, yellow or red conditions for healthy water quality.
Barring that, summer swimmers shouldn't be afraid to go in the water, he said. But they might stay healthier if they stick to the shore.
Do you worry about swimming in public waters? Tell us in the comments.