Next time you're packing your towel and sunscreen for a trip to the beach, you may want to check water quality reports, too.
Illness-causing bacteria are common in the nation's beaches, from marine areas to the Great Lakes.
Check water reports before you swim.
Practice good hygiene during and after visiting the beach.
You might not be sick of the beach yet, but the beach might be making you sick, suggest two new studies.
One study found that people who swam at a South Florida beach for just 15 minutes were more likely to fall ill over the next week compared with people who stayed on the beach, even though there was no known source of contamination there.
The other study, released by the National Resources Defense Council, identified the country's best and worst beaches in 2009, based on monitoring data from coastlines across the country.
Nationwide, there were more than 18,500 beach closings last year, mostly for either known or suspected high bacteria levels. And 7 percent of water samples exceeded national health standards for illness-causing bacteria -- with some beaches failing more than 70 percent of the time.
The findings, experts say, shouldn't spoil the waning days of anyone's summer. Instead, the results point out the importance of practicing good hygiene at the beach. You might also want to check online for water quality reports before you pack your towel and sunscreen.
"We should all enjoy the beach," said Helena Solo-Gabriele, an environmental engineer at the University of Miami. "There are a lot of benefits, and we definitely encourage people not to avoid the beach. But if they are in a special group that makes them more at risk, they might want to reevaluate."
At some 3,000 beaches around the country (both on the coasts and on the Great Lakes), government officials regularly collect water and look for one or two specific types of bacteria that indicate contamination. Those bacteria, and the types that often come along with them, can cause skin rashes, gastro-intestinal illnesses and other problems.
When bacteria levels surpass thresholds defined by both the Environmental Protection Agency and individual states, beaches close. But even when swimmers are allowed in, bacteria linger in the water and levels often fluctuate more rapidly than measurements are collected.
To better understand how bacteria affects health in beach swimmers, Solo-Gabriele and colleagues enlisted more than 1,300 people to come to a beach in Miami. Half of beachgoers were randomly chosen to sit in a chair on a sheet of plastic on the sand. The other half spent 15 minutes swimming, during which they dunked their heads three times and filled a bottle with seawater.
Over the next week, the researchers reported in the International Journal of Epidemiology, swimmers were more than one and a half times more likely to develop a gastrointestinal illness, nearly four and a half times more likely to report having a fever or respiratory illness, and nearly six times more likely to report a skin illness.
Overall numbers were low, but rates of illness, especially skin rashes, were linked to levels of bacteria in the water they had collected while swimming.
"It's not like everyone who went in the water got sick," Solo-Gabriele said. "If you look at the actual numbers, the fractions are so small. But the rate of illness was higher in the swimmers."
There was no obvious source of pollution at this particular beach, and that is true in many places, said Jon Devine, an attorney at the National Resources Defense Council (NRDC), who worked one of the reports. More than half of the time, he said, officials can't identify the cause of bacterial spikes. When sources are known, the biggest culprits are storm water runoff, sewage spills and overflows.
New Hampshire, Delaware and Oregon, according to the report, had the cleanest shores. The most contaminated beaches were in Illinois, Rhode Island and especially Louisiana, where beaches exceeded national standards 25 percent of the time. Some of the worst beaches in Massachusetts, Indiana, Michigan and California exceeded standards more than 70 percent of the time.
The NRDC is pushing for better tests that give results immediately. For now, there is a 24-hour delay between test and results -- which can lead to large doses of exposure for swimmers.
"By the time you see information about beach quality, you're swimming in yesterday's water," Devine said. "You only know how good it was the day before."
To keep yourself safe in the surf, scientists suggest simple measures: Look for obvious sources of pollution, like discharge pipes, landfills or marinas. After you swim, take a shower and wash your hands with soap before eating. Avoid swallowing seawater. Think twice about swimming if you have an open wound or are very ill.
And if you're very young, very old or have a weakened immune system, you might want to keep your head above water -- or stick to the boardwalk, instead.