OREGON STATE UNIVERSITY

Study Shows Surfers Ingest 10 Times More Water than Swimmers, Divers

12/23/2008

CORVALLIS, Ore. – A new study has found that surfers may unintentionally ingest 10 times more water than swimmers or divers, putting them at higher risk of contracting gastrointestinal illnesses when surfing in contaminated waters.

The study, which may be the first of its kind, was conducted by scientists at Oregon State University and the Oregon Department of Environmental Quality. It also suggests that because water quality at Oregon beaches is significantly better than more popular surfing destinations, such as California, Hawaii, or Florida, the risk of GI illness is lower for people surfing the frigid waters of the Oregon coast.

“While the risk for Oregon surfers is not high for GI illness, our findings suggest that surfers who spend longer periods of time in recreational waters, or who surf in more contaminated locations, are likely to be at higher risk of contracting GI illnesses,” said David Stone, an assistant professor in the OSU Department of Environmental and Molecular Toxicology.

The study, funded by Oregon Sea Grant, used a Web-based survey to collect voluntary responses from 520 of the estimated 12,000 surfers in Oregon. Participants estimated the amount of water they ingest during a typical recreational day, and the researchers used historic water quality data collected at six popular surfing beaches to calculate the risk of infection from fecal bacteria using enterococci as an indicator organism. (In 2004, enterococci was designated the indicator organism of choice for testing marine waters at public beaches that are used for swimming and other recreational purposes. Enterococci have been demonstrated to have a higher correlation than fecal coliform with many of the human pathogens found in marine water.)

The results of this Sea Grant study could be useful to public health and environmental officials responsible for beach sampling and advisory thresholds.

“On beaches popular with surfers, for example, officials might want to consider lowering the advisory threshold because surfers ingest higher doses of water than swimmers,” said Anna Harding, a professor in the OSU Department of Public Health who collaborated with Stone on the study.

Bruce Hope, an environmental toxicologist with the DEQ who also collaborated in the study, said the results could help regulators see the value of using more informative techniques instead of simple standards.

“Regulators often focus simply on whether an environmental condition, such as a bacteria count, is above or below some guideline or standard,” Hope said. “While this is useful and expedient, it can leave stakeholders wondering, ‘What’s the chance of my getting sick?’ This study provided the opportunity to apply risk assessment techniques to answer such questions, and, from the DEQ’s perspective, we were able to show that it was practical to use these more informative techniques to address real-world concerns.”

One of the study’s challenges was having surfers accurately estimate the amount of water ingested during a typical recreational day due to unanticipated head submersions, chaotic wave activity, and other factors of the sport that cause water ingestion. To help participants better estimate amounts, Harding asked them to select from common measurements instead of milliliters: a few drops, 1-3 teaspoons, the amount of a shot glass (1-2 ounces), or the amount of a juice glass (4 ounces).

Sixteen percent reported a few drops, 51 percent reported 1-3 teaspoons, 21 percent reported a shot glass, and less that two percent reported a juice glass.

Study participants were also asked to identify beaches where they had surfed in the previous 12 months from a list of six popular surfing beaches in Oregon: Short Sands Beach, Cape Kiwanda State Park, Agate Beach, Otter Rock Beach, Humbug Mountain Beach, and Bastendorff Beach. Water quality data indicated that Humbug Mountain Beach, the southern most beach studied, was the most contaminated, while Otter Rock Beach on the central coast was the least.

The researchers worked with the Surfrider Foundation, a grassroots environmental organization, and OregonSurf.com to post the online survey and recruit participants, who ranged in age from 18 to 64 and had surfed an average of 12 years.

“Surfers are always online checking the weather and surf conditions, so doing the survey on the Web with this population went very well,” said Harding. “Within two months, we had 520 unique responses.” Surfers are also interested in water contamination and are very environmentally aware, Harding said.

Pete Stauffer, the ocean ecosystem project manager for the Surfrider Foundation, hopes the study helps illustrate the need to reduce bacterial levels in coastal waters.

“The study’s findings demonstrate a key relationship between nearshore water quality and public health,” Stauffer said. “Given the prevalence of surfing and other forms of ocean recreation in Oregon, this provides additional justification for the need to monitor and reduce bacterial contamination in our coastal watersheds and ocean beaches.”

With an estimated 12,000 surfers in Oregon alone, the economic impact on coastal communities is significant.

“What’s comforting is that our study doesn’t suggest surfers are subjected to unacceptable risks for gastrointestinal illness.” Stone said. “But surfers should be aware that they are swallowing a fair amount of water. This is especially important when surfing after a big rainfall, near outfalls or in other locations where the level of contamination may be higher.”

Persons interested in news about science, marine education and related activities on the Oregon coast may subscribe to “Breaking Waves,” the Oregon Sea Grant news blog, at: http://seagrant.oregonstate.edu/blogs/