HORRY COUNTY, SC (WMBF) - Swimming in the ocean is known to make people sick, but even higher levels of bacteria are in another part of the beach, the sand.
"Compared to the water column, your number of bacteria will be often 1,000 times greater in sedimentary habitats," said Eric Koepfler, a marine biology professor at Coastal Carolina University.
Koepfler said that's because the conditions are ideal for bacteria to survive in sand. The sand has organic matter, which the bacteria feeds on, and also less exposure to sunlight, which kills bacteria.
"In a sandy habitat, ultraviolet energy penetrates probably only a couple millimeters beneath the surface," he said.
The majority of the bacteria in the sand is natural and won't make a human sick, but there are exceptions, Koepfler said.
A new study from the University of Hawaii at Manoa found fecal bacteria lives longer in the sand than it does in the water.
"In many respects those conditions are more like what they would experience when they're found inside of their host," Koepfler said.
WMBF News Reporter Amy Lipman tested sand in Myrtle Beach and Briarcliffe Acres to determine if there's any fecal bacteria in the sand. The test from Pace Analytical found fecal coliform in both samples. The amounts reported were more than 111 times the minimum detectable amount. Pace Analytical said fecal coliform is an indicator bacteria, so it shows the potential presence of E.Coli or other pathogenic fecal bacterias. However, this is not a complete study of the presence of fecal bacteria on the Grand Strand and it doesn't indicate whether or not this is a health risk to the public.
The South Carolina Department of Health and Environmental Control does not monitor sand bacteria. The organization tests ocean water once a week. People are still allowed to be on the sand when high bacteria levels are detected in the water.
To see an interactive map of water bacteria test results for Grand Strand beaches, click here.
"It has taken a lot of effort to develop a good sampling strategy and regulatory framework for the water. That has taken decades," said Susan Libes, director of CCU's Waccamaw Watershed Academy. "It is still to some extent a work in progress. I would anticipate the same thing for trying to develop regulatory tools for beach sand."
Libes said public health risk is what prompts regulatory testing.
Studies that evaluated the health risk of sand exposure are numbered, but in 2007, Environmental Protection Agency researchers did survey 4,999 people about their beach activities. The researchers then asked the same people two weeks later if they experienced any stomach upset or other symptoms of gastrointestinal illness. By doing that, the study found people who reported digging the sand, and especially being buried in the sand, were more likely to develop GI symptoms. However, the study recognizes the difficulty in pinpointing the illness to sand versus water.
The EPA recommends people wash their hands or use hand sanitizer after playing in the sand or water.
Libes said people can also prevent the spread of fecal bacteria in general by cleaning up after pets and disposing of baby diapers in trash cans that won't leak during storms.