Scientific Studies Show Bacteria in Sand at Some Beaches; Clean Beaches Council Calls for More Research, Monitoring of Sand

WASHINGTON, July 15 -- Several scientific studies conducted in the last four years at select fresh water and marine beaches around the country show that indicator bacteria (e.g., E. coli) exist in sand, according to a report released today by the Clean Beaches Council. In a number of cases, these bacteria are more highly concentrated in beach sand than in water. Entitled “2005 State of the Beach Report: Bacteria and Sand,” the report is the first in-depth look at the current research on bacteria and beach sand and summarizes the findings of recent comprehensive scientific studies on this subject.

Environmental agencies and health departments regularly test the swimming water at beaches for the presence of indicator bacteria, which in large concentrations can prompt the closing of beaches. But not until recently, have studies been conducted to determine the presence of indicator bacteria in the sand itself. (Indicator bacteria are microbes that do not, in themselves, cause illness but suggest that fecal matter may be present, which can present a health risk.)

According to these studies, because sand bacteria survive longer than water-borne bacteria, beach sand may serve as a reservoir of indicator bacteria and affect the health of sensitive adults and children who spend a lot of time in wet sand.

“This report on bacteria in sand at our nation’s beaches is a call to action,” said Walter McLeod, president of the Clean Beaches Council. “While these data are based on a limited sampling of beaches, they clearly indicate that beach sand can be a source of indicator bacteria. We hope this report is a catalyst for more research on the relationship between bacteria and sand and the potential affects on human health.”

A 2003 U.S. Geological Survey (USGS) study conducted at a freshwater beach in Chicago found that indicator bacteria levels in sand averaged 5-10 times higher than levels in adjacent swimming waters. During the course of this study, the city replaced the contaminated sand with truckloads of fresh sand, however within two weeks, indictor bacteria levels were similar to those collected before sand removal. What surprised the scientists most was that these indicator bacteria remained consistently high regardless of beach water quality.

A 2001 study at two beaches in Miami-Dade County, Florida found indicator bacteria in marine sands. The results suggest that the shoreline is the primary source of microbes and that this source is most pronounced during high tide when the water level reaches its highest point along the shore.

A 2001-2002 study at beaches in St. Clair County, Michigan found that fecal indicator bacteria were more abundant in sand than in water. Indicator bacteria counts were 3-17 times higher in sand than in water, suggesting that sand may be a reservoir of fecal bacteria.

When faced with a swimming advisory, many beachgoers enjoy sand play activities. Children are a particular concern because they spend more time playing and digging in the wet sand and more susceptible to intestinal illness. Currently, however, there is no evidence that links illnesses to sand exposure.

“We simply don’t know how polluted sand affects human health. And while we now realize that sand may have a high number of indicator bacteria, we do not know the medical implications of its presence,” stated Dr. Richard Whitman, station chief at the Lake Michigan Ecological Research Station at the USGS in Porter, Indiana and the leading authority on sand and bacteria.

Some of these indicator bacteria may be directly deposited by shore birds. These birds can carry human pathogens such as Salmonella in their feces. Other times, the bacteria may have accumulated by drift and sedimentation. However, there are few studies on this subject, in part because of the newness of the discovery and the difficulty of interpreting the meaning of the results to date.

“Water monitoring has improved dramatically and today many states monitor their beaches about every two weeks,” noted Dr. Elizabeth Alm, a microbiologist with Central Michigan University. “But to make beaches healthier for the millions who visit each year, we must better understand whether contaminated sand may be the source of bacteria to swimming water.”

“It is much harder to monitor sand,” added Whitman. “There is no standard way to measure the bacteria or common units of measurements. Also, scientists don’t agree on what the numbers mean. New studies are needed to evaluate the disease potential of exposure to disease causing agents in beach sand.”

In conjunction with the release of today’s report, the Clean Beaches Council called on leaders in government and the scientific community to launch a national science initiative to study the relationship between sand and bacteria, establish a global network of researchers, and establish a national network of beachgoers committed to increasing beach science literacy through education, outreach and action.

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About the Clean Beaches Council

The Clean Beaches Council is a nonprofit organization devoted to sustaining America’s beaches. Since its inception in 1998, CBC has developed innovative approaches to coastal management and protection of human health and the environment.

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Beach b-roll footage is available upon request.

Contact Information

Carrie Collins

Media Contact

Clean Beaches Council

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