Researchers from the University of North Carolina at Chapel Hill and the Environmental Protection Agency have said that digging into sand may be an invitation to gut bugs.
The researchers say that people playing in the sand are at a greater risk of developing gastrointestinal diseases and diarrhoea than those who only walk on the shore or swim in the surf.
And those who playfully bury their bodies in the sand are at even greater risk, according to the study.
The study also showed that children, who are more likely than adults to play with and possibly get sand in their mouths, stand the greatest chance of becoming ill after a day at the beach.
"Beach sand can contain indicators of faecal contamination, but we haven't understood what that means for people playing in the sand. This is one of the first studies to show an association between specific sand contact activities and illnesses," said Dr. Chris Heaney, lead author of the study.
The findings have come after interviews with more than 27,000 people who visited seven freshwater and marine beaches in the agency's National Epidemiological and Environmental Assessment of Recreational Water Study (NEEAR) between 2003 and 2005 as well as in 2007.
Heaney said that all beaches in the study had sewage treatment plant discharges within seven miles, although the source of sand pollution was unknown and could have included urban runoff as well as wild and domestic animal contamination.
Water quality at the beaches was within acceptable limits.
People were asked about their contact with sand on the day they visited the beach and health symptoms were confirmed on phone after 10 to 12 days.
Researchers found evidence of gastrointestinal illnesses, upper respiratory illnesses, rash, eye ailments, earache and infected cuts.
Diarrhea and other gastrointestinal illnesses were more common in about 13 percent of people who reported digging in sand, and in about 23 percent of those who reported being buried in sand.
"A lot of people spend time at the beach, especially in the summer. And while we found that only a small percentage of people who played at the beach became ill later - less than 10 percent in any age group, for any amount of exposure - it's important to look at the situation more closely. If we find evidence that shows exposure to sand really does lead to illness, then we can look for the sources of contamination and minimize it. That will make a day at the beach a little less risky," said Heaney.
The study has been published recently in the American Journal of Epidemiology.