Next time your stomach doesn't agree with you after a day at the beach, don't blame that hot dog that you ate. It could have been the sand. A recent study in the American Journal of Epidemiology found that people who played in beach sand were more likely to get some form intestinal disease. More specifically, poop is the culprit. Whether it's from a lazy owner's dog or from a wild animal, the waste gets washed to the beach by the rain.
The best ways to stay healthy are to use a hand sanitizer while at the beach and to shower thoroughly afterward.