Riptidessunburnsharks and — sand? It seems there's another potential beach hazard to worry about. A new study published in the journal Environmental Science & Technology found that the sand on a beach in Oahu, Hawaii, had more bacteria from fecal matter than the seawater that washed over it.

That’s right: The residents of your child’s sandcastle may be nasty bugs like E. coli and enterococci, meaning one souvenir from this year’s vacation could be some unpleasant tummy trouble for you or your family.

Related: How to Avoid a Shark Attack

The scoop on sand poop

It’s not the first time scientists have linked bacteria in beach sand to gastrointestinal illness. One study, of more than 27,000 people who visited seven different beaches around the country, found that digging in sand increased the risk of diarrhea in children under age 11 by 44 percent. Kids who were buried in sand were 27 percent more likely to get sick.

It also isn’t news that dry land can be germier than seawater: Scientists have found bacteria levels in sand that are 10 to 100 times higher than in the ocean.

What the new study shows is why that may be. The researchers write that certain bacteria, including “enterococci and C. perfringens, but not E. coli, showed significantly smaller decay rates in sand than in seawater.” (C. perfringens is one of the most common causes of food poisoning in the U.S., according to foodsafety.gov.)

In other words, some bacteria simply survive longer in sand, which allows them to build up to higher levels than in ocean water. This may be because bacteria in water gets more direct exposure to the sun, which speeds up its destruction. Bacteria deep in sand is more protected.

Related: Beach Lovers: How Dangerous is the "Flesh-eating" Vibrio Vulnificus Bacterium?

What’s a parent to do?

Regardless of how the bacteria got there (one reason: wastewater from sewage) or why it thrives in sand, there’s no reason to skip your shore vacation for fear of infection. Commonsense and vigilance should keep your kids from getting sick.

Discourage burying. There are several good reasons not to bury anyone in the sand. For one, the hole can collapse, trapping the person. For another, according to the EPA, one of the first studies to find an association between sand and GI illnesses found the people most likely to get sick were those who dug into the sand or were buried in it. 

Use hand sanitizer. It’s just as important to pack hand sanitizer in your beach bag as it is to bring sunscreen. Every time you reapply sunscreen and before your child eats anything, have him rub a healthy dollop of sanitizer into his hands.

Wash hands when you can. Dipping hands in the ocean will wash off grit, but it won’t rinse away all germs. After all, they’re in seawater as well. You’ll need soap, water and scrubbing to chase them away. 

Teach little ones not to eat sand. Babies and toddlers may put sand in their mouths on purpose, just to check it out. If your little one decides to have a taste, gently move his hand away from his mouth, say “no” and distract him with something safe to play with.

Related: Ocean Toys: A Raft of Trouble?