Have you ever wondered what’s on your kids’ hands that you can’t see with the naked eye? A viral photo suggests there is a lot of stuff on the skin of your average 8-year-old.

This photo is all over the internet right now, but it was captured in 2015 by mother and scientist Tasha Sturm, who pressed her then 8-year-old son’s hand after he had been playing outside and touching the family dog.

After two days she had a collection of bacteria and yeast which she shared on the website Microbiome World.

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The yellow and orange spots are thought to be yeast, while some of the white spots are believed to be Bacillus (common in water and dirt) and Staphylococcus. Staphylococcus can cause staph infections, but Sturm wasn’t panicked about seeing it on her son.

“It’s normal stuff that we’re exposed to every day. The skin protects us from a lot of the bad stuff out there,” Sturm told Today back in 2015. “The take home message is that to have a healthy immune system, you’ve got to be exposed to stuff.”

While parents, of course, want to make sure kids are washing their hands before eating or after dirty activity, letting our kids get dirty (and therefore get exposed to various bacteria and germs) is actually good for their health.

As Jack Gilbert, Ph.D., a scientist who studies microbial ecosystems at the University of Chicago and the co-author of Dirt is Good: The Advantage of Germs for Your Child’s Developing Immune System told NPR, parents don’t need to worry about over sanitizing kids. He says hand sanitizer can do more harm than good and actually make children more prone to allergies.

“Their immune systems then become hyper-sensitized. You have these little soldier cells in your body called neutrophils, and when they spend too long going around looking for something to do, they become grumpy and pro-inflammatory. And so when they finally see something that’s foreign, like a piece of pollen, they become explosively inflammatory. They go crazy. That’s what triggers asthma and eczema and often times, food allergies,” says Gilbert.

Instead of hand-sanitizer, Gilbert recommends old fashion soap + water. Even mildly warm, soapy water is fine, and it’s probably less damaging to the child’s overall health, he explains.

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