Whether you find them peering mysteriously out of your purse or at the bottom of your box of kale chips, you’ve probably wondered what those little "Do Not Eat" packets were doing there — you might have even panicked a bit, worrying you might have ingested some poison.

It turns out these packets aren’t really poison, but serve as moisture magnets, preventing water from seeping into products that are meant to be dry. These packets contain desiccants, which are materials that eliminate moisture. Desiccants create and sustain a state of dryness in their vicinity, and are often used in insulated windows, as well as in protecting goods like cocoa, coffee, nuts, and grains as they are shipped — they're vulnerable to moisture and mold during the process. They're also often placed in foods that could be damaged if moisture creeps in, such as bottled vitamins, dried meats, or kale chips. You may also be familiar with these little packets being inside clothing items or accessories, like purses.

A common form of desiccant used in these packets is silica gel, which is an artificial form of silicon dioxide. Silica gel adsorbs water — that’s right, not absorbs — in order to prevent food from getting moist. They come in the form of small, clear balls.

Adsorption (with a d) is quite different from absorption. During absorption (with a b), water is drawn into a material, such as when your clothes get wet after being rained on. Adsorption, however, involves a material that causes water molecules to stick to it instead of being absorbed. Silica gels are so effective at adsorbing water through their tiny microscopic pores that one single grain can adsorb 40 percent of its weight in water.

According to the Illinois Poison Center, silica gel is minimally toxic and can’t cause poisoning. As to why you shouldn’t eat it: “I mean if you tried, it wouldn’t kill you, but it would adsorb all the moisture in your mouth, including your gums and tongue, causing so much discomfort that the Cinnamon Challenge would look like a great idea in comparison,” the video's host said. If you do happen to try it — and we're definitely not encouraging that — drink lots of water to counteract the effects.