They’re not really a nuisance, like the layers of tape and bubble wrap you have to fight through to open packages. Silica gel packets are just there, omnipresent in everything from blenders to Birkenstock boxes. But what exactly is the purpose of Silica gel packets and why can’t we eat them?
The reason why they’re so crucial is because they’re a cheap and effective desiccant, an agent which is used to suck water vapor out of the air and keep an environment dry. For leather products, a dry environment is crucial for staving off mold and preventing shrinkage. The reasoning is similar when it comes to food, as a damp environment is prime for bacteria development and accelerated spoilage. Electronics and water don’t mix well, either. In fact, the silica in kitty litter is the prime reason why you can use it to defog your car windows, too.
Although the packets explicitly say “DO NOT EAT” on them, Silica, or silicon dioxide, it’s relatively harmless which is why it’s fine to store in food packaging. Slate noted that, sure, you could eat the packet if you wanted to. The stuff can absorb 40 percent of its weight in moisture, but consumption is just going to drain your fluids, so you probably just shouldn’t eat it at all.
[Source: How Stuff Works]