system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are plastic microbeads in facial washes and soap so much more dangerous than sand, which is already common in lakes and oceans?

Also pumice and ground peach pits, which we've been putting in soap for decades?
gpt
It's not the size of the beads that's the direct problem, it's what they're made out of. Ingesting plastic can lead to hormonal changes and other impacts that don't happen when ingesting those other things.

In a sentence: Plastic is toxic, pumice, peach pits, and sand aren't.