“Q: If there’s no safe way to use products with microbeads in them, what’s a safe way to dispose of them?”
I am actually facing this problem myself, anon! I have a bottle of the stuff that has been sitting for months in my shower. Judging me. Tempting me with its exfoliating properties.
For those unaware, microbeads are small plastic beads that are added to all kinds of stuff for various reasons, and they are TERRIBLE for the environment. They easily pass through water filtration systems and end up adding to pollution, or getting eaten by animals. Microbeads can be found in a lot of products like - as mentioned - exfoliating facewash, bodywash, toothpaste, etc.
As far as I can tell, from a quick scan online, the only way to “dispose” of them is to close up the container and chuck it in the garbage. Going to landfill, as depressing as it is, is a better option than draining it into the water. You could try sending it back to the manufacturer, maybe including a strongly-worded letter to the effect of “your product is garbage and you single-handedly murdered like four hundred baby albatrosses you monster”, but it varies from company to company on if they accept returns.
Other than that, there’s not much you can do with the stuff you already own. I know the US just banned them, and hopefully more countries follow suit. Just be careful what you buy in the future, and avoid any products that contain polyethylene or polypropylene!