Saunas helping with any kind of detox is complete hocum.

Blood donations clearly do.

Microplastics and PFAS aren't synonyms however.

What isn't established is a dose dependant harm from PFAS. Some things are harmful in minute quantities to the point it doesn't matter if you have a lot or a little.

Lead has a clear dose response but a relatively low threshold for noticeable harm. It's not clear what PFAS curve will look like.

I won't restart the linear no threshold flame wars about radiation harm but let's just say it's not always intuitive.