This is for sure a concern. Also when my RO system was first installed, the filter instruction said to run it to fully empty twice to run out the detergents (?) that the filters came with? I have to wonder what's in that, or lubricants used in construction.

I would not be surprised to find PFAs used somewhere in the construction of the system. Under regulation of this stuff means it's everywhere.

But then again, lots of the pipes, fixtures, etc. in the house ... plastic etc. as well.