It's interesting to me that people worrying about PFAS at 0.004 ppt levels consider Reverse Osmosis filters made from PTFE membranes a way to remove them. What

It's interesting to me that people worrying about PFAS at 0.004 ppt levels consider Reverse Osmosis filters made from PTFE membranes a way to remove them. What are the PFAS levels in the membrane? Who tested it? Charcoal filters are only removing 3/4 while RO is removing 19/20, but if you're at 70ppt, you're not getting to 0.7ppt even with both of those together. If you believe the people testing, why not believe the same for tested teflon pans? I still suspect RO is pretty good since otherwise semi fabs would be contaminated, but I think the PTFE boats were probably also pretty good. It's the thousands of gallons of PFAS by-product pumped into the ground or sold off as flame retardant that I'd worry about.