There isn't much (or any) research on the effects of PFAs on humans, only on lab animals, so we really don't know anything about its toxicity to us. What we do know, however, is that these organic molecules have an extremely rare combination of characteristics: they are unbelievably stable (they seem to be both both hydrophobic and hydrophillic), they can bind to a significant fraction of common proteins indiscriminately, and there exists no biological mechanism that can effectively filter them out. Even though we don't yet know how toxic the compounds are, we do know that this behavior creates a perfect shit storm because not only do these molecules interfere with basic biochemistry but also bioaccumulate though environmental exposure (drinking contaminated water) and the food chain.
The closest analogy would be prions which are also very stable, interfere with the basic function of proteins, and can accumulate through a variety of exposure vectors. The difference is that prions coevolved with the rest of our ecosystem whereas PFAs are entirely synthetic and do not exist in nature. It's unlikely that these molecules are as toxic as arsenic (which wrecks havoc by replacing phosphorus in DNA and the Krebs cycle) but this rather unique combination of circumstances requires an extreme level of caution.
This is what makes PFA molecules so potentially dangerous: they don't behave like anything we've seen in natural biochemistry. Since they have both a hydrophobic carbon chain and a hydrophilic functional group containing fluorine, no known protein can break them down and no known biomechanical mechanism can filter them out so they remain in the blood indefinitely. At the same time, however, the carbon chain and functional group are free to bind onto other proteins as long as the molecules are oriented in the right way, which invariably prevents the other protein from functioning correctly.
Maybe, but not for a very long time. You'd have to develop an otherwise inert enzyme that can go through cell membranes and spread to every cell in the body. Theoretically this would be feasible using a retro virus that can infect every cell and instruct it to produce the enzyme but we're basically just getting our feet wet with genetic engineering research that is bound to take decades or centuries to get to that point.
Dialysis wouldn't do a thing since most of the toxic molecules arent going to be in the blood plasma.
No, activated carbon filters are actually very effective at removing PFAs. The filters work mechanically by trapping the molecules which works well because of the long carbon chain in PFAs. This mechanism is far simpler than reactions in protein chemistry because it doesn't require complex interactions with a solvent (which is where being both hydrophobic and hydrophillic becomes a problem).
The closest analogy would be prions which are also very stable, interfere with the basic function of proteins, and can accumulate through a variety of exposure vectors. The difference is that prions coevolved with the rest of our ecosystem whereas PFAs are entirely synthetic and do not exist in nature. It's unlikely that these molecules are as toxic as arsenic (which wrecks havoc by replacing phosphorus in DNA and the Krebs cycle) but this rather unique combination of circumstances requires an extreme level of caution.