A big issue with things like PFAs is that they bioaccumulate. They build up faster than the body can metabolize them. This increases the likelihood of toxicity because the level in your body just keeps building.
There’s also biomagnification, which is where a substance (in this case PFAs) grow more concentrated in organisms higher in the food chain. It’s in everything. It’s in the things we eat, and it’s in the things they eat, and it’s in the things those things eat, all the way down.
It doesn’t matter if things aren’t toxic now, because they will be given enough time.