Your comment cherry picks the weakest language of the Wikipedia article and studies and ignores the rest. You’ll struggle to find any reputable study anywhere that says “our study proves that X does Y” like you’re asking, because thats not how studies language is conveyed and would be incorrect language to use in a medical study. When 20 studies all say “we have shown a strong correlation between cigarette consumption and cancer of the throat, mouth, and lungs” then you will hear scientists say “the link between cancer and cigarettes is known, and well studied” and news articles will say “cigarettes cause cancer”.

Your suggestion that the only way we’d know for sure is human trials of intentional PFOA exposure is… I’m gonna be generous and say… naieve. Scientists are perfectly fine with using lab, mouse, and emprical cross-sectional studies - that’s all valid scientific evidence. They don’t actually need to take the final Dr Mengele step of subjecting people directly to suspected toxins before they can already draw highly accurate conclusions, especially for something like PFOA that has large sections of the population with high dosages that they can compare against those with low dosages already.

It’s borderline impossible to actually separate out PFAS levels from these other entangled variables, people who are heavily exposed to 1 type of pollution will also be exposed to many others, and theres a heavy association between living situation and PFAS exposure.

Not true. Just one example, we have many population groups that live in areas where groundwater is used for drinking that also live near a firefighting training base/station that has released huge amounts of PFOAs into the aquifers. These populations are otherwise quite normally distributed for age/weight/health/occupation and exposure to other chemicals and perfect for study of PFOAs and have been shown in studies to have much higher levels in their blood serum.

It’s fine though - if you wanna sprikle PFOA on your cereal or something until 100 more studies are done, I can’t stop you. But just know that your tendency to cherry pick data and your unconventional assessment methods of studies is giving you a very poorly informed choice.