Purportedly the Netherlands, but the research was badly performed.
KNOWN PFAS contamination was around heavy industry, and yeah, if you live near those regions, maybe don't. Otherwise proceed with scepticism and/or some testing.
Fairly recent research claims that hobby (backyard) chickens tend to have higher PFAS contamination than factory farmed chickens because hobby chickens get the chance to eat (a lot of) rain worms whereas the factory farmed chickens only get commercial food, no live worms. I do agree that location is almost undoubtedly key to PFAS contamination rates.
KNOWN PFAS contamination was around heavy industry, and yeah, if you live near those regions, maybe don't. Otherwise proceed with scepticism and/or some testing.