I see this kind of argument so often from PFAS apologists - "we don't have conclusive proof yet that it's harmful so we should keep producing and using this substance which is known to bioaccumulate and never break down". Shouldn't the onus be on those who want to use it to prove that it's safe? If the studies we have are truly as inconclusive as they claim, doesn't that just mean that we don't have good evidence they're safe?