appeal to ignorance

Nobody has disproved it. That is not the same as it being true.

Wrong: “No one’s shown it’s harmful, so it’s safe.”

Right: “Has anyone actually tested it?”

Absence of evidence isn’t evidence of absence—unless somebody looked.

A claim with no evidence for it is not thereby supported. Unfalsifiable claims are especially good at this: if nothing could ever count against it, “you can’t disprove it” is a feature of the claim, not a point in its favour.

The legitimate version: if someone has genuinely looked, hard, in the place the thing should be, then not finding it is evidence. That’s how drug trials work. The difference is whether anyone searched.

Now go ask who carries the burden.