I don't think you need counterexamples, because your base argument is faulty. Food full of formaldyhde only causes harm as the product of human usage, i.e. someone eating it, regulation aims to make it impossible for such a situation to arise. For a less extreme but no less real example, just look at the regulation of raw milk in much of the world.

Elsewhere in the thread you have touched on firearm regulation; it's worth noting that amongst states with the capacity to do so, it is really only the US that abdicates its responsibility to regulate firearms, with predictably tragic consequences (though, as with everything in the US, that varies state to state etc.)