Is it more humane to launch it without testing, producing the same effect for a much, much larger group of people than would have been involved in the intentional study? This seems to be a fairly gaping hole in the definition of humane. It reminds me of people who see an accident and don’t help because they might be held liable for the accident and they don’t want to get involved.
Prohibiting new chemicals outright would be fine, but that is pretty far from where we are today.