Regarding the "reducing mortality" example, in biostats, mortality is "death due to X, divided by population". So "reducing cardiovascular mortality" would be dangerous, because it might kill its patients with a nerve poison. Reducing general mortality, though, shouldn't cause it to kill people, as long as it agrees with your definition of "death." (Presumably you would also have it list all side effects, which SHOULD catch the nerve-poison &etc.)