I've seen some indications that many people in the public health field feel that
everything that affects morbidity and mortality is potentially within scope for them, including, for example, intentional actions like assault or murder.
A difficulty with this view, at least potentially, is that it seems to allow everything in the world (certainly almost every area of public policy) to be in scope for public health, because almost everything in the world has potential to affect morbidity and mortality. At one level this broad view seems obviously correct, but at another level it seems obviously crazy (or at least likely to bring the public health profession into conflict with everyone over weighing in on every kind of decision that anyone ever makes).
In the past there was a fight between some CDC researchers and Congress over something about handgun policy because the researchers were studying something about guns and violence that made some gun rights activists nervous that there would be an argument presented under the banner of public health to limit access to guns. I believe the conclusion was that they told CDC to stop studying this, which, again, seems to me to be susceptible of some mix of "there might be a lot of legitimate reasons to have this information" and "does the public health profession get to weigh in with claimed expertise on every issue?".
I think it's a legitimately thorny conceptual problem because if you think of health as something like "flourishing" or "people having success in living the way they want" or "eudaemonia" or something, almost every public policy question can be conceived of as a "health" question. (Or even, maybe, "minimizing all-cause mortality"?) But if someone says that the policy answer to each question is therefore obvious because a particular profession thinks it knows what would maximize things it thinks it knows how to measure, I imagine a lot of the public is going to say that this doesn't match up with its notion of what health is.
Edit: after writing this, I had this weird imagine of public health as like a superintelligent AI that's super-focused on one goal and doesn't understand, or doesn't care very much, that people might have other goals too. We think there's obviously something that's going to remain outside of the scope of the AI's interest, but since the AI is smarter than we are, it discovers a way that that thing is actually relevant to its interests according to its utility function, after all! (I realize people have also had this kind of concern about other institutions that are happy to define their scope of action more broadly over time, such as profit-maximizing corporations, or militaries. The corporation says "we need to figure out what actions will maximize profit" or the military says "we need to figure out what actions will maximize our capacity to win wars" and perhaps the scope and ambition of their actions are soon larger than anyone would have expected.) I feel like this analogy is actually weirdly apposite, at least for some audiences. :-)