is broth that hasn't been boiled safe? I was making turkey broth last night in the oven (turkey bones and leftover meat in a stockpot in a 170 F oven for 6+ hours). I read about this technique on a chef's blog, which I can find if needed. 

Then I got to thinking. The broth certainly has bacteria in it from the turkey carcass. And all those bacteria are sitting in water, with plenty of proteins floating around in a nice toasty oven. Is all this bacteria + protein + water + heat safe? It seems like broth should be unsafe at the least. Is 170F enough to kill the bacteria that would be present here? 

On the other hand, chefs have been doing this for quite a while and everyone seems fine.
170 degrees is perfectly fine. 

To talk bacteria, you have to take into account two factors: temperature, and time. Anything between 40 and 140 is good for them, anything above 140 is bad. At the same time, food in the dangerzone that is eaten/cooked/frozen promptly, is fine, because it takes time to build up a colony of harmful proportions.

In this case your temperature is 170 degrees, which is hot enough to kill most common bacteria instantly (Milk is pasteurized in the 160s), and then you keep it at that temperature for hours? The toughest common bacteria (C. botulinum) dies very quickly at 180 degrees...It's the only one I know off the top of my head that doesn't immediately die in the 170 range. And keeping your stock at 170 for 10 minutes or so will kill any C. botulinum that may have somehow found it's way inside it.

You've got nothing to worry about.

(Basics of TDT calculation)