How about this for a general statement......you should assume botulism spores are always present on meat. They start producing toxins in a warm, moist oxygen free environment between temps of 40 and 140 degrees F. Pretty much the exact conditions you will get in any smoke attempt.
Those toxins are some of the most lethal poisons known to man. So......the rule is you don't smoke anything unless you put some nitrite in it. It doesn't cost much, is easy to add and other than changing color of cooked meat, you really won't know it's there. Why risk going without it? Said another way, don't cold or hot smoke anything without it! (hot smoking is not the same as grilling or even slow cooking at temps of 225 degrees F and up).
PS: I've been using light, steady smoke for 2 to 4 hours on my stuffed breakfast sausage. Apple or cherry wood. Like eating candy!