apple wood is safe. i use it for a lot. i hear that black walnut may not be good to use, but i would research that before making a decision. the thing is, a lot of people use woods like choke cherry, not realizing that they can be toxic. even the fruit can be if you dont get rid of the seeds. sure you probably wont die from smoking a pork shoulder or drinking a glass of mead made with it, but you're still putting those toxins in you. cyanide is not a joke and certainly something not to be taken lightly. i would use the fruits in a mead, but i'd have to get rid of the seeds first. that being said, i'd probably just rather use a different fruit.