Somewhere along the line, I've read that not only purpleheart, but many of those exotic woods contain toxins which are unsafe for consumption. I agree that they are often used in cutting boards, etc., but how many woodworkers do you know, selling these items at craft shows, have a working knowledge of toxicology? They do have oils in them, which can readily leech into food.
That said, You can research it, but when it comes down to it, it's a matter of what you choose to believe. Unless you do the tox tests yourself, you're taking someone's word for it. So, I'd say, ask yourself how much food contact the item in question will have. What types of food? If it's just flour, leeching will be negligible, if at all. If it's moistened, leeching is more of a likelihood. How much leeching is the key question. And if it's acidic foods, it poses a different chemical reaction issue. And how much of these toxins would it take, over how long a period, for it to be significant.
I was a baker for 11 years. All of our tables and rolling pins were maple. Based on what I've read, it is a completely non-toxic, non-reactive wood. And it is the industry standard for wooden tables and pins. Although beech is often used in rolling pins, also. Despite the prettiness of the exotics, I always use maple for such items.