Again, it is irrelevent since smoking something and eating it have different effects and we're talking about cancer and long term health risks here which is a chronic process. If you somehow manage to eat a toxic amount of tobacco, you won't die from cancer, you'd die from nicotine overdose. If you eat a toxic amount of nightshade, you'd die from atropine toxicity but the thing is not going to give you cancer. If you compare smoking weed chronically to smoking tobacco, weed has 5 times more tar in it so you'll probably die from bronchogenic carcinoma or from chronic obstructive pulmonary disease due to lung damage in either case. So it is not relevant comparing eating when we're talking about smoking here.