Alex uses chewing tobacco every day and has done this since he was 15 years old. he notices leathery white patches inside his mouth. what is this condition

The answer is Leukoplakia. When you have this condition, there is a thickened, white patches that form on your gums, the interiors of your cheeks, the bottom of your mouth and, occasionally, your tongue. These patches can't be scratched off. Specialists don't know what the source of leukoplakia is but consider chronic irritation from tobacco - whether dipped, smoked, or chewed - to be the main reason in its development. Most leukoplakia patches are noncancerous meaning that they are benign, though some show initial signs of cancer. Cancers on the bottom of the mouth can happen next to areas of leukoplakia. And white areas varied in with red areas (speckled leukoplakia) may specify the potential for cancer.