My friend is picking his nose and eating it in public. Should I just bring it up and say something? Or do I just let him keep living his happy life doing his thing? If I should bring it up, how?

He is old enough to be keeping this habit discreet, however, I have been watching it happen for a few weeks with building intensity. He is biting his fingernails, and picking his nose and eating all the remnants of everything. I’ve watched other friends observe the behavior and though no one has acknowledged it out loud to anyone, I think they have noticed it too.