My white boyfriend is friends with slutty girls. Should I be alarmed?

Is this a non-negotiable red flag? I don't think I can trust someone with character as such. They're friends even before I met him. But obviously, some if not all, are into him and would have no scruples stealing him from me. They're the type to post naked photos in public profiles. No offense meant, but they're so cheap and young. How can i bring it up without sounding annoying. I suspect he had history with at least one of them.