Other than following players around at all hours and monitoring what they take at every hour of the day, or accessing comprehensive testing data, I don't know if there's a better way for knowing what's going on. Conversations with players/confidences shared by players are the closest thing to first-hand that there is.

But as long as we're attacking credibility, I could question whether you actually have a son playing football. Or whether he's legitimately on a DI program. Or whether he's so new to the program that he doesn't actually know how the older guys on the team get around drug testing, etc.

I could also point out that if he was doing anything questionable, you'd likely be one of the last people to know, not the first. A kid knows that their relationship with their parents is for a lifetime, and would probably be a lot less likely to confess indiscretions to a parent than to a friend. Your son is probably putting on his best face for you. Just something to think about.