D.B.
If this is just starting (the party stuff), then I think a call to the parents to say, "I understand there is a party on X date and I just want to make sure that you are aware of it and will be supervising." Then you can add in, "I'm not sure how many kids you are expecting, and I wonder if there's something I can do to help you with preparations or to help manage the crowd. I know it's hard to do all the work and then go in and out of the party without being a nuisance but still keeping an eye on things." That makes you sound cooperative and also vigilant. You'll get some idea from their tone about how they are handling things.
I think there are all kinds of concerns: drugs & alcohol, sure. But also, what happens if uninvited kids show up and it gets out of hand? What about unsecured firearms or prescription drugs in the house? Some kid goes the bathroom and rifles through the medicine cabinet or the gun cabinet while the parents are busy making popcorn and appetizers? So your safety issues with your daughter need to cover all the bases.
Do you have a code with her? If not, google a safety word or code that she can text you if things get uncomfortable. We had a pact with our son (you can find them on line) which was that we would come get him anytime, and we would endure any bad stuff he said about us if it was his way to extricate himself from a dangerous or uncomfortable situation. We didn't care if he saved face by telling his friends that his damn idiot parents (insert any 4 letter words you want) were demanding that he come home now because we had some stupid curfew or wanted him to visit with Aunt Agnes - we went and got him. We also had a deal that, if he called us due to drinking or drugs (him or others), we would not ground him or punish him for it, nor would we even discuss it that night - we'd just get him home. There's a common idea to text "X" to your parents but too many people know that one. The idea is, if anyone sees his phone, the texts look innocuous. So something like "Did you buy more cheese" or "did you iron my blouse for tomorrow" would work better. So it's more important for you to set the stage now and tell your daughter that you KNOW this situation will occur, maybe not this week or this month, but at some point, and there has to be an agreement that protects her without penalizing her for telling you.
We did this very early with our son, and it worked really well. He knew we were monitoring things and loved him, and would be the "bad guys" if need be. When he got picked up in college for underage drinking, he had to call us and tell his coach - and that was a hard call for him to make. What we said was, "We know this was a really hard call for you to make!" We added that there was nothing we could say that would make it worse that what he'd already been through, and he'd have to endure the consequences (missing a meet and whatever else was meted out). He never did it again. That was the goal, and it worked.
So talk to your daughter. You may get the "eye roll" and the "Mooommmmmm, my friends aren't like that!" To which you say, "I know, but sometimes other kids show up and your friends may not know how to handle it. If you get picked up by the cops for being in the wrong place at the wrong time, there's nothing we can do. So, like fire drills, let's have a plan just in case, and hope it never has to be used."