I had a similar problem years ago when I first started in this position. Fortunately, I did not have to convince any of the faculty or administration that this was unacceptable (the problems with food and drink in a chemical/biological lab were noted long before I was born). I just began to reprimand students for doing this and notifying their advisers that I had done so. The culture caught on and I rarely find this going on anymore. A simple reprimand is all it takes, you should not need penalties. If your faculty is not on board, you may have to gather them up in a meeting with their dean and explain the problem.