Eating in Science labs and Classrooms

Eating in Science labs and Classrooms - We have received a few questions on this topic

1. Is there any documentation to support not eating in a science laboratory? And how do you suggest that this is adopted?
2. Are all school laboratories classified as PC1 laboratories and if so are students permitted to eat in classrooms? For example, when a teacher wants to demonstrate digestion practicals, can they eat shop bought items such as biscuits, lollies to demonstrate why mastication is important or if they've used food as a model e.g. snack tectonics, can the students eat them? When practicals revolve around the making of cheese or yogurt using lab equipment can the created items be consumed?