In addition to the first response, you should never eat in a chemistry lab simply because those are the rules. I have worked in many science labs and they all had stated "no food or drink allowed".
For example, thermometers are frequently used in labs. Thermometers are fragile and break often. They contain mercury which is very lethal when ingested. If you place food near on mercury that may have spilled on the counter top and then you eat that food you may become very ill.
Other chemicals that spill may also leave residue that may linger for some time.