You wouldn't know if maybe the strangers did something bad to your food. You might want a throw food away just in case. You might feel uncomfortable because maybe the strangers looked in your diary. These would all be indications of a breach of control. Security people next consider the issue of integrity.
Integrity refers to being correct.
For example imagine how bad you would be if somebody took one of your exam papers and change it so that your answers were now wrong. This would be a breach of integrity. If someone were to take a check that your parents wrote and then changed the amount payable, that would be a breach of integrity. Changing information without permission is a breach of integrity. There have been cases where criminals have altered medical data.