Here is an unusual tip, I hope. I had stored some pool shock in a pantry. It was in the original package (plastic bag) and then in a gallon jar. A couple of years later I was reading about pool shock being potentially dangerous, so I gave it to someone with a pool. Now I am finding store bought cans of food in the same pantry rusting. Some brands and certain foods seems to be rusting more, such as pumpkin. Nothing has rusted through, but food is being used up, given away, and cans being sanded. I believe rust also just spreads by itself if not caught. It also rusted some metal shelving in my DS's pantry.