Is it safe to keep house hold chemicals bottles near food shelves - after all if one is careful enough not to add them accidentally to food while cooking ? Or are they volatile and will settle on our food items ?
By "chemicals" I presume you mean cleaning supplies. Such things do not migrate into food on their own. The only purpose in keeping them away from each other is due to accidentally spilling or pouring them into food.
As a chemist this makes the hair on the back of my neck stand up. One cardinal rule in a chemistry lab is not to eat or drink in the lab. So you are not going to instantly die, nor will you grow another ear, from have cleaning supplies near food items, but to me it is a really bad idea. The cleaning supplies should be stored in a separate location. Under the kitchen sink is typical.
In other words - !! PLAN AGAINST STUPIDS !! You don't want to accidentally spray your frying pan with roach killer instead of a spray oil.