Frito Lay on their website has a list of Foods that contain no lactose or milk. Of course this sounds okay until I get to the bottom and read the disclaimer:
*The above products do not contain milk; however, they are produced on the same line as our products that do contain milk. Although the lines are washed between batches, a slight residue may remain on the line. Individuals who are extremely sensitive may be affected.
So what do I do with this information? For me, as far as my child is concerned, I consider these foods to contain milk and I won't be giving them to him. Of course my child's food allergy is pretty severe.
If your child has a mild allergy however, this site might be useful.