RoadAbode more than likely hit the nail on the head. If the app says something like Share this item or send this item to a friend, that is when it will use your contacts to send info to a friend about the item. No need to get all paranoid. I would be more worried if some no name app that makes your phone a flashlight wants access to your contacts. I always try and stay with popular apps, or apps from known companies. More people put those to the test to make sure they are not stealing information.