One of the main concerns with RFID tags is that their contents can be read by anyone with an appropriately equipped scanner – even after you take it out of the store.
One technology that has been suggested is a zombie RFID tag, a tag that can be temporarily deactivated when it leaves the store. The process would work like this: you bring your purchase up to the register, the RFID scanner reads the item, you pay for it and as you leave the store, you pass a special device that sends a signal to the RFID tag to “die.” That is, it is no longer readable.
The “zombie” element comes in when you bring an item back to the store. A special device especially made for that kind of tag “re-animates” the RFID tag, allowing the item to reenter the supply chain.