Concerns from privacy groups about radio frequency identification (RFID) could be an obstacle to adoption. When German retailer Metro Group is experimenting with RFID, and invited an RFID privacy critic to its store to demonstrate the system, it was charged with storing privacy data in its loyalty cards that cannot be erased. One use of Metro's cards is age-verification for previewing videos. Most RFID users are tapping the system for tracking products. However, legislators are also becoming concerned about possible privacy abuses. U.K. store Marks & Spencer is experimenting with detachable RFID tags that are not scanned at checkout to avoid associating products with individuals. The Electronic Frontier Foundation compares RFID to pollution. Another overlooked potential problem with RFID is that it could make corporate espionage easier. RFID technology is years away from being advanced enough to create most privacy problems. However, companies need to prepare as it gains capability. Most consumers will trade some privacy information for other things of value. However, the technology is too new to determine how far the trade-off will work. Alexandra Hospital in Singapore uses RFID to track ER patients, saving staff time. The U.S. Department of Defense believes RFID can improve supply chain security. Openness about the system will help, but will not overcome bad decisions about privacy policies.