Medical milestone or privacy invasion? A tiny computer chip approved ... for implantation in a patient's arm can speed vital information about a patient's medical history to doctors and hospitals. But critics warn that it could open new ways to imperil the confidentiality of medical records. The Food and Drug Administration said ... that Applied Digital Solutions of Delray Beach, Fla., could market the VeriChip, an implantable computer chip about the size of a grain of rice, for medical purposes. With the pinch of a syringe, the microchip is inserted under the skin in a procedure that takes less than 20 minutes and leaves no stitches. Silently and invisibly, the dormant chip stores a code that releases patient-specific information when a scanner passes over it. The VeriChip itself contains no medical records, just codes that can be scanned, and revealed, in a doctor's office or hospital. The microchips have already been implanted in 1 million pets. But the chip's possible dual use for tracking people's movements ... has raised alarm. If privacy protections aren't built in at the outset, there could be harmful consequences for patients," said Emily Stewart, a policy analyst at the Health Privacy Project. To protect patient privacy, the devices should reveal only vital medical information, like blood type and allergic reactions, needed for health care workers to do their jobs, Stewart said.