Read more on them here - http://www.bbc.com/news/technology-30144072
The American Medical Association (AMA) code of ethics released in 2007 to protect patients' receiving RFID implants emerged following an evaluation by the AMA's council on Ethical and Judicial Affairs (CEJA) which discussed ethical issues relating to using RFID implants for medical purposes.
Opinion 2.40 - Radio Frequency ID Devices in Humans
Radio frequency identification (RFID) devices may help to identify patients, thereby improving the safety and efficiency of patient care, and may be used to enable secure access to patient clinical information. However, their efficacy and security have not been established. Therefore, physicians implanting such devices should take certain precautions:
(1) The informed consent process must include disclosure of medical uncertainties associated with these devices.
(2) Physicians should strive to protect patients’ privacy by storing confidential information only on RFID devices with informational security similar to that required of medical records.
(3) Physicians should support research into the safety, efficacy, and potential non-medical uses of RFID devices in human beings. (I, III, V)
"...We've been putting chips in animals for 20 years," he points out. Now it is the turn of the humans."