The Associated Press has produced an extensive report on the potential risks of RFID devices, which have been approved for use in humans. The report cites a range of animal studies that have linked similar devices to cancers in experimental animals, such as mice and rats. The report is generally well prepared and raises both scientific and ethical issues.

The ethical questions focus on the initial approval of these devices, which occurred while Tommy Thompson was in charge of Health and Human Services, a parent department of the FDA. The AP reports that five months after Thompson left government service, he joined the board of the company that produces the RFID devices. That position came with a substantial number of shares in the company. Attempts to obtain the safety information on the device that went into the approval process produced no documents.

Does relevant information exist? Absolutely; in fact, a company that produces similar devices intended to track research animals provides a list of references (scroll to the bottom) that includes a number of studies that link the use of implants to the development of cancers at the site of the implant. Although the development and progression of cancer in mice has some differences compared to humans, mice still remain the primary model system for understanding cancer. The rates seen in these studies (typically only a percent or two) should certainly have been relevant to the approval of human RFID implants.

It's important to emphasize that those studies are not necessarily sufficient to view these implants as known hazards. The data suggest that the devices foster cancer by causing inflammation of the tissues that encapsulate them. There is a large amount of scientific literature linking cancer and inflammation (the National Cancer Institute has some information on the matter). RFID tags turn out not to be the only form of animal tagging that causes cancer through inflammation; standard metallic ear tags can do so as well. That paper also notes that there have been a number of case reports where human prosthetic implants have induced cancers in the surrounding tissues.

Given that there's a known mechanism for these implants to foster cancer by irritating their surrounding tissues and that humans appear to suffer from these sorts of cases, there is clearly reason for concern. Still, it is possible that different RFID designs may have a greater or lesser tendency to induce irritation; more detailed studies are clearly needed. These should include more animals beyond mice and rats (RFID tags are used for pet identification purposes) and a detailed examination of whether those people who have received tags so far have signs of inflammation.

Should the FDA have approved the devices, given the animal data? Probably not without some basic studies of their potential to cause inflammation in humans. Although the animal reports are relatively obscure—the AP report quotes a variety of cancer researchers as being completely unaware of them—it's the FDA's job to find relevant research. Clearly, they dropped the ball here.