Embedding microchips in humans scares some people on privacy grounds alone. Now the chips are raising alarms for a different reason -- a potential link to cancer.

Studies done in the 1990s found that chip implants had "induced" malignant tumors in lab mice and rats, according to this AP story.

The Food and Drug Administration approved the VeriChip by Applied Digital Solutions for use in humans in 2005. At the time, the man in charge of the Department of Health and Human Services, which oversees the FDA, was Tommy Thompson.

Two weeks after the approval took effect, the story recounts, Thompson left his job, and five months later he took a paid position on the board of Applied Digital Solutions.

This just doesn't look good for Thompson or for the 2,000 people with RFID chips in their bodies now.

To get a sense of how worrisome this newly uncovered research might be, I asked one of them. Amal Graafstra has put two chips in his own hands voluntarily, but he deliberately avoided the kind approved by the FDA.

Amal Graafstra

Graafstra opens a door by waving his micro-chipped hand near the keypad.

The reason is that he wanted to be able to remove his implants easily for any reason. The "anti-migration" coating on pet and human implant chips makes them much harder to take out.

Graafstra said he strongly suspects it's this coating that caused cancerous cells to grow around the implant sites on the animals in the studies.

"Now I'm just that much more satisfied I chose not to get an 'FDA approved human' or pet implant which have this coating," he writes in his blog. Graafstra manages to provide a good source of do-it-yourself information on RFID, as well as some clear-headed thinking about the science around it.

Could it be that these self-taught "guinea pigs" provide better expertise on the topic than the FDA?