Over the weekend, the AP's Todd Lewan reported that a series of veterinary and toxicology studies conducted over the past decade or so determined that implanted RFID chips had induced cancerous tumors in mice and rats.

"The transponders were the cause of the tumors," says Keith Johnson, who ran one of the studies for Dow Chemical in 1996.

Canada.com's Bert Hill notes that VeriChip stock plunged 14 percent yesterday as a result of the news.

According to Wired's Kim Zetter, the catalyst for the AP story was an investigation into the death of a bulldog named Leon from a tumor attached to an ID chip in his neck. Researchers looking into Leon's tumor determined that other studies in the past had found tumors occurring in cats that had been microchipped. "The tumors formed between 1 month and 3 years after the chips were implanted and seemed to spring up around areas of inflammation created by the microchip," Zetter writes.

Lewan raises troubling questions about why these studies were ignored when the FDA approved the VeriChip, and to what degree Tommy Thompson, who as a board member was the happy recipient of a gift of hundreds of thousands of shares of VeriChip stock, may have been involved...

More here from The Register ... more here from The Inquirer ... more here from The Motley Fool ... and VeriChip's response is here.