A recent Associated Press article in The Washington Post stunned cat and other pet owners who have animals with tracking implants. A series of highly accredited research studies, done over the last decade, have now been brought to light and show the same microchips or RFID (Radio Frequency Identification) devices used to track pets are the cause of fast-growing, malignant cancers in 1% to 10% of lab animals tested. Now animal owners are faced with what to do.

Why Are the Microchips Causing Cancer?

As Dr. Katherine Albrecht, a consumer educator and privacy advocate who helped investigate and break this story, explains what the scientists believe is happening is similar to a common splinter. When you get a splinter in your finger, your body does everything it can to get rid of it. The site gets red, it swells up and attempts to dislodge the foreign object.

However, when a microchip is embedded deep in the fatty tissue of your pet, its body can't push the chip out like a splinter. Instead an inflammation forms around the microchip. Scientists believe these inflamed cells can turn malignant and then metastasize and move around in the body. What's worse is these tumors can be fast-growing and malignant.

What the Research Shows

Between 1996-2006 eight published veterinary and toxicology journals reported that lab mice and rats injected with microchips sometimes had a tendency to develop subcutaneous "sarcomas" or malignant tumors surrounding the implants. Below are a brief summary of the some of the major conclusions.

* A 1998 study in Ridgefield, Connecticut of 177 mice reported cancer incidence to be slightly higher than 10 percent. Researchers described the results as "surprising."

* A 2006 study in France detected tumors in 4.1 percent of the 1,260 microchipped mice. This was one of six studies in which the scientists did not set out find microchip-induced cancer but noticed the results incidentally.

* In 1997 a study in Germany found cancers in 1 percent of 4,279 chipped mice. The tumors "are clearly due to the implanted microchips" the authors wrote.

What the Researchers Are Saying

When Associated Press asked scientists to weigh in on the available research, specialists at some pre-eminent cancer institutions said the findings raised red flags.

--"There's no way in the world, having read this information, that I would have one of those chips implanted in my skin, or in one of my family members," said Dr. Robert Benezra, head of the Cancer Biology Genetics Program at the Memorial Sloan-Kettering Cancer Center in New York.

--Dr. George Demetri, director of the Center for Sarcoma and Bone Oncology at the Dana-Farber Cancer Institute in Boston, agreed. Even though the tumor incidences were "reasonably small," in his view, the research underscored "certainly real risks" in RFID implants. In humans, sarcomas, which strike connective tissues, can range from the highly curable to "tumors that are incredibly aggressive and can kill people in three to six months," he said.

--At the Jackson Laboratory in Maine, a leader in mouse genetics research and the initiation of cancer, Dr. Oded Foreman, a forensic pathologist, also reviewed the studies at the AP's request. At first he was skeptical, suggesting that chemicals administered in some of the studies could have caused the cancers and skewed the results. But he took a different view after seeing that control mice, which received no chemicals, also developed the cancers. "That might be a little hint that something real is happening here," he said.

--"The transponders were the cause of the tumors," said Keith Johnson, a retired toxicologic pathologist, explaining in a phone interview the findings of a 1996 study he led at the Dow Chemical Company in Midland, Michigan.

What Can We Do?

1. Check your microchipped cat or other pet regularly for swelling or lumps, especially around the injection site. If owners or veterinarians find anything abnormal in that area or any other (as the chips may migrate), an x-ray or biopsy should be performed.

2. Dr. Albrecht also suggests pet owners help her volunteer to educate and contact animal advocacy and animal rights groups as well as veterinarian organizations by taking action at her AntiChips.com website. Many of these animal-loving groups endorsed microchipping pets without having access to the studies above. Dr. Albrecht hopes public pressure will also force Verichip Corporation, the manufacturer of the chip, to take responsibility or face a class action lawsuit.

3. Report any incidences of pets who have died of cancer or animals who have been cured of cancer to Dr. Albrecht at AntiChips.com, especially if is known or suspected that the tumor is or was linked to a microchip. This will help further document proof of the cancer and stop microchipping.