I don't think it pays to be paranoid about the motivations of vets; yes, they are paid to take care of sick animals and do routine procedures like putting in microchips and vaccinating, but they got into the field because they like animals. Being skeptical that veterinary associations promote microchipping because their members get money from microchipping is like being skeptical that the American Heart Association promotes cholesterol testing and blood pressure because the clinics of their members get money from that. Yes, if all illnesses were cured, all medical professionals would be out of a job, but that doesn't mean they are all trying to make us ill.
Especially in human medicine there are serious problems with over-treatment, but those are cultural and expectation related, not because of greed on the part of medical practitioners and medical associations (sometimes because of greed on the part of device and pharmecudical companies, but I'm not asking you to believe what the chip manufacturing companies claim). It pays to be skeptical, but it does not pay to spend time looking for conspiracies. If there is a conspiracy, simple look-at-the-evidence skepticism will uncover it.
Pet "microchips" are passive Radio Frequency IDentification (RFID) chips encapsulated in glass. They don't emit any energy or do anything; they simply have a number encoded in them. When an animal is "scanned" for a microchip, the scanner emits radio waves, and the energy in the radio waves powers the RFID chip which transmits its number to the scanner.
Getting annual booster vaccines is much, much more dangerous to your cat than getting a microchip. The World Small Animal Veterinary Association says, in its 2007 vaccine guidelines "Vaccines should not be given needlessly. Core vaccines should not be given any more frequently than every three years after the 12 month booster injection following the puppy/kitten series." and has the take-home message about vaccines "We should aim to vaccinate every animal, and to vaccinate each individual less frequently." I promise you, annual vaccines is more of "profit motive" item than once-per-lifetime microchipping, and the WSAVA does not support annual vaccines while it does support microchipping.
From the WSAVA webpage that BLAISE linked
|Many millions of companion animals have subsequently been implanted around the world with a tiny proportion reporting any type of problem. In the UK where there has been an informal reporting system for adverse reactions for over ten years only two of the 3.7 million implanted animals recorded on the Petlog database have been reported as developing a tumour at the site of implantation. In one of these cases the pathologist reported that the transponder was incidental to the tumour formation. Overall, the Committee is aware of less than ten reports of tumours forming in companion animals associated with an implanted microchip.
6) Millions of animals have carried their transponders for most of a natural life time without any adverse effects.
That's a reported incidence of 1 out of 3.7 million.
Animal Care & Use Review committees at universities which oversee animal research and try to prevent and mitigate animal harm, strongly advocate the use of RFID chips in animal research, because it doesn't hurt the animals. Researchers use RFID chips constantly, and apparently some cancer-prone strains of mice got cancers directly around the microchips. Researchers still use these chips because they are a really safe and animal friendly (less disruptive to the animals that ear tagging). If causing cancer was a serious risk, researchers wouldn't use this method of identification.
The AP story seems like it's more worried about one former FDA head and his apparent corruption (going into related private sector work directly after his work in the public sector) than about the science of cancer and implants, much less the science of cancer and implants in cats.
Just as an aside, having watched tattooing and done microchipping (the tattooing on a human friend, the microchipping on reptiles), even if vets use local anesthetic for tattooing (we don't for humans: do we for cats?), I think it's a much less pleasant experience for the animal than the quick in & out microchip insertion.
To conclude: microchipping is not a serious risk.