Another post. I'll shut up now.
I also find it hard to believe carcinogens could be a huge problem in chips, given the whole thing is coated in sterile glass. Any carcinogens in the mechanics of the chip itself are contained. Also many things are carcinogens. Plenty of the stuff we eat on a daily basis contains them. The makeup us women (and some of you guys :09
wear is full of them.
Some of the preservatives in the pellets many of us feed our parrots are carcinogens. Carcinogen in most cases does not = cancer. It does mean an increased risk though. Sometimes very minor, like mineral oil (yep, that baby oil stuff you use on your kid. It's also allowed to be added to food, believe it or not) to major like asbestos.
In short, pretty much everything contributes to cell damage and cancer in the end.
But back to chipping! It comes down to weighing the pros and cons.
Cons being procedure risk (large needle into a small bird, anaesthetic being used, though both of these are minimal), finding an avian vet, and perhaps cost if you are not financially well off. Possibly other things like carcinogen could be included, but since no ones found a conclusive study on birds with clear results I think this is negligible at the moment.
Pros being a permanent, unmodifiable and non removable and lifelong form of I.D. which can be linked back to you nationwide (and depending on your chip 'ping back' frequency, world wide)
In my case with the high rate of bird theft in my area and because me and Alex travel alot, I decided the benefits of a chip greatly outweighed the small risk involved with the procedure since it gives us the greatest chance of being reunited should anything ever happen.
The procedure itself on a small bird (Alex is a Jenday conure, so this goes for anyone with similar sized bids) involved him being administered with a mild anaesthetic (If the bird cant remember what happened, he just waked up a little sore after all. I think this is important to avoid trauma) and the chip being inserted into the lower portion of the left breast muscle via syringe, pressure is then applied to stem any bleeding. Alex was kept in for observation for an hour, afterwards we were given a call to pick him up. He was happy and had no idea what had just happened apart from a sore spot on his chest. The chipping itself was done by a wonderful avian vet in near my town.
It's not for everyone, but in our case the pros outweighed the cons considering the rampant theft here and the large amount of travelling we do.
I also recommend checking out
Introduction to Aviary Security and Theft Prevention at birdtheft.org on the topic of theft.