If they were swabbing skin on the outside of the body, it would still be bad. But this goes to the thinnest point between outside and inside of your brain, where the scent nerves travel into the brain.
yep putting a brain cancer causing chemical where it is most likely to get into your brain. one test, could be harmless, 50 or 60 of the things, probably harmful, possibly deadly.
Either way, not worth the risk.