Was passing through airport security (Canada) with my 3 month old when I was told we were selected for a "random" search. They swabbed both of our hands. When I objected to her hands being swabbed they just put on a new swab pad. Is this commonplace for babies? What if any chemicals are in the pads? She has her hands in her mouth all the time (I did wash them afterwards with water).
Here is a quote from a page about the actual swabs:
Itemiser swabs are made of Teflon coated fiberglass that are designed to handle the high heats required to collect samples from the traps. Sample traps hold up well to water, heat and use but must be replaced if they are torn or have been contaminated in the collection process.
They are not pre-soaked in anything. Your child is not going to get poisoned by the swab. It is possible that a previous person had a cold, and they reuse the swabs (ew!) so the agent switching to a clean swab was all that was required.
The cotton swabs used in those kinds of procedures are usually sterile and the same suppliers as you would find in a hospital or doctor's office. In a country like Canada, I would expect that those swabs are completely harmless to any individual, no matter newborn or adult.
The swabs are usually used to test for illegal substances(explosives and/or drugs). Here is some info on the machines used.
I had that kind of random search/test done last year September at a german airport as a German citizen (caucasian) so I wouldn't assume any racial profiling.