How harmful are trace amounts of the product inside large-ant capsules for miniature humans?
A pesticide would not be sold for home use if it were harmful to children in trace amounts.  They are generally safe if used correctly. Take for example Maxforce FC Ant Killer Bait Gel, the bait that I often use to control ants.  It uses Fipronil at a concentration of 0.001%.  When I first started using this bait, I was a little freaked out, because I had to order the stuff online.  They didn't sell it in the stores.  Then one day I happened to look at the label of the Frontline Plus flea treatment that I apply liberally to my dog each month. Turns out that it contains 10% Fipronil!  I did some research, and found out that Fipronil is selectivly harmful to insects (I still don't want it on me though).  

Other insecticides are similar.  When applied as instructed, they will not be harmful to humans. The best news is that you don't have to take anyone's word for it.  Each of these insecticides have a Material Safety Data Sheet (MSDS), which will tell you how and in what concentrations the chemicals are harmful to humans.  Just search for the product you are using and "MSDS".