imho - you will always find someone to complain about something. im sure some kid somewhere would try to eat on e and you would be blamed for it... but i like the idea. unless they were to break (and youre right - they are tough to break open - i had to do some for a cub scout ceremony)
As far as I recall, these things are totally non-toxic, and it says so on the package. At least they were when we used to break them open, and put the liquid all over our tongue's in the army. You really need to liven up a GP medium tent at night, you know? I wouldn't recommend this for children though, and they kind of taste bad.
Ok where we ever in the same unit?? Or maybe all us ex army pucks where sick in the mind at times