This link gives a good description of what is toxic levels. It's related to birds but gives more info really in relation to dogs and cats.
It would seem that only a drop here and there would cause no ill effects unless your kitty decides to really lap up a good strong amount of it in excess. I would still express caution if he seems to have that strong of a like for it though, but just a drop here and there I wouldnt be too awfully worried. Could be worse I have to hide the "bleach" around here or if any on my hands from dishes or laundry mine attempts to devour my hands. Particularly if using for floors. He'll actually try to lick the floor to get it. I have to lock him up till it drys.