My information is that one Phyllobates terribilis contains enough toxins to kill 12 adult humans or 20,000 rats, whatever that means. However in captivity and especially captive bred frogs that aren't being fed the particular tropical ants they eat in the wild, as well as other environmental factors, they lose their toxins in captivity. If you are worried about keeping "poison dart frogs" because of the toxins, the "worst" of them are less dangerous than many toads sold in pet stores. The Phyllobates terribilis is one of the most bold and entertaining frogs to keep. Since he doesn't know he is no longer toxic, he is afraid of nothing, is never shy and seldom stressed out.
I'm not sure why you asked the question, but if you are considering what species to keep, poisoning you is not a concern. You would want to keep your hands off of any of them as much as possible-- for their welfare, not yours.
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
3 D. galactonotus pumpkin orange splash back
5 D. imitator
4 D. leukomelas
4 D. pumilio Bastimentos
4 D. fantasticus pending