Taricha newts of western North America are particularly toxic ; the Rough-skinned newt Taricha granulosa of the Pacific Northwest produces more than enough tetrodotoxin to kill an adult human . Taricha newts of western North America are particularly toxic . The Rough-skinned newt Taricha granulosa of the Pacific Northwest produces more than enough tetrodotoxin to kill an adult human , and some Native Americans of the Pacific Northwest used the toxin to poison their enemies .