All amphibian skin is poisonous to a degree.
The major reason for this is to produce a bad taste to a potential predator. Some species of amphibians do have secretions that are toxic to humans and other animals, such as the poison dart frogs and other tropical frogs of the family Dendrobatidae. If you handle one of these toads wash your hands before touching anything that you may put in your mouth or before touching your eyes. It has also been introduced to Hawaii. Bufo alvarius is found mainly in southern Arizona and northeastern Mexico.