Plutonium isotopes refer to the different forms of the radioactive element plutonium, which vary in their number of protons and neutrons. Synonyms for plutonium isotopes include plutonium-238, plutonium-239, and plutonium-240, as well as more generic terms such as radioactive plutonium and plutonium radioisotopes. These isotopes are unstable and emit radiation, making them dangerous to human health and the environment. Plutonium isotopes have been used in nuclear weapons and as fuel for nuclear reactors, but their potential for misuse and the threat of nuclear accidents have led to widespread concern over their use and storage.