Blue kryptonite is toxic only to Bizarro creatures.
Blue Kryptonite: The result of using Professor Potter's "duplicator ray" on some Green Kryptonite. Pre-Crisis, blue kryptonite affected only Bizarros, and in a manner similar to that of green kryptonite on Kryptonians. Post-Crisis, blue kryptonite makes Bizarros become coherent, polite and goodhearted; it also alters Bizarros' distinctive grammar, so that a Bizarro would say "I am Bizarro" instead of "Me am Bizarro". In the Superman Batman comics #25, Bizarro puts on Batzarro's blue kryptonite ring and receives a 12th level intellect.
