Can mold on bread be killed with heat so it is safe?

While heating up moldy bread can kill the mold, it does not make the bread safe to eat. The roots of mold can grow deep into the bread, making it impossible to kill all the mold spores with heat alone. Some molds also produce mycotoxins, which are harmful substances that can cause illness even after the mold has been killed. For these reasons, it is important to discard moldy bread rather than trying to salvage it by heating it.