Yes there are two different types of electromagnetic waves which are both dangerous but different because they both carry different radiation. These two forms of radiation are non-ionising and ionising radiation. Unfortunately, Ionizing radiation is dangerous because they use these types of waves for therapy for different cancers. This type of radiation attacks the bodies cells, not only the cancer cells but often the perfectly healthy white and red blood cells. This has lead to cases of death before which is why this is the most dangerous type of radiation in the electromagnetic spectrum. But don't forget, non-ionising radiation is also dangerous when it is used over a certain amount of times.