Ionising radiation in the form of different types of electromagnetic waves is known as a carcinogen which is a risk factor for cancer. Radioactive materials are a type of ionising radiation. The radiation breaks through the cells and damages the chromosomes which causes mutations in the DNA. The more you are exposed to ionising radiation, the more likely that cancer will develop and mutations will occur. When taken directly into your body, ionising radiation is very dangerous. Breathing in radioactive materials into the lungs enables the ionising radiation to penetrate directly into the cells. Well-known sources of ionising radiation include: Ultraviolet light from the sun - this increases the risk of skin cancers, Radioactive materials found in the soil, water, and air, Medical and dental X-rays, Accidents in nuclear power generation, especially accidents such as the one in Chernobyl, Ukraine.