Radiation is energy that travels in the form of waves or high-speed particles. It occurs naturally in sunlight and sound waves. Man-made radiation is used in X-rays , nuclear weapons, nuclear power plants and cancer treatment. If you are exposed to small amounts of radiation over a long time, it raises your risk of cancer. It can also cause mutations in your genes, which you could pass on to any children you have after the exposure. A lot of radiation over a short period can cause burns or radiation sickness. Symptoms of radiation sickness include nausea, weakness, hair loss, skin burns and reduced organ function. If the exposure is large enough, it can cause premature aging or even death. You may be able to take medicine to reduce the radioactive material in your body.