Ionizing radiation from medical imaging. Average man-made exposure is much higher in developed countries, mostly due to CT scans and nuclear medicine. Natural background radiation comes from five primary sources: cosmic radiation, solar radiation, external terrestrial sources, radiation in the human body, and radon. The background rate for natural radiation varies considerably with location, being as low as 1.5 mSv/a (1.5 mSv per year) in some areas and over 100 mSv/a in others. The highest level of purely natural radiation recorded on the Earth's surface is 90 µGy/h (0.8 Gy/a) on a Brazilian black beach composed of monazite. The highest background radiation
Biological effects of radiation on the epigenome of DNA double strand breaks can lead to cell cycle arrest in somatic cells and cause cell death. Due to its ability to induce cell cycle arrest, ionizing radiation is used on abnormal growths in the human body such as cancer cells, in radiation therapy. Most cancer cells are fully treated with some type of radiotherapy, however some cells such as stem cell cancer cells show a reoccurrence when treated by this type of therapy. Non-ionising radiations, electromagnetic fields (EMF) such as radiofrequency (RF), or power frequency radiation have become very common in everyday life. All of these exist as