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
International Commission on Non-Ionizing Radiation Protection medicine, physics and dosimetry and optical radiation. Its members are scientists employed typically by universities or radiation protection agencies. They do not represent their country of origin, nor their institute and can not be employed by commercial companies. ICNIRP is widely connected to a large community working on non-ionizing radiation protection around the world. Its conferences and workshops are widely attended. ICNIRP presents its draft guidelines online for public review and comment before publication. It has ties to IRPA and is formally recognized by the World Health Organization (WHO) and the International Labour Office (ILO) as partners in the field