One reason HMIP and MAFF gave for allowing the tests was that the radiological impact of the emissions from testing the plant would be very small, less than 0.001 per cent of the average dose received by the British population from natural background radiation. (newscientist.com)
A typical nuclear medicine procedure may impart a radiation dose to the patient comparable to about one to four years of natural background radiation depending on the type of study.1 As with X-rays, the value of diagnostic imaging is great and the risks are negligible compared to the health benefits of having the procedure. (snmmi.org)
Still, there are parts of the world — in Guarapari, Brazil for example — where natural background radiation levels are even higher. (sciencemag.org)