Ionising radiation exposure of the population of the United States: NCRP Report No. 160

This report is a long-awaited sequel to NCRP Report No. 93 (published in 1987) and provides a comprehensive re-evaluation of the exposure of the US population to all natural and man-made sources of ionising radiation in 2006—some 25 y after the previous assessment for the early 1980s. Over this period, the average annual effective dose per individual in the US population (EUS) from all sources has increased by a factor of 1.7 to 6.2 mSv, with the increase being almost entirely due to the dramatic growth of relatively high-dose medical imaging procedures using X-rays and radionuclides. The report first considers exposures from ubiquitous background radiation, which contribute 50% of the EUS from all sources (3.1 mSv). They are divided into extra-terrestrial cosmic and solar radiation, terrestrial radiation from surface soil and rocks, internal exposures from inhaled radon and thoron seeping out of the ground and internal...