In no other field of scientific investigation does an international mechanism to achieve global consensus exist compared with that specifically set up for estimating health effects attributable to exposure to ionizing radiation. UNSCEAR has, for nearly half a century, annually assembled leading radia­tion specialists to provide the most plausible estimates of the health risks attributable to radiation exposure, and periodically submitted them to the 192 world governments via the UN General Assembly. The extremely detailed UNSCEAR reports on radiation effects are a synthesis of thou­sands of peer-reviewed references. While it is certainly unfeasible to sum­marize accurately such a vast amount of information, the author has made several brief accounts of UNSCEAR estimates aimed at a broad audience (Gonzalez, 2002, 2004b, 2004c).

UNSCEAR’s estimates have not changed substantially over the past years and can be categorized into two types of effects, namely (1) prompt tissue-reactions that are usually termed ‘deterministic’ effects, because they are determined to occur above certain dose thresholds, and (2) long-term late effects, such as cancer, which are termed ‘stochastic’ effects due to the aleatory nature of their manifestation.