The main goal for the IAEA (International Atomic Energy Agency) is to propagate atomic energy. This is stated clearly in paragraph 2 of the IAEA statute:
"The Agency shall seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world."Moreover, many UN agencies are subordinate to the IAEA. This particularly applies to the World Health Organization (WHO). On the strength of an agreement signed on 28 May 1959 (WHA 12-40), the IAEA can veto any research carried by WHO which would be in opposition to implementation of paragraph 2 of the IAEA statute. One statement in this agreement reads:
"It is recognized by the World Health Organization that the International Atomic Energy Agency has the primary responsibility for encouraging, assisting and coordinating research on, and development and practical application of, atomic energy for peaceful uses throughout the world without prejudice to the right of the World Health Organization to concern itself with promoting, developing, assisting, and coordinating international health work, including research, in all its aspects."So it's easy to assess the relative value of reports about the effects of nuclear disasters published by the pro-nuclear institutions, including the famous 2005 report on Chernobyl (a favorite reference for pro-atomic lobbyists). In short, in the interest of "encouraging, assisting and coordinating research on, and development and practical application of, atomic energy" such reports are very probably biased and tend to downplay the extent of the radiation danger to people.