REGULAR ARTICLE Hiroshima survivors exposed to very low doses of A-bomb primary radiation showed a high risk for cancers Tomoyuki Watanabe Æ Masaru Miyao Æ Ryumon Honda Æ Yuichi Yamada Received: 24 December 2007 / Accepted: 15 May 2008 Ó The Japanese Society for Hygiene 2008 Abstract Objectives The aim of this study was to compare the risk for cancers of A-bomb survivors in the ongoing life span