This publication, the first of two volumes of scientific annexes, provides a detailed review of scientific material that underpins the Committee’s evaluation of the radiation doses and effects due to the accident which occurred at the Fukushima Daiichi nuclear power station on 11 March 2011. It covers the amount and composition of radioactive material released to the environment, the pattern of dispersion and deposition of the radioactive material over land and sea, the radiation doses received by the general public and workers, the radiation effects on the environment, the radioactivity in foodstuffs and the implications of the radiation exposures for human health and the environment. The evaluation uses information provided before the UNSCEAR 60th session (May 2013) by 26 United Nations Member States and 5 international organizations, as well as peer-reviewed literature.