Radiation Risk of Mortality of Cancer and Noncancer Diseases in the Atomic-bomb Survivors

Ozasa, Kotaro

Radiation Risk of Mortality of Cancer and Noncancer Diseases in the Atomic-bomb Survivors

Monday, 18 August 2014

Exhibit hall (Dena'ina Center)

Kotaro Ozasa, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Yukiko Shimizu, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Truong-Minh Pham, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Eric J Grant, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Ritsu Sakata, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Hiromi Sugiyama, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Atsuko Sadakane, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

Midori Soda, MD , Radiation Effects Research Foundation, Nagasaki, Japan

Kazunori Kodama, PhD , Radiation Effects Research Foundation, Hiroshima, Japan

INTRODUCTION: Late health effects of atomic-bomb radiation have been evaluated by long-term cohort studies.

METHODS: The Life Span Study (LSS) is a cohort of 120,321 atomic bomb survivors, who have been followed up for mortality since 1950. Individual radiation doses were estimated as weighted absorbed doses (Gy), gamma dose + neutron dose x 10, based on location and shielding at the time of the bombing. Excess relative risk per unit dose (ERR) has been calculated.

RESULTS: A significantly increased risk of radiation for solid cancer mortality was estimated at doses ≥ 0.20 Gy (ERR/Gy=0.42 at age 70 years after exposure at age 30) based on a linear model, which was the best fitting model. The ERR/Gy was 0.17 for all noncancer respiratory diseases (NCRD), 63% of which consisted of pneumonia/influenza. The dose response of NCRD was more concave in the early period of observation and became linear in the late period. In addition, adjustments for indications of cancer and/or cardiovascular disease decreased the risk estimates of all NCRD by 35% from 0.17 to 0.11.

CONCLUSIONS: The long-term risk of radiation for cancers is well established. However, the apparent association between NCRD and radiation exposure may, in part, be attributed to coincident cancer and/or other diseases that were associated with radiation risks. The different shapes of the dose response by observed period suggests different mechanisms of radiation risks.

RRFERENCE: Ozasa K, et al. Studies of the Mortality of Atomic Bomb Survivors, Report 14, 1950-2003. Radiat Res 2012;177:229-43. Pham TM, et al. Radiation exposure and the risk of mortality from noncancer respiratory diseases in the Life Span Study, 1950-2005. Radiat Res 2013;180:539-45.