Overview of RERF Research Programs

The principal focus of the RERF research program is the study the effects of radiation in the survivors of the atomic bombings of Hiroshima and Nagasaki. Several fixed cohorts or sub-cohorts were established to provide epidemiological and clinical data on the health status and mortality of the survivors and their children. Laboratory-based research studies in the fields of radiobiology, immunology, genetics, and molecular epidemiology are carried out to help interpret the various findings and contribute to the understanding of the mechanisms of disease induction.

Life Span Study

The Life Span Study consists of a large cohort from a general population of both sexes and all ages. It encompasses a wide range of accurately known doses and incorporates accurate disease incidence and mortality recording and careful evaluation and reporting of results. These features make this the most informative epidemiological study in the world for establishing radiation risks. There is a commitment to continue the follow up for the complete lifetimes of all participants. Risks are evaluated for cancer incidence, cancer mortality, and non-cancer effects in relation to radiation dose.

Adult Health Study

The Adult Health Study is a clinical study of a sub-cohort of the Life Span Study. Examinations of atomic-bomb survivors are conducted every two years, providing a continuing health profile of an aging population. This study primarily identifies radiation-related risks of diseases other than cancer and examines aging and radiation-related physiological changes. Furthermore, blood and urine samples are collected and stored with the consent of the examinees for future research on cancer and non-cancer diseases. This study will continue throughout the lifetimes of the survivors to accurately quantify the association between radiation and cancer and non-cancer disease risks.

Children of Atomic-bomb Survivors (F1) Study

The children of the atomic-bomb survivors are being studied to determine whether genetic effects might be apparent that could be related to parental exposures. An initial study of birth defects did not reveal any discernable effects. Subsequently, studies on mortality and cancer incidence, chromosome abnormalities, and serum proteins were also conducted, but again no radiation effect has been observed. Presently, continued mortality and cancer-incidence follow-up and molecular studies on DNA are being conducted. Starting from 2002, a new clinical study was initiated to investigate lifestyle-related diseases that are not observable at birth but start to appear after middle age (e.g., hypertension, diabetes mellitus, etc.). This study was conducted to examine over a period of four years about 12,000 people whom we have contacted with the cooperation of the Second-generation A-bomb Survivors Council and whose willingness to be examined was confirmed. Please refer to the following report on the results of the above-mentioned study:
Report on the Health Effects Study of the Children of A-bomb Survivors (March 2007)[PDF: 429KB]
The clinical study (health examination) of the children of A-bomb survivors has been continued since November 2010 with about 12,000 people, almost the same participants from the previous study.

In Utero Study

The in utero study is a unique evaluation of the lifetime health experience of a specially exposed population, namely those in utero at the time of the bombings (about 3,600 persons). It is not known whether the sensitivity to radiation effects of this group is similar to or greater than that of the youngest postnatal group (0-5 years). The continued follow-up of this cohort through middle and old age until mortality will be highly informative.

Radiation Biology

Radiation biology studies are directed at understanding the complex result of physical phenomena (location, type and amount of energy deposition), biological reactions (damage consequences, repair, adjustment processes) and endogenous factors (age, sex, hormones, diet) involved in radiation response. Investigations are specifically directed to DNA indications that cause or predispose to breast cancer and to thyroid cancer. Speciallized techniques are applied to blood or tissue samples in order to distinguish changes in DNA that may have occurred as a consequence of radiation exposure.


Evidence is emerging that atomic-bomb radiation led to certain changes in the immune system of exposed persons. State-of-the-art methods used to characterize cells of the immune system are being applied to better understand these changes and to assess their possible impact on health.

Molecular Epidemiology

Radiation-induced effects not readily apparent in the body (i.e., at the phenotypic level) may be discernable from molecular changes in DNA (i.e., at the genotypic level). This newly emerging field is being pursued at RERF. Serum collected within the clinical program or tissue obtained from autopsies and surgeries conducted on members of the epidemiological follow-up program are studied in an attempt to better understand the mechanisms and causes of disease.


The cytogenetics evaluations provide a means of assessing radiation exposure (biological dosimetry) by evaluating the types and amounts of structural damage in chromosomes.


Statistical analyses provide the means to assess relationships between risk factors and disease in the face of the variability inherent in data on disease rates or other health effects. The basic activity of this program concerns risk assessment through application of mathematical models to rates of disease occurrence or death in order to identify and quantify radiation effects. In addition, RERF statisticians collaborate with other RERF scientists on study design and data analysis and conduct methodological research to develop better methods for the analysis of data on disease and health risks.

Atomic-bomb Dosimetry

Assessing the risks of radiation exposure requires knowledge of the dose of radiation received. There are no direct measurements of dose for individual survivors. This program is concerned with providing survivor dose estimates. Basic information on radiation exposures are based on modern understanding of the physics of the bombs and the results of extremely sensitive measurements that can detect minute traces of the A-bomb radiation exposure in various types of materials (concrete, granite, copper, etc.). In order to estimate the dose received by an individual survivor, this information is combined with historical interview data pertaining to that survivor’s location and shielding at the time of the bombs. The dosimetry program is also concerned with developing a better understanding of the uncertainties in survivor dose estimates and how to account for the effect of these uncertainties on risk estimates.