RP 4-10

Longitudinal clinical ctudy of the F1 offspring of A-bomb Survivors


Rationale: The heritable effects of exposure to ionizing radiation have long been a public health concern. However, there are no human data on the potential risk of adult-onset multifactorial diseases in the offspring of exposed persons. This longitudinal clinical study of the F1 offspring of A-bomb survivors will provide the first information on this important issue.

Objectives: The objectives of the Longitudinal Clinical Study of the F1 Offspring of A-bomb Survivors (F1 Clinical Study) are (1) to elucidate the effects of parental exposure to A-bomb radiation on the development of multifactorial diseases and subclinical conditions among the F1 offspring of A-bomb survivors, (2) to increase the precision and reliability of risk assessments, (3) to preserve biological samples for future research studies, and (4) to contribute to the health and welfare of the F1 population via health examinations and health guidance.

Methods: This prospective study will conduct periodic health examinations of a fixed cohort of F1 offspring born to A-bomb survivors between 1946 and 1984. In the initial F1 health effects study, 14,175 people indicated they were potentially willing to undergo health examinations among the 16,789 subjects of mail surveys who responded to questionnaires concerning health and living habit by mail or telephone between May 2000 and November 2008. Of those, 11,984 actually attended the Radiation Effects Research Foundation (RERF) clinic for an examination by the end of November 2008. After excluding 397 of the 14,175 because of subsequent death or contact refusal and 1,320 with currently unknown addresses, a total of 12,458 are potentially eligible.

The F1 Clinical Study with health examinations will be carried out every four years. First, brochures on outline of the health examination will be sent to all subjects, and secondly, participation in a clinical study will be requested by telephone contact. A letter explaining the health examination and samples of informed consent forms will be sent in advance to those who express a desire to participate in the health examination. In the F1 Clinical Study, upon obtaining informed consent from the participant, the health examination will include a sociodemographic, lifestyle and medical-history interview, physical examination, anthropometric measurements, blood pressure measurements, electrocardiogram (ECG), urinalysis, blood/biochemical tests, stool occult blood test, abdominal ultrasonography, chest X-ray examination, and so on. Multifactorial diseases such as hypertension, hyperlipidemia, diabetes mellitus, ischemic heart disease, and stroke detected via these examinations will be analyzed in relation to radiation exposure of their parents, taking into consideration confounding factors. Blood and urine taken from those who gave their consent will be preserved for future research studies.

The F1 Clinical Study will contribute to the health management and welfare of the F1 offspring of A-bomb survivors by feeding back the results of the health examination, providing appropriate health guidance, and providing an outside medical referral if necessary.

The procedures and contents of the health examination, the ethical issues, data management, and so on are generally similar to the previous F1 Clinical Study (FOCS). Future research studies using stored biological samples will be conducted after a separate detailed research protocol is prepared and approved by the usual RERF procedures.