Technical Report No. 1-92

Adult Health Study Report 7. Noncancer disease incidence in the atomic-bomb survivors, 1958-86 (examination cycles 1-14)

Wong FL, Yamada M, Sasaki H, Kodama K, Akiba S, Shimaoka K, Hosoda Y

 

Editor’s note:

The following journal article, based on this RERF technical report, was published in the scientific literature:
Wong FL, Yamada M, Sasaki H, Kodama K, Akiba S, Shimaoka K, Hosoda Y: Noncancer disease incidence in the atomic bomb survivors: 1958-1986. Radiat Res 135:418-30, 1993

Summary

Using the longitudinal data of the Adult Health Study (AHS) cohort collected during 1958-1986, we examined for the first time the relationship between exposure to ionizing radiation and the incidence of 19 selected nonmalignant disorders. Diagnoses of the diseases were based on general laboratory tests, physical examinations, and histories taken during the biennial AHS examinations. The outcomes were encoded as three-digit International Classification of Diseases codes in the AHS database, which served as the basis for case ascertainment. Because accurate information on disease onset time is unattainable for individuals with the diseases of interest, onset times were estimated to be the midpoint between the date of the AHS examination when the disease was initially reported and the date of the previous disease-free examination. The most-applicable organ dose from the Dosimetry System 1986 was used. Tests of dose effects were performed assuming a linear relative-risk model with stratified background incidence.

Statistically significant excess risk was detected for myoma uteri, chronic hepatitis and liver cirrhosis, and thyroid disease, defined broadly as the presence of one or more of certain noncancerous thyroid conditions. The finding for myoma uteri might be additional evidence indicating that benign tumor growths are possible effects of radiation exposure. Our results suggesting the susceptibility of the liver to radiation are consistent with the recent Life Span Study (LSS) report of increased mortality from liver cirrhosis in the heavily exposed group. An age-at-exposure effect was detected in nonmalignant thyroid disease, with increased risk for those exposed at ages less than or equal to 20 yr, but not for older persons. Thus, the AHS data also suggest that the thyroid gland in young persons is more radiosensitive not only to the development of thyroid malignancies, as shown in the most recent LSS report on cancer incidence, but also possibly to the development of nonmalignant disorders. Our findings hold independent of the dose effects observed for thyroid malignancies.

No significant dose-response relationships were detected in any of our cardiovascular disease endpoints. However, the incidence of myocardial infarction appears to be increased among survivors exposed when younger, especially during the last few years of the study period, which is not unlike the trends seen in other studies. Since case ascertainment in the AHS was limited to only 77 nonfatal cases, small sample size cannot be ruled out as an explanation of the current nonsignificant results.

Our analysis also suggests that new occurrences of lens opacity during 1958-1986 are not increased with radiation dose among the AHS participants.

Our results emphasize the utility and importance of the AHS in searching for the effects of acute exposure to ionizing radiation in noncancer diseases. The results provided herein should call attention to disorders that merit more-detailed investigations and should serve as impetus for additional studies.

 

 

Editor’s note: 

The following components of this report contain data on communicable disease frequencies, allergies, malignancies, and many other symptoms that may be of interest from a public health standpoint.

 

List of Tables

1. Nineteen noncancer diseases and their corresponding International Classification of Diseases (ICD) codes
2. Sources of information for disease diagnosis
3. a. Distribution of the Adult Health Study (AHS) subjects by examination participation status, AHS cycles 1-14
   b. Distribution of the 9641 Adult Health Study (AHS) participants by age at the time of bombings (ATB)
4. Distribution of the 9641 Adult Health Study (AHS) subjects by Dosimetry System 1986 (DS86) categories, total kerma (mean ± SD: 0.49 Gy ± 0.86)
5. Number of disease cases and observed background incidence
6. Summary measures of dose response in 19 noncancer diseases, Hiroshima and Nagasaki, both sexes, incidence between 1958 and 1986
7. Effect modifiers in the three noncancer diseases exhibiting a significant dose-response relationship by effect modifiers
8. Estimated relative risk (RR) at 1 Gy for cataract, stroke, and myocardial infarction by effect modifiers

List of Figures

1. Schematic diagram for estimating the disease onset time in a sample follow-up of Adult Health Study (AHS) subjects
2. Observed and fitted relative risks (RR), with 95% confidence bounds for observed relative risk in diseases with a significant dose-response relationship
3. Estimated relative risk of thyroid disease for subjects age 20 yr or less at the time of the bombings (ATB), over 20 yr ATB, and all subjects combined