Technical Report No. 15-73
JNIH–ABCC Life Span Study Report 7. Mortality experience of A-bomb survivors, 1970-72, 1950-72

Moriyama IM, Kato H

Editor’s note: No journal article was published.

Summarｙ
This report updates the mortality status of the JNIH-ABCC Life Span Study cohort by the addition of data for 1971 and 1972, and examines data to see what, if any, changes of significance have occurred since the issuance of the last report. Also presented are data for the entire period of observation, 1950-1972.

There are no new findings of major importance in the data for the current period. Except for a few instances, the data serve to reinforce previously reported findings on the delayed effects of radiation exposure to the A-bombs.

The mortality experience of the Life Span Study cohort continues to be favorable. The death rates for the most recent period are probably the lowest ever recorded in the 22-year history of the study. Except for males 10-19 years of age at the time of the bomb, the current death rates appear to be significantly lower than the corresponding national death rates.

Leukemia continues to show the greatest excess of mortality despite the rapid decline in mortality. For the years 1970-1972, the risk of mortality from leukemia for survivors exposed to 100 rad or more reached a very low level but it is still significant at the 5% level as contrasted with the comparison group 0-9 rad in Hiroshima.

The mortality risk from all malignant neoplasms other than leukemia for the heavily exposed population (200+ rad) is high compared with that for the 0-9 rad group. This is evident in the data for recent years as well as for the period as a whole. However, it does not appear as though the mortality risk for this group of neoplasms is increasing for the cohort of survivors exposed to 100+ rad.

Of interest for the period of observation as a whole is the increased risk in the heavily exposed group to mortality from cancer of the digestive organs other than the stomach. Also, for the recent period, the difference between the mortality ratio for stomach cancer for the 200+ rad group and that of the control group (0-9 rad) is suggestive of statistical significance (P = .096). Thus far, there is no evidence from the pathology studies to implicate radiation exposure as a possible cause of cancer of the digestive organs. Future changes in stomach cancer mortality bear watching.

Mortality ratios for cancer of specific sites are generally subject to considerable variability because of the relatively small number of cases. Accumulation of data for another 2 years will add stability to the mortality ratios and relative risk figures for the current period.

The elevated mortality risk for the residual group of malignant neoplasms in the high exposure group is statistically significant. This group of neoplasms include cancers of specific sites that have been shown to be associated with radiation exposure. However, a large number of deaths in this group is from malignancy of unspecified site.

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.The Life Span Study cohort, 1 October 1950
    2.Person-years at risk 1950-1972
    3.Deaths: All causes
    4.Deaths: Accidents, poisonings, & violence
    5.Deaths: All disease
    6.Deaths: Malignant neoplasms: All
    7.Deaths: Malignant neoplasms: Leukemia
    8.Deaths: Malignant neoplasms: All except leukemia
    9.Deaths: Malignant neoplasms: Stomach
       A. Deaths: Malignant neoplasms: Digestive organs except stomach
  10. Deaths: Malignant neoplasms: Digestive organs & peritoneum
  11.Deaths: Malignant neoplasms: Trachea, bronchus & lung
  12.Deaths: Malignant neoplasms: Respiratory system
  13.Deaths: Malignant neoplasms: Breast (female)
  14.Deaths: Malignant neoplasms: Cervix & uterus
  15.Deaths: Malignant neoplasms: Other
  16.Deaths: Benign or unspecified neoplasms
  17.Deaths: All disease except neoplasms
  18.Deaths: Tuberculosis
  19.Deaths: Vascular lesions of central nervous system
  20.Deaths: Diseases of circulatory system except CNS
  21.Deaths: Other disease
  22.Deaths: Leukemia
  23.Deaths: Malignant neoplasms except leukemia

List of Figures

    1.Relative risk by cause of death, 1950-1972
    2.Mortality ratio by time, deaths from leukemia, 1950-1972
    3.Mortality ratio by age ATB, deaths from leukemia, 1950-1972
    4.M11ortality ratio by age ATB, deaths from all malignant neoplasms except leukemia, 1970-1972
    5.Relative risk by tumors as cause of death, 1950-1972