Frequently Asked Questions
|5 |What health effects other than
cancer have been seen among the atomic-bomb survivors?
|5 | The Life
Span Study mortality analyses have revealed a statistically
significant relationship between radiation and deaths resulting
from causes other than cancer (see also "Deaths due to non-cancer
disease" in "Radiation Health Effects").
A total of 18,049 non-cancer deaths occurred between
1950 and 1997 among the 49,114 persons with significant
radiation doses. The overall risk for non-cancer deaths is considerably
smaller than that for cancer deaths, but because non-cancer causes
comprise a larger fraction of human deaths overall, the total number
of estimated radiation-related excess non-cancer deaths is about
50-100% of the number of estimated radiation-related cancer deaths
(the reason for the wide range is that the data do not yet clarify
the shape of the dose response, and different estimates of number
of excess radiation-related cases result from various shapes of
response that can be fit to the data).
Clinical researchers conducting the Adult
Health Study of biennial clinical examinations have analyzed
the relationship between radiation exposure and a number of selected
non-malignant (non-cancer) disorders. Statistically significant excess
risks were detected for uterine myoma, chronic hepatitis and liver
cirrhosis, thyroid disease, and cardiovascular disease.
The results suggested that the thyroid gland in young persons may be more sensitive
to radiation not only in the development of thyroid cancer, but
also possibly in the development of non-malignant thyroid disorders.
another condition related to radiation. Symptoms can
appear as early as one or two years following high-dose
exposure and many years after exposure to lower doses.
Some non-cancer diseases may be associated with altered immune functions
in A-bomb survivors. Immunological study of survivors demonstrated
that the proportion of helper T cells was significantly decreased
with increased radiation dose (see "Immunology Studies" of the Department
of Radiobiology/Molecular Epidemiology).
Furthermore, the prevalence
of myocardial infarction was significantly higher in individuals
with a lower proportion of helper T cells. These results suggest
that myocardial infarction in A-bomb survivors is partly due to
defects of helper T cells. Such defects may contribute towards a
reduced immune defense against microbial infections, possibly leading