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|
Birth defects among the children of atomic-bomb survivors (1948-1954) |
No statistically significant increase in major birth defects or other untoward
pregnancy outcomes was seen among children of survivors. Monitoring of
nearly all pregnancies in Hiroshima and Nagasaki began in 1948 and continued
for six years. During that period, 76,626 newborn infants were examined
by ABCC physicians. When surveillance began, certain dietary staples were
rationed in Japan, but ration regulations made special provision for women
who were at least 20 weeks pregnant. This supplementary ration registration
process enabled the identification of more than 90% of all pregnancies
and the subsequent examination of birth outcomes.
Physical examination of newborns during the first two weeks after birth
provided information on birth weight, prematurity, sex ratio, neonatal
deaths, and major birth defects. Newborn frequencies of untoward pregnancy
outcomes, stillbirths, and malformations are shown in Tables 1, 2, and
3 according to parental dose or exposure. The incidence of major birth
defects (594 cases or 0.91%) among the 65,431 registered pregnancy terminations
for which parents were not biologically related accords well with a large
series of contemporary Japanese births at the Tokyo Red Cross Maternity
Hospital, where radiation exposure was not involved and overall malformation
frequency was 0.92%. No untoward outcome showed any relation to parental
radiation dose or exposure.
The most common defects seen at birth were anencephaly, cleft palate, cleft
lip with or without cleft palate, club foot, polydactyly (additional finger
or toe), and syndactyly (fusion of two or more fingers or toes). These
abnormalities accounted for 445 of the 594 (75%) malformed infants in Table
3.
Since many birth defects, especially congenital heart disease, are not
detected in the neonatal period, repeat examinations were conducted at
age eight to ten months. Among the 18,876 children re-examined at that
age, 378 had one or more major birth defect (2.00%), compared with 0.97%
within two weeks of birth. Again, there was no evidence of relationships
to radiation dose.
|
|
Table 1. Untoward pregnancy outcomes (stillbirths, malformations, and neonatal
deaths within two weeks of birth) among A-bomb survivors, by parental radiation
doses and cases/children examined, 1948-1953
|
|
Mother's weighted dose (Gy)
|
Father's weighted dose (Gy) |
| <0.01 |
0.01-0.49 |
≥0.50
|
|
|
<0.01
|
2,257/45,234
(5.0%)
|
81/1,614
(5.0%) |
29/506
(5.7%) |
| 0.01-0.49 |
260/5,445
(4.8%)
|
54/1,171
(4.6%) |
6/133
(4.5%) |
| ≥0.50 |
63/1,039
(6.1%)
|
3/73
(4.1%) |
7/88
(8.0%) |
|
|
|
Table 2. Stillbirths to A-bomb survivors by cases/children examined, 1948-1953
|
|
Mother's exposure
conditions
|
Father's exposure condition |
| Not in cities |
Low to middle doses |
High dose
|
|
|
Not in cities
|
408/31,559
(1.3%)
|
72/4,455
(1.6%) |
9/528
(1.7%) |
| Low to middle doses |
279/17,452
(1.6%)
|
139/7,881
(1.8%) |
13/608
(2.1%) |
| High doses |
26/1,656
(1.6%)
|
6/457
(1.3%) |
2/144
(1.4%) |
|
|
|
Table 3. Malformations diagnosed within two weeks of birth by
cases/children examined, 1948-1953
|
|
Mother's exposure
conditions
|
Father's exposure conditions |
| Not in cities |
Low to middle doses |
High doses
|
|
|
Not in cities
|
294/31,904
(0.92%)
|
40/4,509
(0.89%) |
6/534
(1.1%) |
| Low to middle doses |
144/17,616
(0.82%)
|
79/7,970
(0.99%) |
5/614
(0.81%) |
| High doses |
19/1,676
(1.1%)
|
6/463
(1.3%) |
1/145
(0.7%) |
|
|
| In addition, a clinical health study of about 12,000 individuals was conducted
between 2002 and 2006 with a focus on lifestyle diseases, based on the
idea that adulthood is when disorders from radiation effects may develop.
In this study, possible relationships between parental exposure and a combination
of six multifactorial diseases (e.g., diabetes and hypertension) were analyzed,
taking into consideration such lifestyle habits as drinking and smoking.
The results showed no evidence at this time of increased risk of these
multifactorial diseases among the target individuals. However, given that
the subjects were still young at the time of the health examinations, with
an average age of 48.6, it would be desirable to continue the clinical
health study of this fixed cohort. |
|
References about this subject
 |
Neel JV, Schull WJ, eds. The Children of Atomic-bomb Survivors: A Genetic
Study. Washington DC: National Academy Press; 1991 |
|
Nakamura N: Genetic effects of radiation in atomic-bomb survivors and their
children: Past, present and future. Journal of Radiation Research (Tokyo)
2006; 47(Suppl):B67-73 |
|
Otake M, Schull WJ, Neel JV: Congenital malformations, stillbirths, and
early mortality among children of atomic bomb survivors: A reanalysis.
Radiation Research 1990; 122:1-11 |
|
Fujiwara S, Suyama A, Cologne JB, Akahoshi M, Yamada M, Suzuki G, Koyama
K, Takahashi N, Kasagi F, Grant EJ, Lagarde F, Hsu WL, Furukawa K, Ohishi
W, Tatsukawa Y, Neriishi K, Takahashi I, Ashizawa K, Hida A, Imaizumi M,
Nagano J, Cullings HM, Katayama H, Ross NP, Kodama K, Shore RE. Prevalence
of adult-onset multifactorial disease among offspring of atomic bomb survivors.
Radiation Research 2008; 170:451-7 |
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