In 1967, James Wood and colleagues published a study on the growth of Japanese adolescents whose pregnant mothers were exposed to the atomic bombs in Hiroshima and Nagasaki years earlier. Of course, many people were killed by the bombs, although estimates vary somewhere between one and two hundred thousand in all. By one estimate, the mortality rate of people within one kilometer of the bomb’s hypocenter in Hiroshima was 86%. This rate dropped to 27% for people who were between 1 and 2.5 km, and to 2% for those between 2.5 and 5km. Comparable numbers were reported for Nagasaki: 88%, 34%, and 11% respectively. This study was about some of the survivors.
In all, the Wood et al. study included 1,259 seventeen-year-olds, who had annual medical examinations since 1950. They were then compared for height, weight, and head circumference by their mother’s distance from the bombs’ hypocenters. They concluded that:
The present study indicates that exposure of the human fetus to the irradiation of the atomic bombs has resulted in limitation of head and body size…Most detectable effects on growth of children who were in utero ATB (at time of bomb) occur within 1,500 meters from the hypocenter. (p. 1378)
For example, Table 3 looked at growth attained at age 17 by distance from the hypocenters while in utero. Both males and females within 1500 meters were noticeably shorter. The trend appears to be stronger for Nagasaki, but sample sizes were much smaller than in the Hiroshima sample (in some of the sub-samples from Nagasaki, there were as few as 36 individuals), so there may more room for random effects.
However, it is still not completely clear that the effects were due solely to prenatal exposure to radiation. For example, a more recent study on the growth of adolescents who were exposed prenatally to the fallout in Chernobyl found that there was no significant effect on stature (Neta et al 2014). I admit that I haven’t done all of my homework here and I don’t know enough about the effects of radiation, but in the case of Hiroshima and Nagasaki it seems plausible that the devastating damage to property, the likely loss of any family wealth from the bombs, and/or psychological stress could also have long-term effects on growth after birth. This doesn’t mean that radiation is harmless — far from it — but when it comes to growth and development, correlation is not necessarily causation.
Basically, it is not so straightforward whether the effects on growth were due to prenatal exposure to radiation alone, or possibly to other postnatal environmental factors. It seems self-evident that an environment devastated by bombs, atomic or otherwise, would not present conditions conducive for a child to grow. For example, Mevlude Akbulut-Yuksel of Dalhousie University conducted an historical analysis on how physical growth of German children was affected by more ‘conventional’ Allied bombings in World War II.
Her approach was a creative one, correlating adult stature with the level of regional destruction (measured in volume of rubble). Her conclusion was that Germans who were school-aged during WWII and who lived in regions with higher levels of destruction from bombing (primarily in the north and west) were about 0.6 inches shorter as adults. They also completed fewer years of schooling, reported lower satisfaction with their health, died younger, and had lower income.
Perhaps the larger lesson is that war consistently creates a suite of conditions harmful to civilian lives, and that this shows up in bodies including in the way that children grow. In both of these cases from World War II, years had passed between the actual time of war (or even a cataclysmic event like an atomic bomb), and the time of measurement, but their effects remained embodied into adulthood.
Akbulut-Yuksel M. 2014. Children of War: The Long-Run Effects of Large-Scale Physical Destruction and Warfare on Children, Journal of Human Resources 49 (3): 634-662. Link
Neta, G., Hatch, M., Kitahara, C. M., Ostroumova, E., Bolshova, E. V., Tereschenko, V. P., … & Brenner, A. V. 2014. In utero exposure to iodine-131 from Chernobyl fallout and anthropometric characteristics in adolescence. Radiation Research 181(3): 293-301. Link
Wood JW, Keehn RJ, Kawamoto S, Johnson KG. 1967. The growth and development of children exposed in utero to the atomic bombs in Hiroshima and Nagasaki. AJPH 57(8): 1374-80. Link