Changes in the pattern of growth in stature related to prenatal exposure to ionizing radiation

Purpose: To examine the pattern and spurt in growth and development of pren atally exposed atomic-bomb survivors and to determine whether a statistical ly significant radiation-related growth retardation exists. Materials and methods: The stature of 1566 individuals exposed prenatally t o the atomic bombings has been employed to study the effect of such exposur e on growth. Among these survivors, 30 were severely mentally retarded, and 66 individuals on whom no physical measurements between ages 9 and 19 exis t were excluded from this study. Thus this analysis rests on the measuremen ts obtained on 1470 survivors 9 to 19 years of age at the time of examinati on. Results: When the greater than or equal to 0.50 Sv group was compared to th e other two prenatally exposed groups, a significant retardation of growth was observed only among those survivors exposed in the first trimester of g estation. The onset of the growth spurt among males in the three exposure g roups was at approximately the same age, 11.34 years, but this was not true in females. The maximum velocity in growth for males was at 14.38 years of age, but for females no clear peak velocity was demonstrable. Conclusion: A radiation-related growth retardation was demonstrable in this longitudinal study of the stature of individuals prenatally exposed. It is further demonstrated that among these survivors the growth velocity was fa ster in the high-dose group than in the low-dose group for both males and f emales.