The various anthropometric data on the Rongelap children
have been tabulated periodically in annual reports,’’ and
ongoing analyses have also been published in the literature.*”
Beginning several years after exposure it was noted that, for
boys, the statural growth curve for the exposed group lagged
behind the curve for the unexposed group. This lag appeared
to be due primarily to the slowed growth in the group of boys
exposed at <5 years of age. It was first thought that the growth
retardation might be a direct radiation effect,® but, as noted,
findings established radiogenic hypofunction of the thyroid
gland asits cause.
Assessment of the pattern of growth and development of
the individuals who were children (<18 years old) on March
1, 1954, has been a consistent componentof the pediatric examinations of the Rongelap people. Data interpretation has
been complicated by radiation injury to the thyroid gland,
partial or total thyroidectomies in the children who developed thyroid abnormalities, and administration of TSH suppressive doses of thyroid hormone to the exposed Rongelap
population since September 1965 (when the youngest exposed child was 11 years old).
Analyses presented here are limited to the Rongelap Atoll
population.
Methods
In 1957, the population repatriated to Rongelap included
{in addition to the exposed returnees) a sizable number of
children who had not been exposed to fallout radiation. Some
were Rongelap natives who had been awayat the timeof fallout, and others were relatives of residents. Since these children were of the same stock (blood relations) and would live
postreturn under the same environmental conditions as did
the exposed population, they were selected as unexposed
controls. During 1957, 1958, and 1959, the control population
was carefully characterized. Examinations conducted on these
children were the same as those conducted on the exposed
population.
From the very first examination, growth data have been recorded. During the first three years, the measurements consisted of weight, standing height, sitting height, length of upper extremity, arm span, biacromiai width,intercristal width,
head circumference, abdominal circumference, andleft calf
circumference. In 1958, the battery of body measurements
was standardized to include weight, stature, sitting height,
head circumference, head width, head length, chest circumference, chest width, chest depth, buttock circumference, left
calf circumference, biacromial diameter. and bicristal diameter. Standardized techniques '*'* were used. Thestatus of secondary sex characteristics was evaluated by inspection with
the method described by Greulich et al,*'* Reynolds and
Wines**** and Shuttleworth.’ History of menarchein girls,
penile and testicular development in boys, hair distribution, and breast development were recorded during these
examinations.
In 1958, apparent discrepancies regarding birth dates were
noted in the charts of many children. The absence of recorded
92
THE CANCER BULLETIN, VOL 34, NO 3, 1982
birth information in the Marshall Islands seriously complicated the verification of ages. Detailed genealogic and biologic
histories were compiled for the Rongelap population in
1958-1960. The reconstruction of birth chronologies was
based on intensive evaluation of frequently contradictoryinformation derived from the following sources: (1) dates of
birth reported by parents; (2) dates of birth recorded occasionally in ledgers kept by the village magistrate; (3} limited
numberof birth certificates {not always accurate) on file at the
courthouse in Majuro; (4) birth order of children within each
family unit; (5) ranking of childhood population in terms of
age by parents; and (6) ranking of childhood population in
terms of age by the children (particularly age peers), by relatives, and by friends living in the village.
A table of most probable birth dates was derived for the
Rongelap childhood population. Biologic compatibility of the
birth dates within each family was carefully checked, and the
compatibility of physiologic status with age was also determined for each chiid. The presumptive dates of birth have
been used in the calculations of chronologic ages for analyses
of growth and development.
Roentgenographic documentation of osseous maturation
(x-rays of the left hand and wrist) was initiated in the exposed
children in 1957. A major effort was made in 1958 to examine
the skeletal maturation of exposed and unexposed children.
Unfortunately, these valuable base-line films were lost at sea
during transport. This created a gap of almost three years
whenno radiographs were available on a numberof children
in the spurt phase of growth. Thereafter, roentgenographic
studies of the left hand and wrist were included at irregular
intervals. These were particularly difficult under field conditions and presented manytechnical problems, but the minimal
numberof roentgenograms eventually obtained permitted a
reasonable assessment of the longitudinal skeletal development of each child through the chronologic age of 16 or 17
years in the girls and 18 in the boys.
Skeletal age determinations were made byinspection with
the techniques and standards published by Greulich and
Pyle.'* Early analyses of the skeletal age data were included in
the reports of previous surveys.’ Comparisons between the
exposed and unexposed children were made primarily in the
group who were <10 years old on March 1, 1954. This group
was further subdivided into two categories: those <5 years
old on March 1, 1954, and those aged 5 to 10.
The data on children >10 years old on March 1, 1954,
could not be analyzed in detail. The numberof children (par-
ticularly in the exposed group) in each age category was extremely small, and by the time satisfactory roentgenograms
wereobtained for most of them (1961 to 1963), even the youngest membersof this group were already approachingskeletal
maturity.
Statural Growth
Detailed data are given elsewhere.’ Three age groupings
were used: 0 to 5. 5 to 10, and 10 to 18 vears of age as of March
1, 1954. The two younger groups were combined (age 0 to 10)
for some of the analyses. The numbers of exposed subjects in
the 10- to 18-year-old age groups were extremely small.
Figure 1 shows that there was a consistent retardation of
30 |
fra
Growth and Development Studies
of Rongelap Children
L,1
4
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