SUS REPRINT NOD AZ A cong tur sanoep grertne:
WSTUIGIE OF THE NOM EMG“Weprinded WomSotedeeSuly'Rs, 1967, Vol. 157, No. $787, pages 445-447
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years after their exposure to radiation
from fallout in 1954, show: chromosome-type aberrations in 23 of 43 ex-
posed persons. Half the aberrations
are of the exchange type. An unexpectedly large number of acentric frag-
ments, but no exchange-type aberrations, appear in a few unexposed people
on the same island,
Chromosome aberrations in blood
lymphocytes have been demonstrated in
several population groups exposed to
ionizing radiation, including patients
during and after radiotherapy for
ankylosing spondylitis (7) or malignant
tumors
(2),
persons
exposed during
diagnostic procedures (3), and others
exposed in the course of their work (4).
Similar findings have been reported
from individuals involved in radiation
accidents (5) and in survivors: of the
atomic bombings of Hiroshima and
Nagasaki in 1945 (6-8). One of the
more interesting and possibly moresignificant points in all these studies was
the observation that chromosome aberrations can persist in circulating lymphocytes for many years after the
exposure. It seemed of interest to deter-
mine whether residual damage of this
type also occurs in Marshall Islanders
who were exposed to fallout radiation
(9).
These people were accidentally exposed to radioactive fallout on Rongelap Island in 1954: the wind shifted
unpredictably after the detonation of a
high-yield nuclear device at Bikini, 160
km away; 64 inhabitants were exposed
to 175 rads (estimated, whole-body) of
gamma rays. Eighteen other Rongelap
Islanders, away fishing on a neighboring island, were exposed to 70 rads
(estimated). Exposure resulted in tem-
chromatid aberrations. Karyotypes were
made in cases where the counts were
equivocal or where chromosomes of
questionable morphology were seen.
Only aberrations that were agreed on
porary depression of blood cells, skin
burns from beta radiation, and internal
absorption of radionuclides, the most
important being iodine and strontium.
It was estimated that the thyroid glands
of the adults received 150 rads—those
by several observers were included in -
the final tabulation. Additional karyotypes were made from eight euploid
cells, showing no gross abnormalities,
gamma rays. Recent development. of... from each of four. subjects showing
pathological changes in the thyroid is
more aberrations than most others; this
believed to have resulted from this exwas done in. an effort to detect minor
~ structural abnormalities such as small
posure (J0).
Chromosome preparations were obdeletions or inversions that could easily
Ca wae we
ge ee,
.
Woe te
tained from 51 individuals during”the
escape notice “under the microscope.
annual medical review of the Marshall
Finally, bone-marrow preparations were
of the children, as much as 1,000 rads
—from absorbed radioiodine in addition to the whole-body exposure to
Islanders in 1964; 30 of them had been-~
exposed to 175 rads; 13, to 70 rads
of gamma rays. Eight Marshall Islanders who had escaped exposure were included for comparison. The exposed
group comprised 20 males and 23 females, their ages ranging from embryo
in utero to 67 years at the time of exposure. Twenty-one were under 20 and
22 over, with males and females about
equal in number. The comparison group
included three males and five females
ranging in age from 10 to 71 years.
Unfortunately it was impossible to examine more unexposed individuals
matched to the exposed with respect to
age and sex.
Cultures of peripheral blood lymphocytes were made by use of a modification of the method of Moorhead et
al, (11); they were harvested at 48 and
‘made from’ two exposed subjects and
one control; only one preparation from
an exposed subject contained enough
suitable cells in metaphase to warrant evaluation.
Proportionally the largest numberof
- aberration-positive persons appeared in
the low-exposure group (Table 1); we
cannot explain this paradox and so
treat all the exposed subjects as one
group in comparing them with the unexposed (Table 1).
Chromosome-type aberrations were
found in 23 of the 43 exposed people
and in five of the eight unexposed. The
high incidence of acentric fragments in
the latter group was unusual and unexpected, and we cannot account for it.
The total numbers of all types of chromosome aberrations in the two groups
72 hours (/2). The slides were stained -
with aceto-orcein and examined by
phase microscopy. Because comparison
of the 48- and 72-hour cultures from
five individuals showed no differences
in aberration rates, all examinations but
one were made on SO cells of each individual from the 72-hour cultures. Al-
together 2150 cells were examined from
the 43 exposed subjects; 400 cells from
the eight unexposed.
Aberrations were scored as follows:
(i) aneuploidy, including polypioid cells,
{ii} chromosome aberrations, and (iii)
were 43 and 9—rates of 2.0 and 2.25
percent, respectively. Thus superficially
there appears to be no difference be-
tween the two groups, but we should
point out that in the exposed group
half of all chromosomeaberrations consisted of two-break aberrations such as
dicentric chromosomes, translocations,
and a ring, the remainder being acentric
fragments. In contrast, no two-break
aberrations were found in the unexposed group in which all aberrations
were acentric fragments. Only seven of
the exposed people resembled the controls in showing single-break aberra-
Table 1. Summary of cytogenetic findings in Marshall Islanders exposed to fallout radiation. Percentages appear in parentheses.
Expo-
sure
Sub-
Cells
:
jects
(rads)
soup,
(No)
175
70
scored
Cells
with
Chromosome aberrations
Sub-
(No.)
22246
(%)
affected
30
13
1500
650
10
8
12
il
43
2150
9
23
&
~
400 ., . 5.8 .
aos
oot. tbe
jects
5
F
rag:
ments
Di
icen-
trics
Rings
11 (0.73)
60.4)
10(1.53)
2(0.3)
1(0.15)
Totals for exposed subjects
21(0.93)
8(0.37)
1(0.04)
Totals for unexposed subjects
9(2.25)
AEE 8°
Abstract. Cytogenetic studies of blood
lymphocytes of Marshall Islanders, 10
|
ALSO
ao dette,
eo
Fallout Radiation
CeQag™
Total
Transl
chromo-
aberra-
ransio-
‘Total
§(0.33)
8(1.23)
22(1.46)
21(3.23)
33(2.2)
32(4.9)
§8(3.8)
35(5.3)
43(2.0)
65(3.02)
93(4.3)
9(2.25)
11(2.7)
cations
13(0.6L)
9(2.25)
some
Chroma
breaks
tions
(No.)
Tarare: NrRGRLan le, ARel
Chromosome Studies on
Marshall Islanders Exposed to
/