248
Ss. H. COHN
30612
1% «ite
ne fig
qu
ww 20 2
efh hg
nef
K
MALE.
FEMALE
--- §-18 yr
——~ > It yr
OF INDIVIDUALS IN GROUP
NUMBER
—-- 5-15 yr
10
16
18
ne /kg
22
26 +
10
6460
«18
22
nc / ig
ee
wo618
264
1401
22
28 +
200
«28
af ke
GAMMA ACTIVITY
ro
a
RESIDUAL
22
g/k9
—— >16 yr
O10
O14
Off
nc / kg
O22 0.26 +
OF0
O14
0.18
O22 0.26 +
ne/ko
£4
12
#20
7
+
counts /imun per kg
4
12
+
counts/min per kg
Fig.7
Frequency distribution of levels of radionuclides in various Marshallese groups in 1961
Zinc-65
zn®> was detected in high quantities ir. lagoon fish in 1954-55 [4]. The
first measurement of the body burdens of a few people from Rongelap was
made by whole-body counting in 1957 and averaged 44 nc [15]. In the 1958
medical survey, Zn® body burdens increased eightfold to 360 nc, as measur-
ed by whole-body counting in a large group of people at Rongelap (Fig. 4).
The Zn® level increased further in 1959 and then fell precipitously in 1961
to a value of 1.5 nc/kg. The decrease in Zn® level is presumably a result
of the decreased Zn® intake in the diet. If the Zn®5 level in the diet were
drastically reduced during the period 1959-1961, the observed fall in Zn®
body burden could be accounted for by the normal loss of zn® by biological
and radioactive decay. The effective half-life of Zn® in man is approximately 140 4 [16]. Although Zn® is found everywhere in the soil (10 mc/
mile?), only in the vicinity of the Hanford works is it found in people in
measurable amounts [17]. Zn®5 has also been reported in groups of reactor
4
workers [18] and cyclotron workers [19],