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46
|
:
10
15
LCG
mg 34168
mg CREATININE
Figure 47. Urinary BAIB excretion (mg-8-amino-iso-butyric acid per mg
creatinine) versus body load of Cs- * (uC), Rongelap inhabitants, 1959.
0.06; unexposed, 2.10 0.04). A scatter plot of
Cs*** levels and BAIB levels shows no correlation
(Figure 47), and neither does a similar plot between Zn* levels and BAIB levels. The mean
BAIB excretion level for 18 Micronesians, who
were on Utirik at the time of the atomic explosion
and therefore not exposed to significant radiation,
was 2.21 40.13, which is extremely close to the
mean value for the Rongelapese. Among the Utrik people 83% were high excretors, which is not
significantly different from the Rongelap group
percentage. A numberof complete families are in-
cluded in the Rongelap sample (i.e., father,
mother and at least one child); of these the highexcretor by high-excretor matings are the only
ones providing significant genetic information.
There were |1 such matings with a total of 31 offspring (29 high excretors and 2 low excretors). One
of the low excretor offspring wasillegitimate, as
determined by. blood group data, but the other remains as an unexplained exception to generic
hypothesis.
Rubini et al.?* have recently demonstrated thats
BAIB excretion can be a sensitive indicator of
radiation exposure. The mechanism involved ts
- probably the same as that underlying the effect of
nitrogen mustard on BAITB excretion.** Such
agents markedly increase DNA breakdown; the
thymine thus released is effectively converted to
1185593
*
BAIB in mai:****and excretediinurine, sincexQe
appreciable teBitar reabsorption ofBAIB Gc-
curs.**It ig unlikely 1that the high incidence of high’
BAIB excretors
jin Rongelap is due.to radiation. The identical "average BAIB valuesin the exposed and unexposed groups preclude the possibility that the elevation is due to the fallout exposure in 1954, and it appears that radiation exposure (at the levels received at Romgelap) has no
long-term effect on,BALB exeretion. The lackof
correlationwath tl
47 and Zn°°-body burdens
rules againstthe elevation being dueto the present
retained iiernalradiation. Thenearly identical
values in thé-Uttrtk growpwho received a yery
smaltdose of radiation, and who havemuch lower
body burdens of radionuclides, is also consistent
withthe thesis that a high incidence of thegene
undeflying B-amino-éso-butyric aciduria Is re+
sponsible for the observed BAIB excretion rai
The expression of the normal geneticdifference
probablydue-to;differential metabotistn of BAIB
by high and bow excgetors.**
The level ofBAIBexgretion among‘thear
shaltese is the | nig
-reported for any populaon, Bipod group aaa other anthrépological
data on these people suggest a Southeast Asiatic
origin; if this is true, a high BAIB level can be
predicted for the populations of that region.
Studies of some Asiatic populations have given