:
lower dose rate end in a spatial ly Jess uniform monner, though protably not te
too great an extent in smal) rodent thyrofds.
Jodine-125, has an even lowr
dose rate, and, because of its anissions of lower energy, Irratietes
non-unifonaly with higher doses to hormonogenic parts of thyrofd follicular
cells and lower doses to their mclet (Grieg et al., 1970).
Following exposure to fallout froma thermonuclear test in the Pacific in
1954, the exposed population of the Marshal! Islands exhibited a proportion of
thyroid disorders, including neoplasia, much higher than would have heen
expected.
The Marshallese, however, tn addition to 1311 nad also received
total body gawna exposure and thyroid gland exposure to short-lived radiojodines
133j.135] (Conard et at., 1980). The short-lived radiofodtnes have not been
Studied for carcinogenesis, but other effects have Indicated that their
|
effectiveness should be greater than that of I3!3, as discussed above, that
oe ay
1s, they ect more like x-{rradtat ion,
lodine-129 (Tp = 16 million years) is another fission produced radiotodine.
It appears to not have been considered an environmental or health risk
until] later fn the nuclear age, when its significance as a problen of spent
nuclear fuel processing and storage or disposal was recognized.
Its importance
in the ervirorment as 2a contaminant of food ftees was reviewed by Soldat (1976)
and Book et al. (1977).
The toxicity of '29! ts Limited, however, because of
its very long half-life (and, therefore, tow radioactivity per unit mass) and
because the thyroid can contain only a finite quantity of fodine (Ruck, 1977,
1983).