MARSHALLESE EXPERIENCE
241
Fig.1
Autoradiograph of tibia of pig at one month following exposure to 1 March 1954 nuclear detonation
Left: Section of bone. Right: Autoradiograph of bone.
The black areas in autoradiograph are produced by radioactivity and mark the sites of deposition of fission
products in the bone.
In addition, Cs18? , which is of minor significance as an internal radiation hazard, serves as a useful tracer for studying the movement of fallout through the terrestrial envirgnment to man, Like Sr %, Cs157 has a
gaseous precursor with a sufficiently long half-life to avoid early condensation in the fireball, Cs157 thus follows Sr® into the stratosphere and is
present in fall-out in like quantities, While there are significant dissimilarities in the ecological cycles and metabolic behaviour for the two isotopes, nevertheless there are someinteresting parallels in their behaviour
that make Cs137 useful in tracing the not-so-readily measurable Sr,
Zn® , a neutron-induced radionuclide, is easily measured and has
been followed since its identification in the Marshallese in 1957. The levels
of Zn® are also too low to be considered an internal radiation hazard.
Interest in the movement of zinc through the environment centres on the
fact that it is almost entirely transported through marine life and enters
*
é
cc
3
i
Im
CFI
man through the seafood chain. Co®, another neutron-induced radionuclide,