260
RADIOACTIVITY IN MAN
which represents a dose of about 0.35 r per year.) The influence
of this light contamination on the people's body burdens of radio-
nuclides has been measured by radiochemical urine analyses and
the very sensitive whole body gamma spectrographic techniques
using a steel] roomto Jower the backgroundradiation level. Betore
their return to the island in 1957, gamina spectrography carried
Figure 8. Steel room used for whole body gammaspectroscopy.
e
ut a”
yULZ |
Ms
outat Argonne National Laboratory on four Rongelap people (24)
showed the presence of Csand Zn™, the latter due to the eating
of fish which selectively concentrate this isotope.
Asa result of this study a stecl reom with -oin. dick walls.
weighing 21 T.. was constructed at Brookhaven National Laboratory and transported to the Marshall Islands for use in subsequent
surveys carrying out whole body gammaspectroscopy (see Figure
&). The increase in body burden of these isotopes after the aforementioned people had been living back on Rongelap one and onehalf vears can be seen in Figure 9, Cs’ values increased over one