33
Vi.
RADIOSTRONT TUM
Summary
Strontium-90 1s the important strontium fsotope in radioactive fallout.
It has a 29-year physical half-life and it and its short-lived yttrium-90
daughter anit beta particles.
Strontium behaves Vike calcium; hence, bone is
the principal site of 90Sr concentration. Unlike the other fission products
discussed herein, strontium has a long residence time and slow turnover rate
once it fs incorporated into bone mineral, characteristics that enhance its
radlobiologic significance.
| The metabolism of radfostrontium, its similarity to calcium, fts concentration in bone and transfer to milk were all documented in the early 1940s.
The effects were also implied in those papers that suggested its use in the
treatment of bone cancers.
The carcinogenic potential of radiostrontium was
documented by the late 1940s, after having been determined in animal studies.
Isotopes of strontium were known to be canponents of fallout by 1950, and
reports of fallout 90Sr appeared in the open literature tn the early 1950s.
Long-term studies on the effects of low levels of 905r began {and continue)
at several laboratories to investigate and better understand the late effects
of this radionuclide on bone and bone marrow.
Environmental Pathways
Isotopes of strontium were identified by 1950 to be potential contributors
to enmtronmental radioactive contamination fran the detonation of atomic
weapons (Glasstone et al., 1950), and subsequently 29%Sr was documented in
the open literature as a conponent of fallout (Efsenbud and Harley, 1953,
1956}.
Soon, the global nature of the fallout was discussed with regard to