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165  Strontium 90 Less An Ogre Than Painted, But How Much?
     The Washington Post, August 23, 1969

     Radioactive strontium (Sr-90) ranks among the ugliest byproducts
of nuclear fission and bomb testing.  The 28 year half-life of this
major ingredient of fallout constitutes a lingering reminder of our
essays in worldwide pollution.

     Sr-90 is known to concentrate in bone, and its main hazard
is held to be the production of leukemia and other cancers by local
irradiation of bone marrow cells.  The average global burden from 
existing residues of Sr-90 has been calculated to be equivalent to a
total dose of 80 millirads of radiation in bone marrow over the
lifespan, which can be compared to 100 millirads per year from cosmic
rays and other natural sources.

     Fallout residues thus deliver only a small amount of radiation
compared to background and are unlikely to add as many as one case of
cancer per million per year to our existing miseries.  Dr. Ernest J.
Sternglass of the University of Pittsburgh has reignited public
anxiety about Sr-90 with the suggestion that 400,000 infant deaths in
the United States since 1950 are attributable to Sr-90 fallout from
bomb testing.

     The kernel of his argument is that infant death rates fell
steadily between 1935 and 1950 and should have continued to drop at
the same pace if there had been no fallout.  On this argument, our
infant mortality rate should have been reduced by now to 13 per 1000,
but the rate has gone down more slowly since 1950 and is about 22.  He
argues that the difference, or 0.9 per cent of babies born in 1968,
died as victims of fallout.  This would imply that we have
underestimated the lethality of Sr-90 by a factor of 1000.

     The country deserves better science than this.  Anyone who will
take the time to follow Sternglass's argument will see that it is
based on the unsupported assumption that mortality rates will continue
to improve at a constant pace, taking no account of either the social-
economic or the medical factors that dominate such statistics.

     Suffice it to say that most of the improvement up to 1950 can be
traced to the control of infection by antibiotics and general hygiene,
while we have been much less successful in mitigating or preventing
congenital malformations.  Furthermore, nonwhite children not only
started out behind white ones in 1950; their relative improvement
since then has been much poorer than that of the whites.

     Are we to say that black skin makes for higher sensitivity to
Sr-90?  What a convenient excuse not to do the hard work needed to
clean up our national disgrace: that a child's chance to live depends
on his race.

     Dr. Sternglass's "expose" has nevertheless called attention to a
surprising lack of experimental work directed specifically at the
genetic effects of Sr-90.  In part, this lack stems from a
preoccupation with the similarity of Sr-90 to radium and its
concentration in bone.  More important, we still have an incomplete
scientific base on which to ask the right questions about the effects
of radioisotopes on DNA and chromosomes.  We do know that these
questions are important.
  
     The one published study I could find was reported in 1963 by
the respected Stockholm geneticist K.G. Luening.  He gave huge
doses of Sr-90 to male mice, which were then mated.  Among their
offspring, the proportion of dead embryos increased to 12.3 per cent,
compared to 7.8 per cent for the controls.  But if we extrapolated
the doses back to our own load of Sr-90, the effect would be
imperceptible.

     Dr. Luening's studies do not lend themselves to exact
quantitative analysis, however, and no one has made a thorough
examination of the genetic effects of chronic exposure to moderate
doses of Sr-90.

     It is known that Sr-90 decays to an unstable isotope, yttrium-90,
which has a half-life of 64 hours and very different chemical
properties from those of Sr-90.  Since yttrium is distributed through
soft tissues, unlike strontium, it is not far-fetched to question
whether it exerts some genetic effects either by general radiation
or by more specific association with DNA.  Radioactive decay of atoms
(like phosporus 32) actually incorporated in the DNA molecule is known
to have a disproportionate effect in producing genetic damage.

     My imagination does not permit me to stretch these uncertainties
to 400,000 infant deaths.  We may be dealing with less than 1 per cent
of that burden.  But if we play with fire, we ought to maintain a
higher level of unremitting skepticism and vigilant research, or in
the end we will learn the hard way.
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