234
THE SHORTER-TERM BIOLOGICAL HAZARDS OF A FALLOUT FIELD
DISCUSSION
It appears that this is a very
very strong assumptions that injury processes
plied by Col. Brennan.
Dr. Bond exhaustively demonstrated the
facets that determined depth-dose patterns in
proved wrong,it is quite evident their theories
will predict inaccurately. What appears more
importantis that as further analyses are made,
by movement, by clothing, by a foxhole. If
one were prone or supine, immobile and nude,
suspended 5 centimeters from the ground, the
effect would be great indeed at a beta-gamma
ratio of 50 to 1.
For situations that I can see with dose rates
that are probable, one would have to be precisely prone, immobile, and nude and probably
dead. Not meaning to introduce levity, but
this is a difference of opinion, and certainly
more study is needed to resolve these differ-
feasibility.
important area in which further analyses are
necessary.
phantoms.
From the data of Chamber, Imirie
and Sharp, he conclusively demonstrated that
the patterns observed in the fallout field and
with initial radiation are approximately what
theory indicates they should be when
the
source is treated as multiple separate discrete
sources, and using the appropriate buildup
versus distance considerations. The inadequacies of air dose to express biological effect
was proved, and the dependence of the
logical effect on depth-dose pattern
evident. It can only be hoped that
approaches and conclusions of Drs. Borg
biowas
the
and
Bond will be used by the hazard-evaluation
people, and by those people performing further
empirical field studies.
In addition the apparent acute hazard of
neutrons to man was dealt a rather severe
blow when depth-dose considerations were
dropped by use of what one might call the
engineering RBE from a maximum of two to a
mouse to less than 0.1 for a large animal, such
asman. This is in respect to the acute effect.*
In the section on biological repair, Dr. Hen-
are linear.
If these basic assumptions are
one realizes the death function both acutely
and chronically is exceedingly complex. Repair processes proceed at different rates in
different tissues. Death can be reached by a
multiplicity of mechanism and causes, and it
appears that much more experimentation with
all the permutations and combinations of radi-
ation techniques, of varying dose rate, area of
body irradiated, fractionation, etec., will be
necessary to finally resolve the relationship
between total dose, dose rate, fractionation
and life shortening.
The areas of agreement seem to have broadened considerably. Although Dr. Blair doubts
half times for the recovery of injury processes
can be correlated with any measureable physi-
ologic parameter, it appears that this would be
a desirable area to investigate.
From the practical standpoint, a correlation
of recovery in peripheral blood with half time
seems desirable for here is a point to use in
extrapolation to man, since long term hema-
tologic data is becoming available in the
shaw has courageously proposed a work capacity
Marshallese. It is quite evident that this is
one area in which the direct clinical research
accepted gratefully by those who haveto esti-
It was of interest that Dr. Trum’s date on
versus dose and time graph.
This will be
mate hazards. However, it can only be hoped
that they will use it in the manner that was
proposed, and with all the reservations that
Dr. Henshaw presented. I can’t help but feel
that the rather flat depth-dose effect response
that Dr. Henshaw presented for man might be
much more steep if all of the air doses that
went into it were appropriately converted to
tissue dose.
Dr. Storer, Sacher, Blair and Jones were
fortunately assembled all in the same room at
the same time. The result was certainly from
my standpoint most educational and interesting. As a basis for all approaches are some
“Subsequent work has shownthattherelative effectiveness factor may
Ue in the vicinity of 0.5.
is not acceptable.
the hematologic recovery in burros looked very
muchlike the Marshallese data to date.
In the section on beta burns, Col. Brennan,
making certain assumptions on energy and
uniform distribution of fission products, calculated the contributions of dose at a point in
a planarfield as a function of radius and height
above surface. This approach coupled with
the Spencer-Fano equation could describe the
dose at this point from polyenergetic fission
field more adequately. This dose should repre-
sent the maximum hazard sincedrift, directionality and shielding wouldall effectively diminish
the effect as previously considered by Drs.
Bond and Borg. I personally do not share the
feeling that beta bath is a real hazard as im-
The contact beta burn
is areality. The beta bath effect is diminished
ences.
In respect to the biological effect of beta
irradiation, the obvious question is, do animal
studies apply to man? In part, I think the
answer is yes. However, J have been assured
by manyveterinarians that the skin of cattle
and of swine is particularly more reactive and
prone to produce hyperkeratosis and acan-
thotic lesions as observed.
There can be no
question about a qualitative similarity, but I
somewhat question whether one can say there
will be quantitative similarity between the
animal studies and man. I personally think
that the cosmetic future of the Marshallese
is rather good. Certainly Dr. Conard in his
continuing studies of the Marshallese through-
out their lifetime or his will find out the answers.
Particular importance in assessing the beta
hazard, I believe, are the attentuation curves
that Dr. Conard presented.
In Dr. Morgan’s presentation it was certainly
welcome news to know that the National
Bureau of Standards Handbook 52 will be
revised and have a broader base and include
new nuclides and both single and chronic hazard
estimates. I do not see how he and his group
can possibly do all this work that is involved in
these revisions and we certainly owe themall a
debtof gratitude.
Dr. Jones’ studies on iodine-13! uptake in
the thyroids of cattle and of man certainly
were most encouraging and show quite con-
clusively that the dose is small. The observations of Trum concurred with this indeed.
OF TOPIC Vv
235
I was most interested in the studies of Dr.
Durbin on the kinetics of strontium-90 uptake,
retention and excretion. It goes without saying
that much more studies of this type, as has
been so ably demonstrated by Dr. Langham
a few moments ago, are urgently needed in a
wide spectrum of animals and over the wide
entire spectrum of the radio nuclides.
Dr. Placak’s observation on plutonium-239
and its distribution in the Nevada test site
and areas remote from there quite conclusively
demonstrated that though there is apparently
no hazard here again is another subject that
must be closely watched and a continuing
study is essential.
Dr. Stannard listed the physical and physiological parameters necessary to evaluate the
pulmonary hazard from particle inhalation.
However, the problem was not putto rest. It
looks as thougha start has only been made, and
a tremendous amount of work yet is to be done
to try to evaluate a single nuclide, let alone
the sphere of size and substances from fission
products.
In Major Woodward’s absence, Dr. Schrodt
presented the problems that were closcly allied
to the previous observations of Dr. Jones and
Col. Trum onurinary excretion of iodine-131.
It seems that there is one minor or possibly
importantdifference here. It seems inconceivable that man could be taking the iodine in
other than by inhalation. The cattle intake
was from feed, predominantlygrass.
The studies of Dr. Lindberg and Dr. Larson
brought out what struck me as two rather im-
portant considerations.
First, the fractiona-
tion of fission products by the size of the particles between plants on which animals graze,
and the underlying ground, and the fractionation of iodine-131 and strontium-90 with dis-
tance from the site of detonation. It appears
that all of these factors must have to be fed
into the ultimate models for assessing both
acute and long term fallout hazards.
I was quite impressed with the mass of data
that Drs. Weiss and Cohn presented. However, as a physician, I find myself completely
unable to interpret the importance. Tt appears