UNITED NATIONSREPORT OF THE
UNITED NATIONSSCIENTIFIC COI\IMITTEE
ON THE
EFFECTS OF ATOMIC RADIATIONNOTE
Throughout this report and its annexes cross-references are denoted by a letter
followed by a number: the Jetter refers to the relevant technical annex (see Tableof Contents) and the number is that of the relevant paragraph. \Vithin each technicalannex, references are made to its individual scientific bibliography by a number
without any preceding letter.
Symbols of United Nations documents are composed of capital letters combined with figures. Mention of such a symbol indicates a reference to a United
Nations document.

ANNEXES

Annex D

ENVIRONMENTAL CONTAMINATIONTABLEOF CONTENTS

Paragraph

I. ~ I O A C T I V EFALL-OUT ....................................

1
Fall-out mechanisms ..................................... 6
Measurement of fall-out ................................. 9
Airborne activity ..................................... 10
Fall-out deposit ....................................... 12

I1. COMPUTATION
OF EXTERXAL DOSE FROM FALL-OUT
DEPOSIT ...... 20
I11. SrDO
AS A N INTERNAL SOURCE ............................... 36
Evaluation of SPOas an internal hazard .................... 28
S P Oin soil ............................................. 29
SrDO
in food-chains ...................................... 33
Discrimination factors .................................. 34
The soil-vegetation step in food-chains ...................... 37
Concentration of SrsOin foodstuffs ........................ 48
Calcium sources in diet .................................. 50
Stable strontium sources in diet ........................... 52
Daily intake of S P Oin man ............................... 53
SrPOin human bone ...................................... 55
The importance of the stable strontium determination ....... 56
SrsOdistribution in different bones of the skeleton .......... 57
Uniformity of SroOdistribution in bone ................... 58
The problem of computing skeleton dose from SPO......... 63
Concentrations of S P Oin man ........................... 66.

I V Csla7AS AN INTERNAL SOURCE ............................... 68
bllethods for measureme~tof concentrations of CslJ7 ......... 71
Concentrations of CslB7ill foodstuffs ....................... 73
Daily intake ofin man .............................. 74
Concentrations of CslS7in man ............................ 75
Dose rate from C 3 in a n ......................... 76.

V DOSESFROM TROPOSPHERIC FALL-OUT ........................ 77
External sources ........................................ 78
Internal sources ......................................... 79
S e e and Ba140 as internal sources ....................... 80
1131as an internal source ............................... 84................ 91\TI ESTIMATION
OF DOSES FROM FUTURE FALL-OUT
Estimation of fall-out rate and deposit in the future ......... 94
Case 1 : Tests stop at the end of 1958 .................... 102
Case 2 : Tests continue ................................ 103
Values of F, (0) and F d (0) ............................ 107
Methods for dose estimations ............................. 111
External irradiation of gonads caused by CslS7............. 113
Internal irradiation of gonads caused by.............. 114
Total irradiation of gonads cause by Csla7 ................. 115
Internal irradiation of bone marrow caused by SrsO........ 116
Estimated doses ........................................ 124
T'II . CALCULATION
OF BIOLOGICAL EFFECTS ........................ 127
Leukemia. assuming a linear dose response relationship andno threshold ........................................... 128
Leukemia. assuming a threshold of 400 rem ................. 129
Major genetic defects ................................... 130
VIII XOTEo x I K F O R ~ A T I O S D O C U ~ I E N T.......................... 131
REFERE:;CES
TABLES.

.

98

I. ~ I O A C T ~ TFALL-OUT,
1. I n a nuclear explosion, several hundred radioactive
tsotopes are produced from fission. With exception of asmall number of isotopes they have short half-lives anddecay rapidly. In addition to fission products and residual fissionable material? a number of neutron-induced
radioisotopes are produced. Their nature depend on thesurrounding materials. Also, most of the radioisotopes
formed by neutron-induction have short half-lives,
usually less than a few hours.

2. The radioisotopes formed in a nuclear explosion
are distributed by rneteorologicai processes and eventually reach the surface of h e earth. They enter thehuman body in el-era1 ways : first, by direct inhalationof airborne material ; second, through uptake and deposition on vegetation eaten by humans; third, by transfer
through animals and, fourth, by contamination of water
3. I n addition to considering the esposure from material taken into the body, it is necessary to consider external radiation exposure. Except at the immediate siteof the explosion, external radiation from airborne material is negligible in comparison with the external radiation from fission products deposited on the ground. The
external radiation from deposited fission products depends mainly on their activity, half-lives and gamma
emission characteristics.

4, Materials entering the human body deliver a dose
which is closely related to the time they are retained by
the body. This means that many of the isotopes producedin fission do not present radiabon hazards since they do
not enter significantly into metabolic processes. Attention has therefore been centred on isotopes which arepotentially hazardous by reason of: (1) high fission
yield, (2) fairly long physical half-life, (3) high absorption by the body and (4) long biological retention time.
Special consideration is given to elements that concentrate in specific tissues, even though they do not have all
the characteristics described. Using these criteria, themost important isotopes would be expected to be SrWand CsZ3;.

5. I n addition to the fission products and certain
neutron-induced activities, some of the residual fissionable material, such as isotopes of uranium and plutonium, will also be distributed by meteorological processes and can be hazardous since they are alpha emittingbone seekers. However. the absorption by the body isvery low and at present there is no evidence of any
uptake o i these materials in human tissues.

7. The heat of the fireball from explosions in the
kiloton* range is dissipated quite rapidly and the fission
products do not normally rise above the tropopause. The
radioactive cloud from an explosion may travel manytimes around the earth and. during this time, the tropospheric fall-out is deposited at latitudes fairlp close tothat of the =plosion. The relative magnitude o i the contribution of the stratospheric and tropospheric components to the deposit therefore is different for difierent
localities. Half the radioactive material in the tropos,here is removed by deposition, mainly through rainfall, in about three weeks' and the deposition is effectively complete within three months. This deposit consists mainly of isotopes of fairly short half-life. A t thepresent time the tropospheric fall-out is deposited intermittently during the year and a certain deposit of shortlived activities is built up and maintained. Isotopes of
special concern for this report are Srso, ZP5, Ru103,
RulOa, Ba140and Ce144.
8. If the fireball touches or comes dose to the groundin a nuclear explosion, there will be a local fall-out that
constitutes a significant fraction of the total activity
produced. This type of fall-out consists of radioactivity
erried down by relatively large particles and in addition
to fission products, contains shortlived isotopes producedby neutron induction in the material from the grounddrawn into the fireball. This annex is concerned mainlywith stratospheric and tropospheric fall-out.
Mcaslcreritent of fall-out
9. Measurements have been undertaken to determine
ccncentrations of radioactivity due to fall-out in air, soil
and biological material, especially foodstuffs and humanbone. Emphasis has been placed on a determination of
the world-wide distribution of SPO.A survey of methods
which have been found to be valuable in relation to thework of this Committee is given in annex E, and all
relevant data from fall-out measurements that are submitted to this Committee are collected in tables X I V to
XX and in the map at the end of the volume.

Airborjre activity
10. Air samples can be obtained by filtration of air orby electrostatic precipitation. Studies of vertical distribution of fission products in the atmosphere have been
made using filters carried by aircrafts or balloons. The
samples are cou~ltedfor total beta activity after decay ofnatural radioactivity o r analysed for individual nuclides
after radiochemical separation. One cause of uncertainty
in the measurement of airborne activity at high altitude
is in many cases the insufficient knowledge of the-.collec..
tion efficiency for this particulate activity.

-_-

6. The fireball from a nuclear explosion in the megaton* range cools so slowly that a major part of the fission
products enter the stratosphere, where they become
widely distributed. From this reservoir, the fission products fall onto the earth's surface over a period of many
years (stratospheric fall-out) . These fission products
therefore consist mainly oi long-lived isotopes. The
mechanism of transfer from the stratosphere to thetroposphere is not completely understood.
NOTE:Throughout this report and its annexes cross-reier-.

ences a r e denoted by a letter followed by a number : the letterrefers to the relevant technical annex (see Table of Contents)
and the number is that of the relevant paragraph. Within eachtechnical annex, references are made to its individual scientificbibliography by a number without any preceding letter.

11. hleasurements at ground level in 1956-1957 show
a concentration of S P Ofrom 10-l9 to lV17 c/l of airZJ.
For altitudes up to about 10,000 metres, the amount ?ffission products per kg of air increases slowly with a h tude, but the rate of increase is much greater above thet r ~ p o p a u s e ? . At
~ ~ ~the. present time there are too few
data available to permit a complete inventory of tile
stratospheric content.
a* I n a nuclear explosion the total energy release is compared''with the energy release by T N T (trinitro!oluene)
hen it3
cuplodes. Thus a 1 kiloton nuclear explosion 1s one ~vhlchPtoduces the same energy as the explosion of 1 kiloton (10' tor?s)of TNT, namely of about 10" calories. A 1 megaton e ~ p l o s t msimilarly would correspond to the explosion of 1 megaton
I(10' tons) of TNT.

Fall-out deposit
12. Fall-out deposit measurements are necessary toestimate the external irradiation of man and the amountof specific isotopes likely to enter the biological foodchains and so eventually the body.
13. Many countries are measuring fall-out rate andaccumulated deposit. At present, there are available tothis Committee results from about 350 stations. However, large areas of the earth are not covered by thesurvey and not all the stations and laboratories operate at
the same technical level. The results received by theCommittee, however, allow a number of useful calculations to be made.
14. Soil analysisD?B and various types of collectors,
are used for studying fall-out deposit. Table I gives
some technical information on these collectors. The
agreement between results obtained by different methodsof collection is reasonably good.
15. The location of sampling stations is of the utmost
importance in obtaining representative samples. The location of new stations should be determined in consultation with meteo<ologists to assure a representative collection of prec~pitation (especially in areas wheresnow-fall is important).
16. With daily collection on gummed film or gauze,
the amount of long-lived nuclides in the samples is generally very low ;and, owing to the large soluble iraction,
the washing effect of rainfall is considerable. For thesereasons the radiochemical determination of SreOin thesesamples is talueless. The S P Ocontent can, however, becomputed by measuring the total beta activity of thesamples and following its decay (assuming that all theactivity originated in a single test).8 However, in thepresent situation. with stratospheric mixture of materials from different tests, this computational method isunreliable unless it is repeatedly calibrated against radiochemical determinations on samples collected by the pot
m e t h ~ d . ~A* lmore~ refined method for the con~putation,
taking into account the stratospheric reservoir, has recently been worked out, but this method is based on datathat are not generally available.1° The advantages of thegauze or gummed film is that they allow a daily surveyof fall-out at many different stations.
17. Results reported to the Committee up to March
1958 are shown in tables XIV, X V and XVII and in

Evaporalia sarn$lirrg
worn pol cdkcfion)

Lfcfhod

Collection.. .............. Rain water and dust
Area, approx. range in m'.. 0.05 to 17
T i e of collection..
1 to 30 days or during
precipitation, also 3months' samples
Sample preparation andevaluation.. ........... The water is evaporated and the residue
mounted for counting or first ashed orradio-chemically analysed.

.......

Efficiency of collectionin per cent.. ...........

100'

Assumed 100 per cent effective.
Determined by measurement of effluent water.
The pot collection method is used as reference.

the map at the end of the volunle where the fall-out
deposit at 1 July 1957 is plotted.
18. The world-wide fall-out rate and deposit of SrQO
is uneven and there are variations with latitude whichshow maxima in the region between 30° and 50' Northand South, with a minimum near equator, as shown by
the curve on figure 1. This curve, showing the fall-out
rate during 1956 and 1957, is based on data obtained byradiochemical analysis. Data from soil analysis" andfrom gummed film measurementsx0 give the same overall picture ior fall-out deposit, although the peak in thenorthern hemisphere seems to be somewhat broader. The
computation of a world-wide average of fall-out rate anddeposit is rendered difficult by the existence of large
It is dear, however,areas not covered by surveys.D103-10athat the southern hemisphere has accumulated deposits
that are lower than the average, while areas in thenorthern hemisphere (Japan, the United Kingdom, theUnited States) have deposits of about three times theworld average.lO-l5It should further be pointed out thatthe large deviations from the average are towards thelow side.
19. It has been reported that the fall-out rate in somecountries shows seasonal variations,I3 apparently correlated with the known ozone fluctuations. This is, however, not supported by data from other countries.
11. COMPUTATION
OF EXTERNAL DOSE

OM

FALL-OUT DEPOSIT

20. The fall-out deposit contains gamma-emitters andis therefore an external source of radiation. The composition of the fission products and the corresponding
gamma intensities change with time after an explosion.
In the tropospheric component there is a large numberof short-lived gamma-emitting isotopes and in the stratospheric component Cs13' is predominant.
21. It is impossible to make direct measurement of thevery low exposure rate from fall-out except at areas
close to test sites. Therefore, more indirect methods must
be used.
22. T o compute the exposure rate from deposited
fission products, it is customary to assume that they are
uniformly distributed over an infinite plane. The exposure rate from primary radiation is approximately
Independent of the distance above the ground, provided

Fi:trafion and ion crckangc

Rain water and dust
0.07 to 3.1
4 to 30 days or during precipitation

The water is passed throughpaper, pulp, paper filter,
anion exchanger and cationexchanger. The paper
and the exchangers are
separately ashed andm o ~ n t e dfor counting.

GvrnmrdBm

Dust
0.1
1 day

The gummed film isashed and the residue mounted onplanchet or sealed
between plastic
films for counting.

Gaurr

Dust
0.3
1 &Y

The gauze isashed and
subsequently
treated as thegummed film.

NorthLatitudeSouth

Figtire I. Veteorological factors for the different places of observation have not been taken into account

this does not exceed a few metres. One gets the eupression :1 = c X Ey X FdT(t)
(1)
where
I is the exposure rate (mrad/year)
mrad.Am2c = 0.1
year.mcMev
Ey is the average gamma energy emitted per disintegration ( Mev)
FdT(t) is the total activity of the deposit (mc/km2)
This formula can be used for individual y--emitterssuch as CslS7, or for mixtures if E7 and FdT(t) are
known.
23. Two computation methods for the exposure ratefrom composite fall-out deposits have been used. One
computation is based on measurements of total betaactivity of daily gummed film or rainwater samples.16
This method has been shown to be reasonable at present
even though the radioactive fall-out now is a misturefrom several explosions.'0

24. The other method talces into account that the exposure is derived from two components: (1) a "fresh"
component of tropospheric origin and (2) a "long-lived"
component (CslS7)mainly of stratospheric origin.17 It isshown that the 30-year dose** can be expressed withreasonable accuracy as :D30 = aAt
b-40135(2)
where a and b are constants, A, is the total beta activity(mc/km2) and A',,,,
is the activity of Cs13; (mc/km").
The values of the constants depend on the collection time
and the time before the beta counting is done.
25. Values obtained for the infinite plane 30-year
exposure due to fall-out deposited up to the end of 1957
are shown in table XIV and are of the order of 10 to
180 mr. The dose delivered to the gonad and bone marrow must be computed taking into account shielding,weathering and leaching factors. The shielding factor
accounts for the reduced dose rate during the time thepopulation spend indoors where the dose rate from fallput deposit is reduced. whereas the weathering and leachlng factors account for movement of the depos~ted
gamma-emitting isotopes from the upper layers oi theearth's surface, for esanlple to lower layers of the soil.
Taking all these effects into account, composite reduction
factors ranging from 3 to 21 have been used in reports
received by the C ~ m m i t t e e . ~Using~ ~ ~ an. ~average~ . ~ ~ reduction factor of 10, the 30-year genetically s i ~ i f i c a n t** The 30-year dose, which is approsirnately .+e geneticallysigcificant dose, is the dose received by an in&vldual for the
first 30 years of his life.

+dose would be about 1 to 18 mrem. It should be emphasized that this is only the dose from what is alreadydeposited. and that the total dose from what has been
injected into the atmosphere \\;ill be higher, as discussed
in paragraphs 94 to 115. Including the tropospheric component, the total dose from the external component ill
be of the same order of magnitude as the dose from fallout isotopes taken up by the body.
111. SroOAS AN IXTERXAL RADIATION SOURCE
26. Among the f d - o u t isotopes, SrnOis of particclarinterest on account of the biological hazard that thisisotope presents. Strontium is an element of the alkalineearth group, and its chemical properties are m many
ways similar to those of calcium. barium and radium.
Thus SrgOco-precipitates with calcium as phosphate or
carbonate, and is included in the bone structure. Once
included, SrnOmay remain in the bone structure formany years. the exact time not being knotvn.ls The
osteocyte and bone marrow cells will be irradiated by rhe,8 particles from SrSnand its daughter product Yon.The
ultimate question to be answered is the size o i bone andbone marrow doses delivered by these isotopes.
27. To evaluate the present hazard from SrgOthe concentration in the bone must be deternlined. For hazard in
the future, however, the change in this concentration,
together with the concentration of SroOin different f o ~ d stuffs, should be determined. Of course, SroOprimarily
follows stable strontium through the food-chain, i.e.,
irom the deposit on the ground, through uptake by plants
and transfer through animals. For practical reasons,however. it is the calcium contributors to the national
diet that are mostly studied.

Evaluation of SPOas apt interjral hazard
28. A Sr" programme should attempt to take up thefollowing problems :( a ) Amount of SPOso far deposited ;( b ) Amount of SrgOto be deposited :(c) Rate of deposition of SroO:(d) -4s a result of (a), ( b ) and ( c ) :Eventual total accumulation of SroOon the ground :(e) Kinetics of strontium in the biological cycle :( f ) Present bone level of SreO;(g) Future bone level of SrsO.
TOthis end, the determination of SroOin the follo~vingmaterials is needed :(a) Human bone:(27) Components of the human f ood-chains ;(c) Fall-out materials (collected by the pot method) ;(d) Air (atmosphere and stratosphere) :(e) Soils, grazing grounds and waters.
The determinations oi stable calcium and strontium inthe above-mentioned materials are of importance since
their concentration is of value in interpreting the SrcO
results.

Country .........................
Period of measurement.. .......:..
SrgOin mc/km2. ..................
- -Japan28January-May 1957
2.5-6.3

SPOitt soil
29. Soil analysis is useful for the determination of
accumulated SreO,as soil can be considered as a primarycollector. For determination of fall-out rate, however,this method is not sufficiently accurate. In addition, thesoil anal 4 s has little value for the direct estimation ofpresent .$roo hazard owing to the difficulty of estimating
the relative importance of the uptake of S P Oin plantsfrom soil and from foliage retention, that is, fromuptake of SreOdeposited directly on the leaves.
30. The extraction of Sr" from the soil for analysis
is difficult and many techniques are used, such as alkaline
fusion. acid leaching, ammonium acetate leaching andelectrodioipsis. The large amount of soil needed foranalysis makes the alkaline fusion impracticable and theacid leaching method is very much preferred.E13

31. The upper 5 an of the soil retain at present about
70-80 per cent o i the deposited SrnO,the exact d u evarying somewhat with the type of soi1.12J0-23The total
amount of SrnO,as determined in different countries. isgiven in table 11. Wlere only the upper 5 un of the soil\$-as analysed, a factor of 1/0.7 has been used to calculate
the total amount. The numbers given are the averageand the range of reported values. The values are in
reasonable agreement with values for total deposit of
SrnOobtained by other methods of m e a s ~ r e m e n t . ~ * " J ~ ~ ' ~32. For the study of the behaviour of Sr90 in foodchains, it is useful to express the SreOconcentration in
activity per gram of available calcium.** The amountof calcium per kg of soil is extremely variable : for example, different areas in the United Kingdom show arange from 0.1 to 150 g calciumhg soil,*? although asmall part only of the calcium is likely to be labile andavailable to plants in soils with the higher concentrations.
Also, the available fraction of calcium is very variable :for example, in two different localities in the UnitedStates 3 and 42 per cent respectively of the calcium isa ~ a i l a b l eThe
. ~ ~ availability to plants may also vary if its
chemical form in the soil changes with time or under
different conditions. Similarly the chemical form of
stable strontium will influence its availability to plants.
St-goill food-chains

33. From the environment to the human skeleton,
strontium follows a long path accompanying calcium.
The problems to be considered are the transfer of SrnO
and stable strontium in food-chains 2nd the transferfrom soil to plant.

Discrintirurtion factors
34. The chemical similarities between strontium andcalcium make the use of Sroo/calcium ratio convenient
for following SroO irom the environment to ltuman** For concentrations of Sr" the unit 1 micro-microcnrie( ~ p c )SrgOper gram calcium is used (1 strontium unit, 1 S.U.).

Stvedeng
Mid-1956
1.2%(0.6-2.0)

U E ; ~m.

US-ATO. M

July i957

October 1957
9.7
(3.2-13)

5.3(3.5-14.5)

USSR5
February-July 1957
6.0
(3.0-12)--&Thesepreliminary data are probably too lo\\-, as an ammonium acetzte leaching rnethod was used for the extraction of Sr'"
irom soil.

I

!
1
1

I

Alan. .........

Double tracer witheach meal

4 patients, 9 to 73

Diet + bone

0.54 (0.50-0.62)

29

Man. ......... Korrral mised

Stable Sr/Ca ratio
in diet and bone

Average adult dietin U.K.

Diec + bone

0.25

30

&Ian. ......... Kormal mised

Stable Sr/Ca ratio
in diet and bone

Average diet in
CanadaDiet -+ bone

0.5

Man. ......... Kormal mixed

Stable Sr/Ca ratios

1 normalDiet + bone

0.21

31

Man.. ........

Non-milk

Double traccr witheach meal

4 patients

Diet + bone0.44 (0.374.51)

29

Man.. ........ Non-milk

Double tracer,
single dose

2 pztients

Diet -, bone

0.35 (0.25,0.45)

32

M a n . ......... Normal mixed

S F / & ratio in dietand boneIndirect calculation

Diet + bone

0.25

33

Man. .........

Stable Sr/Ca ratio
in diet and bone(disregarding
marine contribution to diet)

Average Japanesediet and averagebone concentration

Diet + bone

0.17

34

Sheep. ........ Grass from uncultivated pasture

Stable Sr/Ca ratio
in grass and bone

6 animals

Diet --t bone

0.24 (0.15-0.31)

22

Sheep. ........ Grass from uncultivated pasture

SrgQ/Ca r a t i o in
grass and bone

6 animals

Diet + bone

0.23 (0.09-0.42)

22

Goat.. ........ Kon-milk

Double tracer, daily
dose

2 animals

Diet + bone

0.23

35

Rat. .........-

Double t r a c e r indietary

Diet + bone

0 . 5 7 f 0.02

28

R a t . . ......... Son-milk

Double t r a c e r indietary

Diet -t bone

0.2i+0.01

28

Rat. ..........

Non-milk

Lifetime feeding ofradiostrontium/
Ca

Diet + bone

0.28

27

Rat. .......... Non-milk

Stable Sr/Ca ratios

Diet + bone

0.27

27

Mouse.. .......

Non-milk

Stable Sr/Ca ratios

Diet -r bone

0.35

27

Guinea pig.. ... Non-milk

Stable Sr/Ca ratios

Diet + bone

0.22

27

Jack rabbit.. ... Xatural (on desert)

Stable Sr/Ca ratios

Diet -t bone

0.20

27

Cottontail rabbit Natural (on desert)
Kangaroo rat.. . Natural (on desert)
Con.. .........

Stable Sr/Ca ratios
Stable Sr/Ca ratios
Radiostrontium andradioiaicium a tdifferent times
SreQ asssy of Wisconsin milkshed,
1953
SPO assay of Wisconsin milkshed,
1955

Diet + bone
Diet + bone
Diet + milk

SrO'J assay in U.K.,
1955
Double tracer, daily
dose 2 animals 13
days
Double t r a c e r indietary
Double t r a c e r indietary

Diet + milk

Cow. .........
Cow. ..........
Cow. ..........
Goat. .........
Rat. ..........
Rabbit. .......

years old

Diet + milk

Diet + milk

Diet --+ milk

Plasma + foetus
Plasma -t foetus" -uthou h some of the following discrimination factors are

determined as DF (diet-blmd), they have been ~ r i t t e n

103

is very nearDF (diet --, bone), as DF (blood + bone)unity.,s. s,SU:b The range or mean f standard error is given where avai4b1e.

bones. However, the chemical behaviours of strontium
and calcium are not identical and, therefore, their utilization varies in biological processes such as assimilationand milk secretion. For example, cows utilize calciuiii
more efficientlythan strontium in producing milk. To express quantitatively the preferential utilization of one ofthese elements in a given process, the following nomenclature is proposed :Discrimination factor' D F (prmurmr+smple) =Sr/Ca ratio in sample
S r / 6 ratio in precursor
This discrimination between strontium and calcium iscaused by several physiological factors among which themost important are: referential absorption of calcium
from the gastrointestinal tract; preferential urinary excretion of strontium; preferential secretion of calcium
from blood into milk and preferential transfer of calcium across the placental barrier. The quantitative evaluation of the contributions of these physiologicalprocesses has been made under certain conditions.'*
I t is possible to define an over-all discrimination factor
for a given food-chain as the product of the discrimination factors for each step of the chain. under the condition that there is no additional entrance of strontium or
calcium from other sourres into any of the intermediate
steps. For example, in the chain: soil + grass + cow's
milk + human bone, the over-all discrimination factoris :DF (soil+bone) = D F (soil+grass) X D F (grass+aw's milk)
X D F (COW'S milkjhuman bone).
35. Various methods have been described for measuring- the discrimination factors :(a) By measuring the stable strontium/calcium ratio
in precursor and in sample ;25(b) By measuring the radiostrontium/calcium ratio,
for e-xarnple Srg0/calcium in precursor and in sample inequilibrium, either under field condition^^^*^^ or in dietary experiments :?'(c) By double tracer esperiments, for example, using
Ca4"nd Sra5.28

36. I n the case of SrOOtransfer from fall-out deposit
to human bone, the problem is complicated a t present by
the possibility that.the human bone may often not be in
equilibrium with the environment. The discrimination
factors obtained by technique ( a , ) give inherently theequilibrium value and this technique is therefore very
important for the evaluation of future risk. For thisreason, the determination of stable strontium and calcium in the steps of the food-chains is fundamental.
I t is important, however, that the subjects have lived ona diet with a constant stable strontium/calcium ratio andthat the entire diet is analysed. Some values for discrimination factors are summarized in table I11 and in paragraph 47.
Tlte soil-vegetation step in food-cha.i)ts

37. I t is very diliicult to compute an over-all discrimination factor for the soil-vegetation step. The plants
receive S P from soil through the roots and also directlyfrom iall-out deposited on the leaves and the concentration may not be uniform throughout the plant.19*20With
information available at present it is difficult to estimate
f A system of nomenclature has been earlier proposed" : inthis system the term "Observed Ratio" ( O R ) was proposed forthe over-all discriminztion between a precursor and sample andthe term "Discrimination Factor" was used to denote the discrimination that is produced by a given physiological process.

the relative importance of the two routes of entry as:( a ) The accumulated deposit is at present increasing,whereas the fall-out rate has been zpproximately constant for the last four years.D10'(b) The mechanism of deposition (dry fall-out, continuous slow precipitation, heavy showers) may change
the efiiciency of foliar retention.
(c) The type and condition of the foliage may change
the efficiency for retention of direct deposit.
(d) There are great differences in the growing
periods and, therefore, in the exposure time of different
plants.
(e) The accumulation of fission products at the stemsof plants may irlfluence the relative significance of thetwo factors, as this accumulation will depend on the fallout rate for some previous years.D4i( f ) There are indications that in soils with low available calcium contents, the root uptake of S F 0 is more
important than in soils with more available calcium.DH( g ) The depth of the root penetration, the soil type,the water supply and the depth oi ploughing may change
the root uptake.
38. For the indirect evaluation of the relative importance of the hvo components, both stable strontium andcalcium data are useful. A possible approach is based on
the measurement of the specific activity of SPOin plantand in soil (ppc SPo/g stable strontium). As the S P O
retained by the foliage- is carrier-free the ratio:
specific activity of SrsOin soil
specific activity of S P Oin plant
gives the fraction of the total SI- in the plant that comesfrom soil. If the specific activity of the soil is computedfrom the total strontium content and not from theamount of strontium available to the plant, this fraction
will represent a lower limit, and the available strontium
may in certain circumstances represent a small proportion only of the total strontium.
39. An experiment has been reported on the direct
determination of the surface contamination of grain of
the 1956 harvest in the Soviet Union. The grain waswashed with 0.5 per cent hydrochloric acid and water.
which removed at least 50 per cent of the total Srm."

40. Another approach to the problem depends on a
direct correlation of the rate of deposition of SrgO,theaccumulated deposit and the SroOcontent in any particular food. This has been attempted for milk's in the following way, taking yearly averages to avoid seasonal
effects, and assuming that the S P in milk comes fromthe following sources :(a) Uptake by vegetation through the roots, assumed
to be proportional to the accumulated deposit in soil (Fd,in mc/kmg, the value at the beginning of the one-year
period) :( b ) Direct deposits on leaves, assumed to be proportional to the fall-out deposit in a one-year period (fd, in
mc/km9).
The average S t 9 0 level in milk in a one-year period Csf
is then given by:(3)
Chl = a,l(Fd
1/2fd) b d dwhere ah, and bhl are proportionality constants.

++

41. Using data from Perry, N. Y., U.S.A., a set GI
constants ax and bhl can be computed. The values for
Fd and Jd are estimated from New York City pot data
corrected by a factor derived from gummed film datafrom places near Perry and in New York City.

Pi. Y., U. S. A.
TABLE
IV. Sr90 DATA FROM PERRY,

status of the soil as well as upon the type o i plant, conditions of culture and the rate and quantity of SrsOfallSrlC in
Periodmi,r,s.o.
sf;dd$~:;$
out. It should be emphasized, however, that the SrS0
uptake of plants from soil is effected not only by the
April 1954-3Iarch 1955 1.20
0.89
2.30
absolute quantity of calcium present. but also by the
2.78
Jan. 1955-Dec. 1955. . 1.89
2.16
degree of saturation of the colloidal complex o i the soil
Oct. 1955-Sept. 1956.. 2.86
4.57
3.36
July1956-June1957..
3.91
7.48
3.58
by calcium and other cations. such as magnesium, potassium and sodium. and this varies materially from one
From these data one calculates the constants: a\r = 0.34 S.U.
soil to a n ~ t h e r . ' ~km2/mc and b~ = 0.23 S.U. km2/mc.*
45. In the important case of rice, the outer layers of
the grain become contaminated by carrier-free Sr90
42. I n the milk from the four one-year periods, thedeposited on them from fall-out occurring during a very
derived from foliar retention are 43,
fractions of SrQO
35, 27 and 21 per cent respectively of the total SrgO short period before the harvest. The kernel of the grain
has an S P Ouptake which appears to be more dependent
content. These fractions need not necessarily be measupon accumulated deposit than upon rate of fall-out ;?aures of the foliar retention of the plants, as the relative
this will be accentuated by the shortness of the growing
contribution may have been altered by factors such as
period, by the ploughing of each season's straw into thewashing of the grass by rain, and differences in chemical
upper soil layers and also by the formation of a root mat
form of the Sfl0 that the plants had obtained from theunder certain conditions of growth. The SrgOcontent of
two origins. I t is likely also that values of a, .may vary
white rice is thus mainly dependent on root uptake,with time if the chemical state of radiostrontlum in thewhereas that of brown rice, from which the outer layers
soil changes progressively.
have not been removed, is at present more dependent on
43. T o determine the root uptake directly, crop essurface contamination.
periments have been performed in the United Kingdom
46. To distinguish between the amount of S P Oreachwith Spa tracerag6With the conditions of soil and cultiing plants through their roots, as compared with thatvation in that country, concentration of 1.1 S.U. in grasscoming from foliar absorption or uptak'e from the stem
was found for an accumulated level of 1mc/krn2 frombase, is important for predicting their relative sign&root uptake alone."&This corresponds to a milk concencance under future conditions. If, in the future, the accutration of about 0.15 S.U.? derived by using the appromulated deposit of SraOin the soil has increased conpriate discrimination factor from table III.D3GThesiderably relative to the fall-out rate. the relative uptake
constant ah* in equation (3) should thus have a valueof SrsOfrom the soil is likely to become much greaterof about 0.15 S.U. km2/mc for the United Kingdom
th,m that by other routes, especially for soil of very low
as derived from experiments lasting for one year withcalcium content. Forecasts of plant contamination under
S P s well equilibrated with soil. Experiments also indisuch future conditions can, therefore, only be based adecate a Ioliar retention ranging up to 90 per cent of thequately upon that component of present uptake which
total herbage contamination.
depends on the accumulated deposit of SrgO.
44. For other food materials and crops. a method
47. From the preceding paragraphs it may be deduced
similar to that given in paragraph 40 is applicable withthat an evaluation of a generally valid discrimination
three provisions :factor that includes the step from soil is very difficult at( a ) The relevant period during which the fall-out isbest. For defined conditions, however, some values haveaveraged should in some cases be limited to the growing
been reported. Thus DF <soil+diet) has been estimatedperiod of the plant if this is much shorter than one year,
as 0.5, based on values tor stable strontium/calcium
although the fall-out duiing this period may correlate
ratiosin average Japanese soil and diet.s4 Data obtainedwith the annual fall-out rate.
+,I,~)
mayintheUnited States indicated that DF( b ) Some plants have leaves at the base of the stem,
be about unity.46 A general approach, by using stable
or a horizontal mat of roots, which may persist for sevstrontium/calcium ratios in average rock and soil anderal years and prevent the SrS0 fall-out from passing
in human bones, has given the value 0.07 k 0.01 forto the soil. If the growing parts of the plant derive SrS0
DF (soil + human bone),*7 although this value will vary acfrom such a persistent stem base or root mat, the approcording to the type of diet.
priate averaging period for the fall-out rate may need
to be several years. Since, at the present time, the fallConce~ztrationsof Sfl0itz foodstuffs
out deposited during the last four years is nearly equal
38. Data submitted to the Committee on concentrato the total fall-out deposit. the formula given above may
tions of SrsO in different foodstuffs are collected in
fail to distinguish between uptake from a stem base ortable XVI. The data show a wide range, caused both byroot mat on the one .hand and from the accumulated
geographic and seasonal effects. Only selected data aredeposit present in the soil on the other.
thesefore meaningful if one wants to examine the in( c ) The uptake of Sr9@fromthe soil is likely to becreaseof the concentration with time. Some such data
Influenced somewhat by the amount of available calcium
for milk are collected in table V. Analysis has sholm
In the soil. There are indications that in soils which arethat dried and fluid milk and cream and skimmed mi&very deficient in available calcium, the root uptake offrom the same whole mill; sample have the same SrsO/S P o may be greater than from high total calcium soils.22 calcium
ratio.48
and that on such soils the possible formation of root mats
49. Cereals and vegetables, as a rule, show higher conflay also enhance the uptake. The foliar uptalce of SrsO
centrations of Sr90 than milk and milk products, as
1s not, however. influenced in this way by soil calcium.
shown in table VI.
The proportions of S P Otaken up through leaves andthrough roots will therefore depend on the calcium
Calciiir~zsozcrces itz diet=esgiven in reference 43 were calculated using experi50. If the dietary habits of a population are k n o \ ~ nmental data from a shorter period. They differ byiabout 10 per
cent from the values above.
with respect to the main sources of calicum and also the&$;fzizs,

1
1

conceatration of Sr" in the var-ious foodstuffs, the daily
uptdie of SP" from vegetation to human bone can b?
computed, using discrimination factors for the different
steps in the food-chains as given in table III.D3B
Table VII, submitted by the Food and Agriculture Organization in consultation with the World HealthOrganization, gives some data on dietary habits in different countries. Additional data from some of these countries support the values. 2313013415* It should be pointed outthat there are only a few countries from which suitabledata were a ~ a i l a b l e . ~ ~TABLE
V. AVERAGE
CONCE~TRATIOS OF Sr90 IN MEE(IN S.U.) I N SOME SELECTED AREAS
Canada6 stations*. ...................
U.K.
Somersetb.
U.S..4.
Perry, N. Y. (Jan.-Dec.). ......
(Apr.-Dec.). ...... 1.1
New York City (Jan.-Dec.) ....
Uune-Dec.).. .. 1.4
Stzte College, Miss. (hfay-Sept.)
Columbus. \iiisc. (Jan.-Oct.). ..
(Mayact.) ...
Mandan, No. Dak. (Jan~Dec.)(May-Dec.) .

...................

.

5.0

6.2 48,49

4.1 4.4

5.1 22,30

1.9 3.3 3.9
2.2 3.7 4.0
2.7
4.5
3.7
5.0
3.8 4.8
3.7 4.2
2.6 4.0 5.3
9.2 16
7.2 9.1 22

Stable sfrorttizt?nsources in diet
52. Some data on the content of stable strontium invarious types of food are also available and are summarized in table VIII.

TABLE
VI 11. AVER~GE
STABLE STROh'TIUM CONTENT92

IN VARIOUS TYPES OF FOODS

92

Cereals and vegetables.. ............
Milk and milk products .............
Marine fish.. ......................
Fresh water fish.. ..................

92
92
92

COXCENTRATIONSOF S F xx (S.U.)
CEREALS AND VEGETABLES

Japan
Rice, white.. .... 49 (36,62)
Rice, brown.. ... 154 (81-250)
Wheat, flour.. ...
Wheat, brown.
Soviet Union
Wheat and rye. . 69 (28-140)
United Kingdom
Vegetables. .....
United States
Different cereals.
14 (4-38)
Vegetables*. ....
8 (1-29)

..

IX

23
53
162 (153,170)

TABLEIX. AVER~GE
DAILY INTAKE OF CALCIUM,
STABLE STRONTICYI AND Sr90 IN ADULTDIET M USITEDKINGDOBI~~

1 1 (6-35)

9 (1-23)

30

FOO~

33q

Milk ...........
Flour and bread*.A11 other foods..

Per tapila avcrogc daily inlckc, m; calciirm

84

52
109
264
53
56
370

510
5 70
i 80
20
32
2 60
585

.S!ublc strmliunr:+toke, M / ~ C Y

SrW intake

667
332
200
1199

193
714
526
1433

3.64
0.66
2.35
6.65

F W / ~ ~ Y* Fortified with mineral calcium.

54. Wide variation czn be expected because of different food habits and living conditions. as illustrated by
con~putationsirom Japan?' They show that whereas the
majority of the population have an average daily intake
of 3.3 to 5.8 ppc SrQO
per day, there is a substantial number of people, who either eat unpolished brown rice ordrink and prepare food with unfiltered rainwater, xvhich
may cause a daily intake of 23 to 26 ppc SreOper day.
Sfd0it! Izlcirrarr bone
55. The nleasurements of SrgO concentrations inhuman bone give the data that are most needed for theestimation of present risks f r o 3 fall-out. The interpretation of bone SreOresults is complicated by four irnportant facrors, which \\-ill be discussed in the following
paragraphs.

IS THE A V E R ~ G E DIETS OF A FEWSELECTED C O ~ - T R I E S ~ ~Ccrcals. lr~eloblcs, Alilk oad nrilk
LIC.
prodrrcls

CaIcium inlakc,
mg/dcy

TOTAL

TABLE
'1711. SOMEPRINCIPAL SOURCES OF CALCIW~

Argentina ...........
Australia ............
Canada.. ...........
Japan ..............
Ph~hppincs..........
Union of South .Africa
United Kingdom.. ...

22,23
20, 22,48
23
23

Daily intake of SrOOiw ntnn
53. Daily intake of Srs"as been reported from someplaces. Table IX shows data from the United Kingdom,
together with data on stable calcium and strontium
intake.

* The samples were frozen vegetables from food plants.

Cou~~try

2
0.3
3
1

These data show that the stable strontium/calcium ratioof certain foods may be up to ten times higher than inmilk and milk products. Therefore milk may not be themain source of stable strontium in diet although it may
be the main source of calcium (see table IX).

* hlonthly data for each station are compared with data fromthe same month in the two years, altogether 57 values used.
b Median values.

TABLE
171.

in the different countries. The main contribution to thehuman diets vary widely from one country to another,uld there are wide variations within the same country inaccordance with many general and local differences ix1
food supplies, dietary habits and economic conditions.51
Milk and milk products are the major source o i calcium
intake in most Western countries (giving about 70-85
per cent of the total calcium), whereas they plzy a very
minor role in nlost of the countries in Asia and Africa,
where other foods such as cereals, vegetables and also
fish and marine products are the principal sources ofcalcium in the average diets. Moreover, certain foods
not originally rich in calcium are fortified by mineral
calcium in many countries.

Fish and maritic
pr,,,l,

12
106

-

7
12

51. The data in table VII should only be taken to
indicate the order of magnitude of the calciuill supplies106( 1 ) L)ue to lag in contamination of calcium sources
human bone is not yet in equilibrium with thewith SrgO,
environment. T o correlate the SrSOcontent of humanbone with the contamination level of the environment
and to predict future risks, it is necessary to know how
close the system bone-environment is to equilibrium. For
this purpose stable stronti~immeasurements are veiyuseful.
(2) If SrS0were unevenly distributed in the humanskeleton the measurement of a single bone \\-ould not be
representative of the average skeleton value.
( 3 ) Uneven distribution of SPO within the bonewould also make the relevant dose computation dific~dt.
(4) The average Sr90 content of bone may also varywith age.

The importo?tce of the stable stro)ztitrnz deterncilzation
56. Using the stable strontium/calci~im ratios in different steps of the food-chains and in bone, it is possible
to determine the discrimination factorsDS5and computethe equilibrium concentration in bone. The determination of stable strontium in bone can be done by spectographf7vS3*j4or by activation
The reported
values diifer somewhat, and this may partly be =plainedby a small but significant difference observed from one
100 pglocality to the next.47 An average of 450
strontium/gram calcium has been found using 756 samples from all over the world." Investigations in Canada
and the United Kingdom have given average values from
290 to 370 pg strontium/gram calcium using a limited
number of samples (16 to 35).2"40150 Young children
apparently have somewhat lower strontium concentrations in bone than a d ~ l t s , which* ~ ~ ~should~
be expected
as a result of foetal discrimination against strontium.3s

trations in young children may be in equilibrium with
their current diet, although the amount of boae contaminated at this concentration may well be only afraction of the whole skeleton. Correction for non-unidistribution is not, however, required if
fornlity of SrDO
the concentration in young children is used as an indication of the masimunl concentrations being reached in
new bone deposited in older children or adults.
(b) Any change in source of calcium intake may involve an alteration of Srw level in this intake and thus
in bone that is currently being formed. An important
instance arises in young clilidren. whose bone calcium
will have been derived from three different sources :(i) From the mother during gestation ;(ii) From the mother's milk during maternal
feeding ;(iii) From the subsecluent dietary sources.

60. Some indication may be given as to the importanceof these factors. Calcium derived during gestat:ion appears at present to be somewhat lower in SrgOlevels(about one half) than the dlild's subsequent diet, since
the level in the bones of stillborn children is rather lessthan in children 1 to 2 years old (table X). The SPO
content of the bones of a child o i 2 years would be only
slightly lowered for this reason since at this age only
about 15-20 per cent of the bone calcium and associatedSrgOwill have been derived during g e s t a t i ~ n . ~ ~+SrO0 d,istribzctiotz in diferent botles of the skeletopc
57. The problem of non-uniformity in the distribution of stable strontium in different bones in the skeletonof man has also been investigated by stable strontium
measurements. It seems that there is a uniform clistribution,4i*5awhich should mean that the distribution of S P O
should also be uniform when the skeleton has reachedequilibrium with a contaminated environment. This has
been confirmed for goats fed by Ca4%nd Sf19 over an
extended period,s6 and by measurements on the distribution of SrBOin cow's bones." In man, hon~ever,there
are experiments showing non-uniformity by single injections of double tracers arid also in the SPOdistribution at present in a d ~ l t s . ~ ~ J ~Uniformity of SrgOdistn'brrtioa in bone
58. I t seems clear that SroOwould be distributed uniformly with calcium throughout the bones of a child
whose calcium intake had been contaminated with SrgO
at constant concentration during the whole of its life
since, in these circumstances, all bone formed would bederived from calcium of equal SraOcontent.
59. Non-uniform deposition would arise frotll two
main causes :(a) A progressive change in the SroOcontaminationof dietary sources will lead to a corresponding change.
in S P Olevel of new deposits of bone, which contain themost sensitive cells. With rising dietary levels, the bone
. concentrations in young children will indicate the current:' dietary conditions. Much of the bone of older children
and of adults will, however, be contaminated at lower- levels corresponding to the lower levels in diets ofearlier years. In this sense, the maximtun bone concen-

61. Maternal milk contains about 40 per cent of thelevel of SrgOin the diet of the mother.93 Since about 25
per cent or less of the bone of a 2-year-old child. previously breastfed for half a year, will have been derived
from maternal milk, this factor would only lower the
average bone S P O level by about 15 per cent or lessfrom an equilibrium condition with the diet.58

62. Thus the highest radiation doses delivered to bonefrom radiostrontium are likely to be those in the newbone, that is at present being laid down in children
aged over 1 year. If the concentration remains constant,the absolute quantity of strontium in the body increases
with the size of the skeleton up to 30 years, and on theassumption of a linear dose effect relationship, theprobability of somatic mutation in bone-marrow cells
increases with the size of the skeleton.
The probletn of computing skeletolr dose from SrOO
63. As a first approximation, SrgOwill be considered
to be uniformly distributed in the skeleton and it will
be assumed that the whole radiated energy is absorbedby the bone. The mean particle energy of the pair S P O
and YgOis 1.13 MevSS,so that a skeleton containing Ig
calcium per 7g bone will receive an average dose rate incompact bone of 2.7 mrem/year per strontium unit.''I n the skeleton about 10 to 13 per cent is spongious bone.
having a dose rate of about 0.9 mrem/year per strontium
unit. The average dose rate to the compact and spongious
bone of 2.5 mrenl/year will be used in the follow~ng
calc~1ations.~~~~~
64. The bone marrow dose from Sfl0 deposited in thebone will be lower than the bone dose, depending on thesize of the marrow cavity. A calculation of a mean marrow dose is therefore a very complex p r ~ b l e r n . ~ "I n- ~ ~the following it will be assumed that 1 strontium unit willcause a mean bone marrow dose rate of 1 rnrem/yyar.
The true value of the mean marrow dose** mtght
P$The computation of the mean marrow dose is difficult andapproximate only.

1TABLEX.

- ~ V E R ~ G CONCENTRATIONEO F SrgOI N MAN (STRONTIUM UXITS)'
Canada*Unikd Iiingdum'l+Fnilcd Stalc+I'.b

Age Group19561957

1956

1957

1955-1956

19361957

Stillborn to 1 month.. .......................
I month to 1 year.. .........................
1 year to 5 years.. ..........................
5 years to 20 years. .........................
More than 20 years. ........................

0.7 (3)
1.6 (2)2.1 (1)0.1 (1)0.4 (3)0.44 (5)0 2 0 (11)0.83 (13)0.25 (12)0.11 (5)0.55 (42)
1.1 (19)
1.2 (17)0.45 (19)0.1 (1)0.56 (10)0.26 (17)0.07 (137)0.67 (30)0.54 (32)0.07 (62)" T h e number of samples in each age group is given inparentheses.

Including a few data from North America outside the UnitedStates.
-4ge group 0 to 5 years.

however, be as low as 0.5 or as high as 2 mrem/year
per strontium unit."
65. It should be emphasized that bone marrow cells
which are almost surrounded by bone will receive doses
which may be qua1 to those in compact bone. Taking
into account all causes for non-uniformity, i.e. the nonunifornl deposition in the mineralized zones, the variation in bone layer widths and geometrical factors(comers), the bone marrow level is probably five times
the figures quoted above.

gamma-emitting daughter product, BalS', which can be
determined using gamma-spectroscopy, as can
The large difference in energy of the gamma rays emitted from Cs13' (0.66 Mev) and K40 (1.46 blev) makes
the discrimination adequate even ~vithcrystal detectorsof low energy resolution. Radiochemical methods arealso in use ior separation of caesium from othermaterial.E15
72. The present burden of Cs137in man can be determined in vivo with whole body spectrometry o r gamma
spectro~copy.~'~Large liquid scintillators have the advantage of being geometrically efficient, but the energy
resolution is relatively poor. Sodium iodide crystals
have good energy resolution, but even with the largest
crystals available, the counting rate is not as high aswith the large liquid scintillators. To obtain the masimum of information, both types of counter seemConcentratiorr of SF0 in l r m z
66. The knowledge of average values is not sufficient
for risk evaluation and individual data are extremely
useful. I t is emphasized that data on bone concentrations
should be accompanied by the following information:( a ) Date of death or biopsy ;( b ) Age at death or biopsy;(c) Precise origin :(d) I n case of children : methods of feeding.
67. Not all the data obtained so far include complete
information, and further studies are required. Table X
gives some of the bone concentrations measured in different countries (see also table XVII).
.

IV. &I3'-4s A N IKTERXAL SOURCE

68. The similarity behveen the nature of the precursors, half-lives and fission ~ie'ldsof SroOand CS'~'suggests that the distribution of these two isotopes issimilar in fall-out. On the other hand, their different
chemical properties make their behavour in food-chains
and in the body different.
69. Cs13' is poorly taken up from soil by
Therefore, the contamination of food sources should
depend largely on fall-out rate. The biological half-lifeof caesium is comparatively short (about 140 days inmanas and 20 days in cowa6), thus indicating that thelevel of the isotope in the human body will approach
equilibrium with the environment relatively quickly.
70. Cs13' concentrations are often expressed by the
C~'~'/potassium ratio. Some evidence exists. however,that the metabolism and routes of entry into the humanbody of these elements are to some degree different. For
example, in man, the biological half-life of potassium(35 days)6i is apparently shorter than that of caesium.
An analogy of Srso/calcium ratios should therefore not
be implied.

Concentration of Cs'$' i n foodstr~fs
73. As in the case of SrBOit should be possible torelate the Cs13' burden in man to the concentration in
the diet. In some areas (i.e. the United States), milk
contributes about 50 per cent of the human uptakea5and can therefore be used for comparative purposes.
During 1956-1957, milk in different countries showeda general CS'~' concentration of 20 to 70 ppc Csla7/g
p ~ t a s s i u m . " ~ ~ The~ ' ~wide~ ~ 'range~ ~ ~is~partly~ ~ caused
by variation ~irithgeo raphic locality. Measurement ofrice in Japan 1956-195 showed a concentration of about
50,upc CsIS7/g potassium.

5

Daily intake of C.P7 in nrart
74. Estimations of daily intake of Cs13' have been
made for Japan and the United States, giving about 30
to 50 ppc C ~ ' ~ ~ / d a yBecause. * ~ ~ ~of~the short biologicalhalf-life for Csla7,variations in the diet will change theCs13' level in man rapidly. With the constant concentration in the diet, the equilibrium burden in man isreached in about two years.
Concentrations of Csl$' in mart
75. The measurements of CslS7in man show a rangeof 25 to 70 ppc
potassium in the north temperatezone during 1956-1957 with an average of about 35 ppc
shortly after
Cs137/g p o t a s s i ~ m .During~ ~ ~ ~ periods~
tests, a slight increase has been o b s e n ~ e d .Concentra~~tions in the diet and in man are apparently rather similar,
which is unespected because oi the longer biologicalhalf-life of caesium as compared to potassium.G5

AfctJtod~for J~teanirenterztof corlcerztratio~rsof CsJJ7
Dose rate frofrt CsJS7in ltzail
71. bleasurements of concentrations of CsX3'can bemade without radiochemical separations. Cs137 has a
76. Since the average potassium content of a standard man (70 kg body weight) is about 150 g,67*60*i0*Higher mean marrow doses are possible and higher doses
the average
gonad dose rate amounts to about
in small foci of bone can be expected.

to the mean residence time of the tropospheric fall-out
1 mrem/year (ranging from about 0.5 to 2 mrern/year) .G5( 3 weeks), gives a dose contribution that is less than
Uniform distribution of caesium in soft tissue is assumed as is indicated by stable caesium n~easurements.~~ 10 per cent of the dose from SF9.
83. Data from measurements in Canada. show thepresence of Srs9in bone from man and animds, as given
77. Fall-out from the troposphere consists mainly of
in table XI.
short-lived isotopes and the dose contributions are thereTABLEXI. CONCESTR~TIOSSOF SrS9 AND Sr9O
fore primarily dependent on fall-out rate rather thar.
ET B O S E ~ ~on accumulated deposit. The latitudes where the tropob p c per g calcium)
spheric fall-out is deposited are mainly determined by
the latitude of the test sites. The doses from tropospheric
Sainpk aitd do& of death
A cc
SrSQ
Srgo
fall-out material vary with geographic location rough!y
Human
bone
in the same manner as the dose from stratospheric
December 1956.. ...... 5 months
5.110.6
1.8rt0.2
fall-out.
December 1956.. ...... 10 months
3.7*0.4
1.4k0.2
November 1956.. ...... 22 months
5.7i0.3
3.8=0.2
External Soilrces
Cow bone
78. The tropospheric material has an observed mean
October 1956.. ........ Foetal
144
8.6
residence time of two to four weeks1 and although it is
October 1956.. ........ 3 weeks
28.3
5.3
deposited intermittently during the year. a certain deOctober 1956.. ........ 4 weeks
43.4
5.1
posit of short-lived activities is built up and maintained.
October 1956.. ........ 6 years
15.6
8.1
The reported values indicate that a level of short-lived
October 1956.. ........ 13 years
18.7
3.8
radioactivity is maintained at about 50 to 200/mc/km2
lugust 1956.. ........ Old
6.3
3.3(See table XIV). Allowing a factor of 10 for shielding
August 1956.. ........ Old
8.4
6.9
and weathering and assuming an average y-energy ofabout 0.5 &Ievl6,the annual gonad and mean bone mar1"'
art ifztertzal source
row dose should be of the order of 0.25 to l mrem/84.
bIeasurementsof 113' are oi interest because ofyear.D"the selective concentration of iodine by the thyroid
Infernal Sources
glands of mm. and animals. The nonnal human thyroid
weighs 20-35 g and contains about 10 to 15 mg of stable
79. The air concentration of fission products at
iodine. All soft tissue has small amounts of stable iodine
ground level has been reported to be about 10-'5c/l
and blood plasma contains about 0.05 pg/a3.i5 The
during 1956 to 1957 (See table XVI). Assuming that
effective half-life of Il3' in the body is very close to thethis material has the same composition as the fall-out,radioactive half-life, 8 days.='
the annual dose resulting from inhalation has been computed'? using data for retention, volume of inhaled air,85, Since 1954, many laboratories have measured
weight of critical organs, etc., based on 1.C.R.P.activities offrom fall-out in human and cattle
criteria.Bi The annual doses, according to the calculathyroid^.^^-^^ The thyroid samples obtained from autoptions, are :sies are counted with scintillation counters calibrated
against 1131standards. In some cases the results are
Whole body dose .................. 0.2 mremcorrected using values from muscle measurements toLung dose (if material soluble) ..... 0.1 mrem
eliminate the K40 and CslJ7contributions.
(if material insoluble) ... 1.5 mrem
Thyroid dose ..................... 0.6 mrem
86. Apparently the cattle contamination is from two
Bone dose (Sre9,SrnO,Bal*) ........ 0.15 mremsources : inhalation and feeding on contaminated pasAverage bone marrow dose (SPg, SrgO,
tures. Restllts obtained by feeding cattle on fresh fodder
Bal'O) ......................... 0.05 mrem
or with barn fodder during the same periods suggest
Average gut dose .................. 0.03 mremthat 70 per cent of the IIS1 uptake is from intestinal
a b s o r p t i ~ nbut
. ~ ~there are other experiments that indiSflo and Bawo as intertral sotrrces
cate both higheP1 (up to 95 per cent) and lowerTi per80. Dose contribution from short-lived activities cancentage from this route of entry.
be introduced through food-chains when the food has not
87. Results of measurements of the IIS1content inbeen stored for a long time. Storage of food reduces thecattlethyroids from various laboratories show a large
activity of short-lived isotopes, which makes it very
spread of values. Neglecting high values from areas neardifficult. if not impossible, to give world-wide average
test sites, average results for cattle from difierent geoannual doses from tropospheric material.
graphical locations are comparable. and are of the order
81. I t has been reported that SP9/Sreo activity ratiosof 1 to 100 ppc/g thyroid for the period May 1955 to thein milk show fluctuations in the range 1 to 25.20*22*48*'0~
end of 1956.m1T8O n account of the short half-life, IX3'
is*74 There are marked seasonal variations, largely deconcentrations in thyroids vary with time as related topendent on whether the cows were on pasture. Thus theweapon test^.'^^^^
average S P 9 concentration in milk has been reported as
88. 1131activities in human thyroids are lower than
3 to 12 ppc SP9/g calcium in January to April.
in those of cattle from the same area and show A s s
whereas it was of the order of 100 to 150 ppc SPs/g
spread in the values. Considering only the IIS1actlvlhes
calcium in September and October in Canada in bothfrom a group of barn-fed cattle and correcting for dif1956 and 1957. The SroOconcentration was all the time
ferent respiratory volumes, values similar to those ofof the order or' 4 to 8 ppc SPo/g calci~m.'~*'~
11unlan thyroids are obtained.80 This supports the idea
83. computation of the relative doses from the twothat the human 1131intake is through inhalation. I nisotopes, using the range of values observed in milk forsome areas of the United States away from test sites. thethe Srs9/Srg0ratios, show that the doses from S P W v e1131 concentrations in human thyroids averaged aboutrise to a bone dose ranging from about 1 to 20 per cent
4 ppc/g thyroid during May 1955.'O The human thyroidsof that from SPO.f Ball0 in the amount that corresponds
measured were mostly from adults (more than 50 Yearsold). but a few samples from persons of different agesiA biological half-life of strontium of 11 years is used?'
-

b

i

-

suggested that the 1131activity increased slightly withage.8o The human thyroid concentrations also vary withtime according to weapon test periods. I t is therefore
difficult to estimate the integral thyroid dose over a
period of time.
89. Considering the linear dimensions of the normal
thyroid gland, it can be computed that the gamma contribution to the average thyroid dose is about 10 per centof the beta contribution.82 Integrating the data for theUnited States, excluding areas immediately adjacent totest sites, average doses of the order of 5 rnrem/year
are found in man for the years 1955 and 1956.'O Dosefrom IIs1in soft tissues is of the order of lo4 times the
thyroid dose.D84Therefore the average annual gonaddose in the United States for the years 1955 and 1956
was of the order of p rem.
90. In areas near test sites, short-lived iodine isotopes
will reach the thyroids. From the half-lives and averageenergies of these isotopes, the thyroid dose delivered canbe computed as 4 times the dose from IIS1if radioiodine
is inhaled about 10 hours after the nudear explosion,83
but after 10 days the contribution is negligible.

m. ESTIVWIONO F DOSES FROU FUTLRE FALL-OUT
91. Data on present fall-out rates and accumulated
deposits and the human burden of fission products
allow the estimation of present dose rates. However, forevaluation of future genetic and somatic effects it isrequired to estimate the 30-year and 70-year doses. Thisestimation can of course be based on computations onlyof future fall-out rate and deposit and not on experimental data.,.It is possible, however, to make these computations using available data and certain assumptions
which have at present little if any support in physicaldata. The results must therefore be considered only inconnexion with these assumptions and necessarily cannot
be any more valid than these.
92. Once the values for the future average world-wide
fall-out rate and deposit have been calculated, the next
step is to evaluate the doses received by human beings.
This requires calculations based on factors, some ofwhich are uncertain and others which cannot be generalized for the world's population, such as agriculturd conditions and practices or living and dietary habits.
93. Owing to all these faciors the evaluation of doses
is rather uncertain. Furthermore, no indiczition. based on
experiments, can be given as to the degree of uncertainty
involved in the evaluations, but an attempt has been
made to choose the more pessimistic of the possible
alternative assumptions, and the over-all calculations
may therefore overestimate the doses to be expectedfrom future fall-out.
Estir~latiotzof fall-oui rate and deposit in the future
94. A major part of the long-lived components of fallout arises from the stratospheric resen-oir, which isbuilt up by "high yield e s p l ~ s i o n s " .I~t ~has been reported that asout 10 per cent of the deposited Srg0comest ~areas~ ~ ~far from test sites
from tropospheric f a l l - ~ uin(Sweden and Unitcd Kingdom). In the United States
the contribution is estimated to be about 30 per cent."
which may be taken as representative for areas relatively
dose to test sites. Only a small error, therefore, is introduced in considering that all the Sr" fall-out arises fromthe stratospheric resen-oir. As Cs13' and SrgOhave approsimately the same half-life and fission yield. andsimilar gaseous precursors in the fission chain. thefollowing evaluation will be assumed to apply for bothisotopes.

95. The material balance of SPOin the stratosphereearth system can be described by the following generalequations :where:
n is the injection rate of Sr90 into the stratosphereper unit area (mc/km2*year). (n is as a convention
assumed t o be uniform for all the earth's surface.
This assumption implies a relatively fast latitudinal
stratospheric mixing.)
0 (t) is the Sr90 content of the stratosphere, expressed per unit area (mc/km2).
Fr(t) is the world-wide average fall-out rate of Sr90
per unit area (mc/km2. year).
Fd(t) is the world-wide average accumulated depositof Sr9O per unit area (mc/krnZ).
X is the disintegration constant of Sr90 (0.025/
year).
96. These equations do not imply any particular relation between the stratospheric content and the fall-out
rate. nor do they imply any specific function for thevariation of 11 with time. The equations, therefore, cannot be fully resolved. At present, data on n are notavailable to the Committee. The computations will therefore be carried out for hypothetical cases of future
values for 11. Equation ( 5 ) implies that no leaching or
weathering occurs.
97. Analysis of fall-out material has shown that Sre0
can remain in the stratosphere for many years before
being deposited on the earth. The depletion mechanismof the stratospheric reservoir is not yet adequately
known. I t has been estimated from measurement of fallout rate and stratospheric content that the annual SrgO
fall-out is about 12 per cent of the stratospheric c ~ n t e n t . ~This annual fraction corresponds to a mean residence
time of about 8 years, which is in agreement with a valueof 10 k 5 years derived from unpublished data.87 The
concept of a constant fractional removal per year of thestratospheric content is inconsistent with ~neteorologicalprinciple. However, nothing better can be offered atpresent. If the concept is to be used, a mean residence
time of about 5 years appears to be the best value anda reasonable upper limit is about 10 years.84 The lattervalue has been used in the calculations to follo\v. since
it tends to yield results on the pessimistic side.
98. For the calculations it will be introduced asworking hypothesis that the annual fraction does notchange with time:
Fr(t) = k Q(t)where k = O.l/yea_r. I t can b_e seen that all the following equations for F,(t) and Fd(t) that depend on thevalue of k will give higher results for lower vziues of k*.
99. As the radioactive material is in the form of
microscopic particles of various sizes, it might be espected that the residence time of this material in thestratosphere \\rill be a function of the size spectrum of
the particles. This has importance especially in the eventthat no new material is introduced into the stratosphere.
because the depletion would then continuously change
the size distribution.
*Using k = 0.2/year in the follo~vingconputztions gives
doses that are 0 to 10 per cent lolver than those obtained using
k = O.l/year.

100. I t is now possible to presknt a model in which
equations (4) and (5) can be integrated. The hypothesesof the model are the following :I

mc/km2

III

1. year( a ) -All the SrSOfall-out comes from the stratosphericreservoir ;( b ) The fall-out rate is proportional to the stratospheric content ;(c) The SrsOdeposited on the earth is not acted uponby weathering effects or leaching :(d) The injection rate of SrS0into the stratosphere 12
will be constant in the future. Two hypothetical cases
giving two different values of tz will be discussed below.
101. The general solutions of equations (4) and ( 5 ) ,using equation ( 6 ) ,are :Fr(0) and Fd(0) are the values

I.

1

I

part of year are encircled.

Case 1: The tests stop ai the end of 1958
102. This implies that n = 0 for any subsequent time.
Using this relation, equations (7) and (8) will be :Fr(t) = Fr(0) e -ck + A)t(9)F'.(t)

1

1954
1955
1956
1957
Figure 2. Fall-out rate of S P determined by radiochemical
analysis.g*ll.l5~~~~**
Values obtained by extrapolation of data forfor the fall-out rate and accumulated deposit at the time
t = 0, which in the following will be taken as the endof 1958.

for the stratospheric depletion. This might have been thesituation during the last four years, as illustrated infigure 2. From equations (4) and (6) it follows that:

Fr(0) (e+ -e-(k +A)t) (10)= Fd(0)Using this relation, equations (7) and (8) will be:
Fr(t) = F,(O)
(15)
Fr(o)
(1 - e -At)
Fd(t) = Fd(o)e -At(1 6)

Equations (9) and (10) show that the fall-out rate decreases exponentially from the moment of interruptionof tests, while the fall-out deposit increases, goes througha maximum at a time:1
Fr(o) (k A)
tmDr= - lnk(Fa(0) F,(o)/k)k~

+

+ ,-

+

If the tests go on indefinitely, Fd(t) will reach anequilibrium value of:Fa(=) = Fr(0)(17)(about 13 years after tests stop) and then decreases,
eventually with the half-life SroO,X

The 90 per cent equilibrium value will be reached inabout 70 years.
105. Asszimptwn (b).;The period from the beginningof 1954 t o the end of 1958has been chosenDlo3because
the values of Fr(t) and F,(t) were small before 1954
and the error introduced assuming both to be equal t ozero would be small. The estimation of an average fl
for the period 1954 to 1958 inclusive implies in ourmodel computing a constant n such that it wsuld Prod-uce, in five years, the observed values of Fr(0) andFd(0) a t the end of:1958.
106. The total amount of Sr90 in the environment

Case 2: Tests continue
103. For the calculations of future fall-out rate anddeposit t ~ assumptionsoare used: (a) the rate of fallout of Srgo will remain in the future a t the constantvalue observed for the last four years, or (b) the rateof injection of Sr" into the stratosphere will remait] inthe future a t a value equal to the mean value for theyears 1954 to 1958 inclusive. If tests are stopped a t any
subsequent time T, then Fr(t) and Fd(t) would fromthat momenton,with either assumption,be determinedb y the equations:~ X ) ( t - T)
Fr(t) = F , ( T ) ~ - ( +(12)

F (T) (e -A(C
Fd(t) = F , ( T ) ~-A(' - TI + Lke-(k i A ) ( t - T ,1

is F,(t)- TI -+ Q(t) = F,(t) + +F. (t) Therefore.

(averagefor the period 1954 to 1958) is an Z determined by! .
F (0) = Ti (I - e-Ar)
Fd(o)
(18)

(13)

++

104. Asstimption (a). In the model adopted. thisassumption implies that Q will remain at an equilibrium
value, which has been caused by large initial injections,follo\ved by a constant injection rate that compensates--.

where 7 is 5 years, and Fr(0) and FdO) arerate and deposit a t the end of 1958. Under tfilsassump*>
tion the solution of equations (7) and (8) Is:-~'
5

111

-

F,(t) = F,(o)e -ck

+

fik
k+X
+-

Fd(t) = F,(o)~-Y +-108. The world-wide average of the fall-out rate of
SrgOwas estimated from the latitude distribution curve,
figureI t was assumed that the fall-out rates at thepoles were zero. As measurements seem to indicatethat the fall-out rate has been fairly constant over thelast four years (see figure 2),D104the rate of 1.5 mc/km2.
year obtained from the data from 1956 and 1957 has also
been assumed valid for 1958.

(( e - ~ t - e - ~ +4t)

k

X

-A

+f(m+me-(k+"')(20)
If tests go on indefinitely F,(t) and Fd(t) will reachthe equilibrium values:-

109. The world-wide average of the accumulated fallout deposit of SrsOhas been obtained from soil, pot and
The values obtained were
gummed film data.5~9-13~'0~"2'3
extrapolated to the end of 1958 using the quoted value
1.5 mc/km2.year for the average fall-out rate: giving as
an average about 5 mc/km2 as the average accumulated
deposit at the end of 1958.

Ti

Fd(") =

h(li + A)
The 90 per cent equilibrium values will be reached inabout Is' and 100 years, respectively.

110. Population weighted averages have been calculated using the same data as in paragraphs 108 and 109,
and the latitudinal distribution of the world's population
as obtained from a detailed population map.s6At present,
the maximum fall-out level occurs at the same latitude
as the maximum population density and the population
weighted averages for fall-out rate and deposit are atpresent higher than the area weighted averages by afactor of about 2. I t is possible that this may change inthe future and that in the event of cessation of tests it
may approach unity. However. no allowance for thispossible reduction has been made in the present calcula-

Values of F,(O) and Fa(0)107. I t is dii3cult iron1 the available data to computea world-wide fall-out rate and deposit, partly because
large areas of the earth are insufficiently covered by the
net-work of stations collecting data and partly because
the different stations and laboratories do not all operatewith comparable collection and evaluation methods. The
estimation is especially difficult for the fall-out deposit,
as many stations have only operated for less than
two years.

Population weighted
fall-out rate of srgO
Fr (t)
8.0'

7.0

mc/krn2-.

rate-fromtests up to the end of 1958year

- ---- rate.according assumption atp..................rate according to assumption b
Time for cessation of'tests.........:.................................
at fie end of fie year given
Equilibrium value'

6.8 mc/km2. year

for the different curves.

------------Equilibrium value
3.0 mc/km

2

.

year

I

I

80

90

I

I

100 -t years

Population weighted accumulated fall-out deposit
Fd (t)
mc/km2
150

*.f

*:

~ ' k ~ u i l i b r i u valuem
272 mc/km2

:

:t'
.*.

:a
.

t

z

,.+-

:

*+*.

:
:

.SO

-

0

.+-*

19sa

t

t

-

L

CIP----

Equilibrium value
120 mc/km2

I

I

I

.

1

I

I

r

10

20

30.

40

50

60

70

tions.** The population weighted values of the fall-out
rate and of the accumulated deposit at the elid of 1958
are accordingly taken as :F,(O) = 3 mc/km2*year

Methods for dose estimutions***111. The equations derived above give the variationof the fall-out rate and deposit with time for the different cases studied (see figures 3 and 4). The computationof doses to human beings also requires information on
the behaviour of SrsOand Cs13' in the food-chain, andthis introduces new uncertainties. The main information
required is the extent to which the dose rate is correlated
to fall-out rate and to fall-out deposit and the values ofthese correlation factors. At present the available information is insufficient and has to be complemented bysome assumptions.
- F o r population weighted avenge fall-out rate and accumu(wiUlout
rated deposit the symbols F r ( f ) and R ( t ) arebar). As F,(0) and Fa(0) are a factor of 2 higher than F,(O)and Fd(0), respectively, it can be seen from equations (7). (a),(14) and (18) that also F,(t) and Fa(t) are a factor of 2
higher t i a n F,(t) and Fd(t).
the dose estimations population weighted average-Forfall-out rate and accumulated deposit F,(t) and Fd(t) will
be used.

r
80

I

I

I

90

loo

t years4
i112. I n the following paragraphs dose computations
will be considered for:( a ) =ternal irradiation of gonads caused by CP":(b) Internal irradiation of gonads caused by CS'~';(c) Internal irradiation of bone marrow caused
by Sreo.
In addition to the cases of (1) cessation of tests at theend of 1958 and (2) continuation of tests until equilibrium is reached, the doses for cases of (3) interruptionof tests at different times in the future are also given as
percentages of the equilibrium dose.
External irradiation of g o d s caused by CsJS'
shows that the exposure rate
113. Equationfrom external irradiation is proportional to the accumulated fall-out deposit :I = c X E-t X FTd(t)(1)
atake care
Takingof shielding, leaching and weathering effects, the dose
rate is given by:dD(23)(;if)e= c x cl x E, X Fz(t) = g. X FI(t)mrad. km2
Here c a 0.1 year.mc*i\?Iev and c1 will be assumed tobe 0.1.D'5 In the case of exposure from Cs'" the113

1deposit according to assumpti03 a

Time for cessation of tests at the end of
the year given for the different curves.

f*.
::....*...

:

100- - --

deposit.from tests up to the end of 1958.............. deposit according to assumption b

+
:
'

-

-

be used for EY is 0.92 X 0.89 X 0.661 NIev (92 percent of the disintegrations give y-ral-s of energy 0.661
Mev and of these y-rays 11 per cent are converted.)T h e dose rate from deposited Csln is therefore:($)a=ge~Fd(t)mrenl/year ior a fall-out rate of 1 mc/km2. If in the
future the dose rate is proportional to the fall-out rate,
then:

(z),

= g, X F,(t) = 0.3 X F,(t)=0.005 X Fd(t) mren~/year (24)(26)

Total irradiation of gonads caused by Csln

Iniernal irrdiatit'cnz of g o d s catlsed by CslS7
114. The human burden of CslSi at present depends
primarily on the fall-out rate of ~s thus giving~
the dose rate:

115. The total dose rate for the gonads from Csl37 is
dD
~
~
,
~
~glFr(t) ~(2 7)
d t = geFd(t)(25)

The 30-year doses for the two assumed injection rates(assumptions a and b) and for the different cases considered for cessation of tests are therefore given by+

Calculations from exoerimental data show that the average gonad dose rate >mounts to about 1 mrem/year in
the United Kingdom and the United States during 1956
and 1Fj7.DiaThe observed fall-out rate of SrBOin thosecountries was about 3 mcfim2 during the same years
Assuming the same fall-out rate for(figure 2)
Cs13' as for Sfl0 (probably an underestimate), the dose
rate due to internal irradiation from Cs13' is 0.3
TABLEXI I.

so

3o

+

ao

DIO = /%t= g . f ~ ~ ( t ) d t g l / ~ ~ ( t ) d t (28)7"0"0The equations for Fd(t) and F,(t) to be inserted in t h edifferent cases can be found elsewhere in annex D,
identified by their numbers as given in table XII.

EQUATIOSSFOR USE IN FORMULAS (28), (34) Ah'D (35)F ,(1)

FdCl)

Asrumpl. a

Tests stop end of 1958..

.....

Assumpl. b

Assumpl. a

Assumpr. b

(9)

(10)

Tests stop end of 1968, T=10(16) and (13) (20) and (13)(15) and (12)Tests stop end of 1978, T = 20

(16) and (13) (20) and (13)(15) and (1 2)(19) and (12)Tests stop end of 1988, T = 30

(16) and (13) (20) and (13)(1 5) and (1 2)(19) and (12)

(1 5)

(19)

. .

Tests continue.. .... . .. . .

(1 6)

The 30-year doses beconle functions of the time for thestart of integration, i.e., of the time of birth of the persons concerned. It can be shown that the maximum occurs for persons born at the end of 1958.7 If tests
continue, the maximum doses occur when equilibrium
conditions are reached for fall-out rate and deposit.
I n order to compute the total of individuals geneticallyaffected by a given series of tests, it is necessary to add
up the D,, values for all population groups born insuccessive years. Because the doses are almost completely delivered over only a few decades for tests ceasing at the end of 1958, these sums of D,, values overall successive population groups are satisfactorily approximated for the present purpose by the maximum
values of D,, in table XIII, if these are assumed toapply over a period of 30 years.

116. Any estimation of future levels of Sr" in humanbone is extremely difficult because it depends both on
estimations of the SrOOfall-out rate and deposit in the
future and on estimations of how these levels will influin bone. This last problem
ence the concentration of SrgO
is particularly uncertain, as the uptake in the bone isvery much dependent on the dietary habits and the foodi T h i s becomes slightly incorrect when the cessation date islater than about 1978. Even for cessation in 1988, however, theapproximation is good if the tropospheric contribution to thedoses is added.
* T h e bone marrow dose from external and internal Cs"'
can be calculated by integration of equation (27) over 70 years.
The dose contribution is of the order of 10 per cent or less thanthat from SrDDin bone and has accordingly been neglected intable XIII.

(20)(19) and (12)technology in a given r e g i ~ n . ~ ~As" - ~it ~has* been discussed in paragraphs 37 to 36: the uptake of SrgOin
different plants at different locations may be dependent
on a number of factors, such as fall-out rate, accumulated deposit and the amount of available calcium in soil.
117. The following paragraphs provide calculationsof the equilibrium diet-bone concentrations to be expected in humans subsisting on each of two foods :milk
and rice. In actual practice, a population does not subsist
entirely on either milk or rice, and these calculations
should. therefore, be accepted as approsimations basedon conditions which would not in practice be realized.
118. The concentration of SrgOin human bone in equilibrium with contatnirlated food can be estimated using
formula (3) in paragraph 30 if milk is the main sourceof calcium in the diet:
Cff = DF(mllkbone) X Cp,f = DF(mllk+bane)
X (a>f.l(Fd 3fd) $ bMfd)
where C z is the concentration of Sr90 in newly formedbne,
the discrimination factor from milkbone, DF(t o bone and the rest of the symbols are as in paragraph 40.
119. I t will be assumed that, in the future, theaccumulated deposit, Fd(t), will be the determining
factor for the milk ~ontamination.~'6Using a valueof ah, intermediate between those determined for
Perry, N. 17.,Ddand in the United IXingd~rn,~"andDFbak -bone) = 0.5 (table III),D" a simplified equation will be:
Cfr 0.15 X Fd(t)(30)
where Cr: is given in strontium units myhen Fd(t) isin rnc/km2.

-

+-

-

Estimated doses
124. Table XI11 shows the results of the computations for the different cases. The numbers should only
be considered in connexion with ail the assumptions anduncertain factors discussed in the preceding and following paragraphs.
125. For the estimations of future fall-out rate andaccumulated deposit the regional values can be expected
to differ by a factor of about 4?, to 2 depending mainly
upon latitude.D1s In some areas of the world the tropospheric fall-out may tend to raise the upper limit of thisrange, especially in the vicinity of test sites.
126. The uncertainties in the calculations of doses,
based on the estimated fall-out levels, may be considerable, but are difficult to evaluate because of insufficient experimental data. It seems: however, that theexperimental data indicate an uncertainty in the percapita mean marrow doses of a factor of about 3
merely because of regional variations in the conversion
factors from fall-out deposit to bone concentration of
Spo.D11e-i20

120. I n the cases where rice is the main source of

SF0 in the diet, a formula has been derived to cover
the rather unusual method of farming this grain in

T a.~ a n where,most of the ~ l a n tmaterial from earlier"cropsis ploughed down in B homogeneously cultivatedsoil.3'

Cg is the concentration of SrqOin newly formed bone.
DF{=II, ~ . I , I and DF(d, -bane), the discrimination factors from soil t o nce and from rice to bone, are taken
as 0.5 and 0.17 r e ~ p e c t i v e l y ~ ~A
~ .is~ "the. amount ofavailable calcium in the soil, approximately 95 X 10"
g/km2 (with outer limits approximately 30 X lo6 and230 X lo6g/km2)."The formula will in this case be:
CE 0.9 X Fd(t)(32)
where CE is given in strontium units when Fd is in
rnc/krn2.
121. I t is evident that the equations (30) and (32)for concentrations of SroOin bone are uncertain. The
neglect of folizr retention and of sources o i Sro0otherthan milk tend to give bone concentrations that are too
low, especially in the immediate future. I t must be
VII. CALCULATIOXOF BIOLOGICAL EFFECTS**
emphasized that the bone concentrations are calculated
127. The frequency of certain possible consequences
only for newly formedofradiation has been estimated on the following basis :122. The mean bone marrow dose is assumed to be
1 mrem/year for a bone concentration of 1 strontium
Leilkernia, assunling a litlear dose respome
unit.DE4 Therefore the dose rate in bone from SrBO
relationslzip arld ?LO threshold
will be :128. In this case, the number of individuals affectedannually ( R , ) is calmlated from the appropriate 70year mean narrow dose (D,,), the dose effect constantwhere CBis the conce~ltrationof Srw in nexvly formed( K , ) for leukemia as derived in annes G , paragraphbone, as given by equations (30) and (32) for the two
50, and the assumed world population ( P ) , and dividing
diets considered. The 70-year doses for the two asby 70 to give a mean annual rate. Thus:
sumed injection rates (assumptions a and b), and forthe different cases considered for cessation of tests are
therefore obtained by integration over 70 years ofequation (33), giving, for the hypothetic milk diet:I<, is here calculated on the ass~unptionthat a leukemia
70
incidence of 1.5 cases per million per year per rem continues after each element oi radiation exposure for the(DTo), = 0.15
Fd(t) d t
(34)
remaining life of the individual, or for an average period0of 35 years in a population living to age 70. K1 has thus
and for the hypothetical rice diet:a value of 52 cases per million per rem.
70( a ) I n estimating on this basis leukemia ascribable(35)(Dm):=
0.9
Fd(t) d t
to natural radiation, Dr0is 7 rem (annex C. table S X V )0and R1 is calculated for P = 3 X lo9and 5 X 10". giving
values of R , of 15,SOO and 26.200. (The natural occurThe equations for F d ( t ) to be inserted in the different
rence of leulcemia is calculated on a basis of 50 deaths
cases can be found elsewhere in annex D, identified byper million per year.)
their numbers as given in table XII. The doses are calculated for persons born at the end of 1958, which give( b ) Leukemia ascribable to fall-out from weapon
approximately the mz~imum70-~eardoses. If tests contests, if such tests stop in 1958. is calculated withtinue, however, the masimurn doses occur when equiP = 3 X lo9 and with values of 0.16 and 0.96 for Dio.
librium conditions are reached for accumulated deposit,
These are estimates for milk and for rice diets (table
and have accordingly been calculated for that case.
X I I I ) , and would correspond to incidences of 360 and
2,160 cases per year. Because most of the dose is actually123. T o use the equations (30) and (32) in thesedelivered during a few decades, the total of induced
computations implies the assumption that the wholecases would about equal 70R, and so \i-ould be 25900 toskeleton has. at any time, the same concentration of
151,000.
SrSOas bone which is newly formed at that time. The
Committee is aware that this assumption is not consistent(c) Leukemia attributable to fall-out in equilibriumwith the rather long biological half-lives o i calcium andconditions reached after prolonged testing is calculated
strontium. It is, however. a satisfactory approximation
for P = 5 X 10" The values of D,, (table XIII) range
for the purpose of the present calculations. which itfrom 1.3 rem under assumption a and with a nflE diet,greatly simplifies. 3Ioreover, this extreme assumption
to 17 rem under assumption b and with a rice diet,tends to over-estimate the average 70-year dose, and so
giving- - incidences of 4,880 and a,S00 cases Per Yearthe calculations may be taken as an upper limit for those**For the purpose of table TI, chapter VII, of the report the
population cohorts receiving the maximuin 70-year
finures calculated in the following pragraphs have been
exposure.
r&nded off.

1
j

1.

i

11

DOSES FROM STRATOSPHERIC FALL-OUT' (computed from population weighted \vorldTABLE
XIII. ESTIMATED
wide average values of stratospheric fall-out rate and d e p ~ s i t ) ~&wfically signifianl dare:
Jiarinurm faany 3Sfa-yearperiod (rcm)

Per capita mean m a n d dose:
Afaximum for ony 7 b j c a r prriod ( r m )Estimates for countries
drrisirrg most ofd i c u r y colcium from milk*

LVeapon tesrs cease a t end of 195.8.. ....................
Weapon tests continue until equilibrium is reached
in about a hundred pears. ....................

0.(110Eslirna:6sfor countries
derivirrg most of
dietary cokiam from rice=

0.16

0.96

Assump. ad

Assump. bd

Assum*. ad

Assurr~p.bd

Assunrp. od

Assump. bd

0.045

0.10

1.3

2.8

7.5

17

Eslirnnlcd perccntoges of fkc maximrorr doses for conlitrued =capon tesls

Weapon tests cease:1958 ......................................
1968 ........................................
1978 ........................................
1988......................................
Weapon tests continue ..........................

Assump. ad

Assump. bd

Assump. od

Assxmp. bd

22
45
63
72
100

10
33
55
62
100

13
24
34
42
100

6
16
26
35
1GO

* The methods used for calculation of these doses are given inparagraphs 91 to 123.
b Regional values may difier by a factor of l / j to 2 tram theestimated population weighted world-wide average values becauseof the latitudinal variation of fall-out rate and deposit. In someareas of the world the tropospheric fall-out may tend to raise
the upper limit of this range, especially in the vicinity of test sites.
The extenr to which these estimates apply to populations ofdilierent dietary habits and to those living in areas of differingsoil conditions is discussed in paragraphs 116121.
Assumption a is that the injection rate is such as t o m a i n d n
a constant fall-out rate of S F and Csls, whereas assumption bis that nneapon tests equivalenr in release and stratospheric injection of fisslon products to the whole sequence of weapon tests
from the beginning of 1954 to the end of 1958 will be repeateda t constant rate. This second assumption d l give an equilibrium
value for the fall-out rate and deposit a proximately a factor of
2 higher than that calculated by using t i e first assumption.

Estimates for milk diet with assumption b and for rice
diet with assumption a are 10.500 and 28,200 cases per
year.

This report affords only very incomplete evidence as tothe likely variation of individual marrow doses fromthe mean values, and 110 estimate is given or' the way inwhich the risk of leukemia might increase once a threshold dose was exceeded. These results, on the hypothesisthat a 300 renl threshold exists, therefore give only ageneral indication of the relative hazards in different
circumstances.

@

Leukemia, assuming a threshold of 400 rent
129. On this hypothesis, cases of leukemia might result if the 70-year dose exceeded 400 r at any point in
the marrow. The maximum dose in marrow might. in asmall cavity, equal that in surrounding bone; and it ispossible that such bone might, owing to irregularities inmineralization, receive a dose oi up to twice the meanbone dose. which in turn is estimated to be about 2.5
times the mean marrow dose (taking a mean bone doseof 2.5 mrem per year per strontium unit*** and a mean
marrow dose of 1 mrem per year per strontium unit).
The maximum marroiv dose might thus equal 5 times themean marrow dose.
( a ) With natural radiation, a threshold of 400 rem
will only be exceeded in an individual receiving 400/7,
o r 57 times the normal D,, of 7 rem.
( b ) With fall-out from tests ending in 1958, the mean
marrow doses of 0.16 and 0.96 on milk and rice dietscorrespond to maximum marrow doses of 0.80 and 4.8.
The threshold urould thus be exceeded by individuals
receiving 400/0.8 and 400/4.8. or 500 and 83 times,
the average values of D;,.
( c ) Under equilibrium conditions of fall-out after
prolonged continuation of tests, the mean 70-year marrow doses would range from 1.3 to 17 rem, and thecorresponding maximum marrow doses would be 6.5 and85 rem. A threshold of 400 rem would thus be esceeded
by individuals receiving 62 times the average value formilk diet with assumption a, and 4.7 times this value forrice diet with assumption b.
-A mean osteocyte dose of 2.5 mrem per year per strontium
unit has also been used for the purpose of the calc~~lationsofthe numbers given in note to table 11, chapter I I I .

Major genetic-def ects
130. For the purpose of these calculations it is assumed that, by the time any mutations currently occurring came to be expressed as damage in the population,
the world population would have become stabilized at
P = 5 X lo0,half of whom were below the mean age ofreproduction.
The total number of births would be 5 X 109/70 and aof these would be affected by major genetic
part (Kg)
defects (annex H, table XI), the value of K, being
assumed from present experience to lie between 1 and
4 per cent of all births. The normal occurrence of such
defects would thus be from 715,000 to 2,860,000 per
year.
The total number of births affected by a 30-year
gonad dose D 30 is given by
Daa
P

I

where D? is the representative doubling dose and isassumed to lie in the range 10 to 100 rem. Under
equilibrium conditions, the evaluated rate of suchbirths would be
I3 30
P- x KgX(38)I32
2 X 30(a) Radiation from ?zatz~ralsources
For D 3 0 = 3 rem (annex B, table XXV) the rate of

I!
I

3
affected births is

2.5 X 109

(1 t o 4)X(10 to 100)

X

100

30

= 25,000 to 1,000,000 per year.

(b) Fall-out, tests slopping i n 1958
T h e total gonad dose is about equal to the nlasimum
30-year dose of 0.01 rem (table X I I I ) so that the total
0.01
number of afiected births is(1 to 4)X

X-

(10 to 100)
2.5 X 109 = 2,500 to 100,000 births.

100

No rate can appropriately be given since these births
will occur over a period prolonged beyond the 30-year
interval over which the dose is integrated.
(c) Fall-out, tests continuing for a prolonged period

The values of Dso are 0.06 rem and 0.12 rem on
assumption a and b (table XIII)i, giving rates ofRates are thus 500 to 20,000 on assumption a and1000 to 40,000 on assumption b. Rates can here be
given since equilibrium conditions are postulated.

VIII. NOTEON IXFORLIATION WNMENT
131. A document (A/AC.82/INF.3) entitled: "Anapproach to a general method of computing doses andeffects from fall-out" was prepared by the Secretariatof the United Nations in collaboration with a group of
experts of the Committee, as a working paper. It wascompleted just before the Committee's last session (9-14June, 1958). The Committee has not had sufficient time
to study and eventually to accept this work which wasconsidered to be of substantial scientific interest; it has
decided to make this paper available because it will be
useful to scientists engaged in calculations of gonad orbone marrow doses and their biological effects.07

1. Marley, W. G., The long-range fall-out from nuclear test explosions. Medical Research Council(U.K.) : The hazard to man of nuclear and allied
radiations. London (1956), p. 121-125. U N document A/AC.82/G/R.2.
2. Stewart, N. G., Crooks, R. N., and Fisher, E. M. R.,
UN doc~mentA/AC..82/G/R.20.
3. Martell, E. A.. U N document ,4/AC.82/G/R.21.
4. Doke, T.,
document A/AC.82/G.R.136.
5. Kurchatov, B. V., UN document A/AC.82/G/R.
199.
6. Aler, B., Bjijrnerstedt. R., Edvarson, K., and Lcw,
K., UX document A/AC.82/G/R.l5. Part 9.
7- Hvinden. T., UN doiument G A C . S ~ / G / R . I ~ ~ .
8. Hunter, H. F. and Ballou, N. E., Nucleonics 9, No.
5. a - 7 ( 1951).
9. Law,K. and'~dvarson,K., UN document A/AC.
82/G/R. 146.
t T h e values for the 30-year dose have been corrected forfall-out in accordance with paragraphs 78 and 79,
a value of 0.5 mrem/year for the period of testing.

10. Eisenbud, M. and Harley, J. H.. United States
Atomic Energy Commission report HASL-24(1958).
11. Hardy, Jr.. E. P., United States Atomic Energy
Commission report HASL-22 (1958).
12. Eisenbud, hl., ~!Jeas~rrer~restof stro~xtizt~it-90
i j z geopltysical and biological nzaterial. Hearings before
the special subcommittee on radiation of the Joint
Committee on Atomic Energy, Congress of theUnited States. Part 1. 554-575 (1957). and UN
document A/-%C.82/G/R. 130.
13. Stewart, N. G., Osmond, R. G. D.. Crooks, R. N.,
and Fisher, E. 11.. UN document A/-lC.82/G/
R.143.
14. Nussis, N.. Henkel. C., and Menis, M., UN document A/AC.82/G/R.157.
15. Miyaka, Y., Sugiura, Y., Saruhashi, K., and Kanazawa, T., U N document A/AC.82/G/R.172.
16. Hallden, N. A., and Harley, J. H., United States
Atomic Energy Commission report NYO-4859(1957), and UN document A/AC.82/INF.1.
17. Aler, B. and Herrlander, C. J., U N document A/
AC.82/G/R.150.
18. Neun~an,W. F. and Neuman,. M. W.: Cltefiiicd
dynarrzics of bone ntineral. Monograph. Universityof Chicago Press (1958).
19. Klechkovsky, V. M., editor, UN document A/AC.
82/G/R.4 1.
20. Harley, J. H.. Hardy, Jr., E. P., Whitney, I. B., andEisenbud, M., UN document A/AC.82/G/R.93.
21. Martell, E. A., U N document A/AC.82/G/R.l53.
22. Bryant, F. J., Chamberlain, A. C., Morgan, A., andSpicer, G. S., U N document A/AC.82/G/R.126.
23. Hiyama, Y., editor. UN document A/AC.82/G/
R.141 and Add. 1.
24. Comar. C. L., Scott Russel, R., and Wasserman,
R. H.. Science 126,485-492 (1957).
25. Alexander. G. V.,Nusbaum, R. E., and 3lacDonald,
N. S., J. Biol. Chem. 218,911-919 (1956).
26. Bryant, F. J., Chamberlain, A. C., Morgan, A., andSpicer, G. S., U N document A/AC.82/G/R.30.
27. Comar, C. L., Whitney. I. B., and Lengemann,
F. W., Proc. Soc. Esptl. Biol. Med. 88, 232-236(1955).
28. Comar. C. L., Wasserman, R. H., and Nold. M. H.,
Proc. Soc. Esp. Biol. hfed. 92, 959-863 (1956).
29. Comar, C. L., Wasserman. R. H., Znlberg. S.. andAndrew, G. A., Proc. Soc. Exptl. Biol. Med. 95,
386-391 (1957).
30. Chamberlain, A. C., Spicer, G. S.. and Webb,
hl. S. W., British Medical Journal, in press.
31. Harrison, G. E.. Raymond, W. H. A. and Tretheway, H. C., Clin. Sci. 14, 681-695 (1935).
32.Spencer, H., Laszlo, D., and Brothers, &I., J- Cli*.
Invest. 36,680-688 (1957).
33. Eckelman, W. R., Kulp. J. L., and Schulert, A- R.1
Science 127, 266-274 (1958).
34. Hiyama, Y. : UN document A / A c . ~ z / G / R . ~ ~ ~ 35. Wasserman, R. H.. Lengemann, F-W., and Comar*
C. L.. J. Dairy Science, in press.
36. Comar. C. L. and Wasseman, I?. H., Progress in
Nuclear Energy. Series VI. Biological SciencesPergamon Press, Ltd., London, 1, 153-196 (1956)-

11737. Libby, W. F..Proc. Nati. Acad. Sci. 42, 365-390( 1956), and UN document A/.4C.S2/G/R.131,
38. Wassennan, R. H., Comar, C. L.. Nold, M. II., andLengemann. F. W., Am. J. Physiol. 189, 91-97(1957).
39. Leng&ann, F. W., Proc. Soc. Esptl. Biol. Med.
94, 64-66 (1957).
40. Talrnage, I?. V., S~hoole~r.
J. C., and Comar, C. L.,
Proc. Soc. Esptl. Eiol. Med. 9 j , 413-417 (1957).
41. Bauer. G. C. H., Carisson, A., and Lindquist, B.,
Acta Phpsiol. Scand. 35, 56-66 (1955).
42. 3lacDonald. N. S., Noyes, P.. and Lorick, P. C.,
Am. J. Physiol. 188. 131-136 (1957).
43. Tajima. E., Science, in press.
4-4. Communicated by W. G. Marley. 1958.
45. Food and Agriculture Organization of the United
Nations, U N document A/AC.82/G/R.165.
46. Menzel, R.: Private communication, as given inreference 47.
47. Thurber, D. L., Kulp, J. L., Hodges, E., Gast, P. M.,
and Wampler, J. hil., Science, in press.
48. Canada: Report to the United Nations ScientificCommittee on the Effects of Atomic Radiation. UN
document A/AC.82/G/R.99.
49. Grummitt, W. E. and Mar, P. G.. Atomic Energy ofCanada Limited and Department of National Healthand Welfare Report CRC 786 (1958).
50. Kulp. J. L. and Slakter. R., Science, 125, 85-86( 1958).
51. Food and Agriculture Organization of the United
Kations, TJiV document A/-4C.82/G/R.f6/Rev.l.
52. Argentina : Report to the United Nations ScientificCommittee on the Effects of Atomic Radiation. UN
document A/AC.82/G/R.127.
53. I-Iodges, R. H., MacDonald, N. S.. Nusbaum. R. E.,
Steams. R., Ezmirlian. F.?Spain. P.. and McArthur,
C.. J. Biol. Chem. 185, 519-524 (1950).
54. Turekian, K. K. and Kulp, J. L:, science 124, 405407 (1956).
55. Harrison. G. E. and Raymond, W. H. A., J. Nucl.
Energy, 290-298 (1955).
, R., Biochem. J. 67, 10456. Sowden. E. M. arid ~ t i c hS.
109 (1957).
57. Killp, J. L:. Eckelmann. W. R.. and Schulert, A. R..
Science 125, 219-225 (1957) and U N document
A/AC.82/G/R.91.
58. M i t c h e l l , ~ .H.. Hamilton. T. S . Steggerda. F. R..
and Beau, H. Mr.,J. Biol. Chem. 158, 625-637(1945).
59. Hine, G. J. and Bro\vnelI. G. L.. editors : Radiafiorr
dosilrretry. Academic Press, Inc., New York (1956),
p. 899.
60. Hindmarsh, M., Lamerton. L. F., O~ven.AS.. Spiers.
F.W., and Vaughan, J., EN document A/AC.82/
G/R.114.
61. Engstrom. A., Bjornerstedt. R., Clemedson. C.-J..
and Nelson. A. :B o w a d radiostroltrizcuz. Alrnquist
and Miiksell, Stocld~olm; John Wiiley and Son, Inc.
New York (1958).
62. Communicated by R. Bjornerstedt and A. Engstrom, 1958.
63. Co~nrnunicatedby 1W. G. Marley. 1958.
64. Nishita. H.. Ken-alewsky. B. W..
Steen, A. J. andLarson. K. H.. Soil Sci. M, 317-326 (1956).

65. Anderson, E. C., Schuch, R. L., Fisher, TV. R., andLangham, JV., Science 125, 1273-1278 (1957) andUN document A/AC.82/G/R.123.
46. Hood. S. L. and Comar, C. L. University of Tennessee Report ORO-91 (1953), also Arch. Eiochem.
Biophys. 45,423-433 ( 1953).
67. International Commission on Radiological Protection, Recommendations, revised December 1, 1954.
Brit. J. Radiol. Suppl. 6 (1955).
68. Burch, P. R. J., Brit. J. of Radiol. Suppl. 7, 20-26( 1957).
69. Rundo, J., U N document A/AC.82/G/R. 167.
70. Sievert, R. M., Proc. Int. Conf. Peaceful Uses
Atomic Energy, United Nations 13,187-195 (1956).
71. Communicated by I. H. Tipton. 1958.
72. Com~nunicatedby W. G. Marley and E. E. Pochin,
1958.
73. Bergh, H., Finstad, G.. Lund, L.. Michelson, O., andOttar. B., U N document A/AC.82/G/R.113.
74. Bergh, 13.. Finstad. G., Lund. L.. Michelson. O., andOttar. B., Norwegian Defence Research Establishment Revorts No. KIR-173/57, KIR-176/57, KIR75. Best C. H. and Taylor, N. B.: Tlze physiologicalbasis of medical practice, 6 ed. The Williams andllilkins Comp., Baltimore (1955) p. 806-817.
76. Egypt: Preliminary Report to the United Nations
Scientific Committee on the Effects of Atomic Radiation. UN document -4/AC.82/G/R.46.
77. Gunther, R. L. and Jones, H. B., United States
Atomic Energy Commission report UCRL-2689 andaddendum, ( 1954).
78. White, M. R. and Dobson. E. L., United States
Atomic Energy Commission report UCRL-3355(1956).
79. Van IIiddelsworth,L., Science 123,982-983 (1956).
80. Comar. C. L.. Trum. 13. F., Kuhn 111.U.S.G., Wassennan, R. H., Nold, M. M., and Schooley, J. C.,
Science 126, 16-18 (1957).
81. Communicated by W. G. Marley, 1958.
82. Hine, G. J. and Brownell, G. L., editors: Radiation
dosimetry. Academic Press Inc., New York (1956)
p. 865.
83. Dunning, G. If..
Nucleonics 14, No. 2.38-41 (1956).
84. Communicated by L. Machta, representative of theWorld Meteorological Organization to the United
Nations Committee on the Effects of Atomic Radiation. 1958.
85. Lewis. C.: T h e Atlzerican Oxford Atlas. Oxford
University Press, New York (1951).
86. Sievert, R. M.. Gustafsson, S., and Rylander. C. G.,
Arkiv for fysik 12,481-499 (1957) and U N document A/AC.82/G/R.147.
87. Alba. F., Brodjr, T.. Palacios. A., and Tejera. -4..
U N document A/AC.82/G/R.187.
88. Data submitted by the United States delegation to
the United Nations Committee on the Effects ofAtomic Radiation ( 1958).
89. Data sublllitted by the United Kingdom delegation
to the United Nations Colnrnittee on the EEects ofAtomic Radiation (1958).
90. Data submitted by the Japanese delegation to theUnited Nations Committee on the Effects of Atomic
Radiation (1958).

91. Communicated by W. E. Grurnmitt, 19%.
92. Hardy. Jr.. E. P., United States Atonlic EnergyCoinmission Report HASL-38 ( 193.3).
93. Communicated by J. H. Harley. 19%.
A.. ~ a ~ e r aR.,s .Palacios, A.,
91. Alba A., F..
Rickards C., G., Tejera R.. -4.. and de Velarde.
E. G. B., UN document A/AC.82/G/R.l&.

rod^:^.

TABLE
XIV.
ConnLry

Argcnlina

Denmark

Sampling method. ...........

Stainlesssteel pot

Plate

Sampling period.. ........... I month......

96. Russell, R. S. and Alilbourn. G. 31.. Kature. 180,
322-324 ( 1957).
97. UN document A/AC.82/IXF.3. Copies oi thedocument may be obtained bv writing to the United
Nations, X e v ~york 17. N. P.. U.S.A.

E S T E ~ AIRRADI;\TION
LDUE TO FALL-OUT
Mexicofi-clhnlunds

Noway

Srr&n

Uniled Stairs

Gummedfilm

Stainlesssteel pot

Stainlesssteel pot

FunnelGummed film

24 hours (if 1 month or Dust: 24 hrs., 2 to 3 days
morehn0.5 aftereachpre water after
mmpreeipita- cipitationeach precipition is coltation
lected)2 days24 hours

Period of mmwement. ...... Jan. to Sept. J a to Dec.
Totnl accumulatedactivityirom
fall-out (mcjkm2)s...

95. Blok, J.. UN document A/AC.82/G/R.l84.

FranceJapan

Funnel com- Polyethylene
bined with sheet and pory mmed 6lm cclain bay

1957

1956

Aprii 1955 toJuly 1957

ilb

60

50b

4 to Ndays 24 hours
or during
precipitationbhy 19% to &lay1956 to Nov. 1955 to OcL 1958 to A p d 1953 to OcL 1952 toJune 1957
Oat. 1957 Oct. 1957 Sept, 1957 June 1957
June 1957"Infinite plane" exposure during a 30-year period, from thetoW fd-out during the period of measurement ( m d ) .
Factm of redoction due toweathering.

...............

Factor of reduction due toshielding by buildings ......
Total reduction factor..

......

3

7

6*Activity a: the end of t h e period of measurement, comprising local tropospheric a n d stratospheric fall-out deposited duringthat wrinrl.
r--b Extrapolated t o 1 January 1958.

Dose for infinite time. This dose is only slightly different from t h e 30-year dose.
March-October 1957.

d From fall-out during the period

TABLE
XV.

Sr90 FALL-OUT ON THE GROUND-Countrv

dipnfinr

Snmplin: mctho3..

BelgiumPram..... Stainless Aluminium Funnel
steel p3t

potbined mthgummed6lm

Japn

Hmico

N&h&

Polyethylene. .
sheet and

Gummed6lm and

Staidesporcelainpoteteei pot...-.- -,Son'etUnitd Arab
Union o j Socialid
Pd blic
liniledNorwq So& A f r h &publiu($a) Kingdo2
Staideseke] pot

Porcelain
pot

Gauze

GummedFwei

6lm

Linitai
Sfatea(a) Gummedpaper(b) stnitdeb9
steel pot(c) Gal~auized

tray

.UU

.... . 1 nonih~ ~ W d i~r a~ i o d . . .

.

Period d measurement. Jaa-&pt.
1957

24 h o w

24 horn

Dust: U k..
2 to 3 days
water d ~ c r
precipitation
whprecipitstion~p.-Nov.
1967

Apt. 1955- (a) May 1954- hk.-Oci. (a) Julyblar.1956- Jan.-Apr.
1956
July 1957
Aop.1956
1957
1965Jnne 1957(b) Oct. 1956NOT. 1956
June 1957(bl Dec.
1958Nm. 1957

I month. or
a h : each

2 days24 hours

24 hours

24 hours(0) Up to Mar.-Dee.
end 1955
1957(a) JulySepl. 1957

1 month(a) 24 h o r n@) 1 w t - 1 mo(c) 3 to 7 days

May 1 9 w (a) Oct. 1951Apr. 1957
June 195i(b) Feb. 1954Gpt. 1957(c) hiar. 1955Nov. 1957

htethod of determinntionof Sr*.

.............. W.chem. Fhd.chem. Cdcnlation\ (a) CdculaadYi3

tion*(b) Radchem.
analysisdysis

Cdculation*(a) Qlcula-tio~

Cdculation*(b) Radio&em.

Rad.chem. Bad.chem. B3d.cheehem.
andysisnnalyais
adyeis of
dpoOaed poded
smplesssmplesBad.chem.
malysisanal*(a) CalculsLion*[improved)(b) and ( 4Radrhem.

dais
Accumulated d e m i t d
8 P during the priodof measurement (no/hn3 ................

1.4

15

2O
.

8.Ob

0.6

Approx. 5 3

2.4(034.9)0.28(0)l.S(0.8-33)

7 s(a) 6.8(42-21)(a)(c) 9.01
rate of EP( s c l l r m r - yeu)

Fnht

.....

1955: 0.6
1956: 0.7

1954: 1.0
1955: 0.7
1956: 3.8

Using Hunter and Ballou curves 8.
b Assumed a deposit of 0.4 mc/km2 prior to May 1954.
Assumed a deposit of 0.7 mc/km? prior t o May 1954.

* New York City.

Pittsburgh.
Mean value from 4 funnel stations.
Mean value from 8 pot stations.

(a) Appro% Sept. 19562.3
Aw.1951:(b) 2.3
0.9@) 2.8(234.3)

1.4

1954: 2.0
1955: 23
19%: 2.V

1957 3.W(1.9-0.2)

TABLEXVI.

~IISCELWNEOUSDATA ON Sr90
Union ofco~abydrprntinn

Brad

Cwda

Japan

6+ in air a i ground lerel( l e a 4 1 ) ............

YrricoNonmr

Sdm

Xov. 1955 to
Xov. 1956:
53(25-106)'

1956:
4.6
(4.5,4.6)

B F i n milk (lyle/pCa). .. Apt. to June
1957:
34
(3.1, 3.9)

Ftst month
195i:
2.7M.3

1956: 5.0
(lSll.6)
1957: 8 2
(2.5-19.8)

1956: 2.4
(2.1.2.7)
195i: 2.9

Oct. to Dec.
1966:
1.2(0K-l.S)
Od. to Dec.
1957:
3.0(2534

1957: 7.9d
(45-155)

Summerl956:
13b(0.~3-2.0)

S o ~ S ~ i r f Unifrd

Cn'ledLidom

S!a!crMar. to Dee.

dpri1 1952 :o

1955:
60-110&pi.-SOT.
1957:
6.3-100

Ju. 1856:
C

1953: 6.4
(3.0-112)19%: 20(1.0-60)
1955: 41
(3.6-120)
June to Inp.
1956:
75

Feb. to Job

March 1955:

1952
6.0
(3512)

l.i(O.5-2.9)
July 1956:
4.7 (1.9-10)&rmblicr

1953: 14(0.4-24).
1965: 4.8
(0.8-7.5).
1956: 6.9
(2.9-12).

July 1956 to 1965: 3.9
J w 195i:(1.8-6.0
4.9
1956: 5.4
(2.2-8.0)(2.9-103)1956:

vcgebbks
9.4 (1.1-23)
Whiie rice:49 (36.82)
B r o m rice:
154 (81-250)
Rice bran andM
450 @9o-Mo)
195i:
Brmn wheat:
102 (153.170)

wha(Bau:53

Corn. 1956: Dea h m . prom
62(226.6)

195k 4.4(1.E4.9)
1855: 4.:(1.0-11.7)
1956: 2.6
F& 1956 to
196;:

Fdmka
3.4 (0.4-11.4)

Muine:
0.29 (OJ9,0.38)

Calculated from total &activity measurements.

b Preliminary data, probably too low because of the leaching method used (1 M ammonium acetate).

Sampled in October each year.

* In units of @/I.
Grown on normal soil.
' Grown on acid hill soil.
Lowland sheep.
Highland sheep.

1956: 11.0
(8.0439).
526.7-16314
1956: 13.0
(i.5-16.6).
48('24-1W)hCons and
Sheep
1954:33(1.7-7.0)
1955: 7.5 ::(0.51-24)

Country

Japal:

Norway.

Union ofSomct Socialist
Rrpfrblics

Dm. 1956 to
May 1957

Oct. 1956 to
Dec. 1957

Second half1957

4.6 (4.14.6)

0.5
0.8 (0-1.3)
0.7 (0.2-1.1)
0.4 (0.3-0.5)
0.3 (0-0.7)

CasadaPeriod oi measurement.. .. June 1956 toJune 1957
Age Froup
Stiltborn to 1 month.. ...
month to 1 year. ......
1 Year to 5 years.. ......
5 ~ ~ t 0 2 0 y e......
ar~hfore than 20 years.. ...

0.7 (0-1.1)
1.6 (1.4,l.g)
3.1 (0.1-3.8)
0.1
0.4 (0.1-0.6)

0.73 (0.2-1.25)
0.U (0.04-1.73

Ui:ifcd Kingdom

Oct. 1955 to

Dec. 1936
0.44 (0.150.8)
0.70(0.15-1.3)
0.85 (0.51-1.45)
0% 280.15-053)
0.11 (0.064.2)

2.3 (1.6-3.2)b' Preliminary data, determined without using low-level counter.

Cnifcd SIafcs

Jan. toJune 1957

Dec. 1955 toJuly 1956

0.54 (0.44.7)
1.5 (0.9-3.4)
1 3 (0.4,?.2)
0.39 (0.3-0.5)

0.57 (0.45,0.70)
0.83(0.71-0.97)
0.51 (0.10-1.7)
0.47 (0.13-1.4)
0.04 (0.02-0.11)

b Age 0 to 5 years.

TABLE
XVIII. Cs137 FALL-OUT ON TI-IE GROUND(Determined by radiochemical analysis)

CouufrYJapan

Sampling method.. ........................

(a) Precipitation collection

SwcdcnUnited Kingdom

FunnelFunnelSampling period.. .........................

(a) 40 to 8 3 days

4 to 30 days or during
precipitation

3 months

Period 01 measurement. ....................

(a) March to June 1957(b) Aug. 1957

April 1953 to June 1957

Jan. 1956 to hlarch 1957

Accumulated deposit of Csln during the periodof mewurement (mc/kmz) ...................

(b) 6.5.........

(a) 2.3

Fall-out rate of Csln (mc/l:m2.year)

TABLE
XIX.
CaurJryJapan

Period of measurement. ....... 1956 t o 1957

Vegetables and fruit.. .........

(b) Soil

July 1955 to June 1957: 1.3

CslU IS FOODSTUFFS XXD THE IIUM~XT
BODY(In units of ppcCslU/gK)
MexicoNormaySwdcn

Unitui Kincdom

Unifcd .%airs

Dec 1956

1957

1956

June 1956 to July 1957

1956

6.4
(3.3-1 1)

Cereals and rice.. ......
Human body.. ...............

30-60

Human urine.. ...............

34(9-78)In units of ppcCsl~7/l.

11(7.2-14)

T-ABLE
XX. ~'IISCELLANEOUS DATA ON FALL-OUT
CantafryB d g i ~ i n Brazil

Denmurk Smnu

Period of measurement of air 1957 %layto
concentrations of fission
July 1956
products. ................

1956

hlaximum concentration o! 14.8 '. .fission prodacts in air at: ground level (lo-%/I). ....

?1.9b

?dean concentration oi hssion

7.5

1957

Inliu

It&

Japan

Feb. t o Nov. 1956 a) 1955
tob) 1956
Jan. 1958 C) 19.5

Aug. 1956
87b

17.9b

33.P

a) 14.id

A-etherlands N a r a y

Sirdn

Re d l i c(9,)

31ay 1956 Mar. 1956

April 1952
toJa.1956

totoDee. l9.Z Oct. 1957
l?Obb) 177.3.
C) i53.6"
0.5

5.8

10

5.6

products in air at groundlev4 (10-16cll) ............

12.6a) 5.99b) 37.1c) 54.1
Sept 19%

Cantent oi I131 in thyroids ofcatUo bpc/g).

...........

100-800

hfay toSept. 1956
11 (0-129)
Oct. 1956
344 (3-1290)

Average over 1 month.

b Average over 24 hours.

L-,,ifcd
K ; , , ~ ~Appendix

LIST O F SCIENTIFIC EXPERTS
The scientific experts who have taken part in the preparation of the report while attending Committee sessions
as members of national delegations are listed below. The Committee must also express its appreciation to the many
individual scientists not directly connected with national delegations whose voluntary co-operation and good willcontributed in no small measure to the preparation of the report.
ARGENTINA:
Dr. C. Nuiiez (Representative)
Dr. D. J . Beninson
Professor E. Favret
Dr. N. Nussis
Dr. J. A. Olarte
AUSTRALIA:
Dr. C. F. Eddy (Representative-first
Mr. D. J . Stevens (Representative)
Dr. A. R W. Wilson

Dr. A. Halawani (Representative)
Dr. H. T. Daw

session)BELGIUM:
Professor Z. Bacq (Representative)
Mr. R. Boulenger
Dr. M. Errera
Professor F. Twisselman
BRAZIL:
Professor C. Chagas (Repesetrtative)
Dr. B. Gross
Professor N. Libanio
Professor C. Pavan
Father F. X. Roser, S.J.
CANADA:
Dr. E. A, Watkinson (Representative)
Dr. R. K . Appleyard
Dr. P. M. Bird
Dr. W. E. Gnunmitt
Dr. Colin Hunter
Dr. G. H. Josie
Dr. C. A. Mawson
Dr. H. B. Newcombe
Dr. F. D. Sowby
CZECHOSLOVAKIA:
Professor F. Hertik (Representative)
Professor F. BEhounek
Dr. M. HaSek
Dr. L. Novik
Professor V. Sobek
Dr. I. Ulehla
Dr. V. Zelenf

Professor L. Bugnard (Representative)
Dr. A. Allisy
Dr. J. Coursaget
Dr. H. Jammet
Dr. J. Labeyrie
Dr. J. Lejeune

INDIA:
Dr. V. R. Khanolkar (Representative)
Dr. A. R. Gopal-Ayengar
Dr. A. S. Rao
JAPAN :

Dr. M. Tsuzuki (Representative)
Dr. Y. Hiyama
Dr. D. Moriwaki
Dr. K. Murati
Dr. M. Nakaidzumi
Mr. S. Ohta
Dr. N. Saito
Dr. E. Tajima
MEXICO:
Dr. M. Martinez Baez (Representative)
Dr. F. A. Andrade
Dr. H. Zalce

Professor R. M. Sievert (Representative)
Dr. B. A. A. Aler
Dr. R. G. Bjarnerstedt
Professor G. Bonnier
Professor T. 0. Caspersson
Professor C. A. T. Gustafsson
Dr. A. G. A. Nelson* Now in the United Arab Republic.

UNIONOF SOVIETSOCIALISTREPUBLICS:
Professor A. V. Lebedinsky (Representative)
Professor K. K. Aglintsev
Professor B. M. Isaev
Professor P. M. Kireev
Professor A. N. KraevsLy
Professor A. bZ. Kuzin

UNITEDKXNGDOM
OF GREATBRITAINAND
NORTHERNIRELAND
Professor W. V. Mayneord (Represetltativefirst session)
Dr. E. E. Pochin (Represelztative)
Dr. T. C . Carter
Mr. A. C. Chamberlain
Dr. W. G. Marley
Mr. N. G. Stewart

Dr. Shields Warren (Represe~rtative)
Professor G. W. Beadle
Dr. A. M. Brues
Professor J. Crow
Professor Th. Dobzhansky
Dr. C. L. Dunham
Mr. Merril Eisenbud
Professor Sterling Emerson
Professor G. Failla
Dr. J. H. Harley
Dr. J. S. Laughlin
Professor J. V. Nee1
Dr. M. Zelle