REPORT OF THE

UNITED-NAXI-ONS .

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EFFECTS OF !iit}ifffHiADIATION.. : . . .

·'GENERAL ASSEMBLY
OFFICIAL RECORDS : SEVENTEENTH SESSIONSUPPLEMENT No. 16 {A/5216}

New York, 1962

NOTE
Throughout the present report and the annexes thereto, references to theannexes are indicated by a letter followed by a number: the letter denotes the relevant
annex and the number the paragraph therein. Within each annex, references to its
scientific bibliography are indicated by numbers.
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.

h we ut··m,.

ANNEXERADIATION FROM NATURAL SOURCESCONTENTSParagraphs

lNT.RODUCTION ••.• , , ... , , . , ... , .• , .• , , , .....•. , . , • , . . .

1-3

I. CosMic RAYS • • . . . . . . . . . . . • • . . . . . . . . . . . . . • . . . • . 4-18
Nature of radiation ............. , . .. • • .. .. .. . .. • 4-5
Radiation dose-rates • . • . . . . . . . . . . • • . . • . . • . • . . . • . 6-8
Variations with latitude and longitude............ 9-12
Var!a~ons w~th a~titude ......................... 13-14
Vanattons with time ............................ 15-18

II. NATURAL RADIO-ACTIVITY IN THE EARTH'S CRUST.,., 19-31

Paragrop/u

V. NATURAL RADIO-ACTIVITY IN FOODSTUFFS .••......•. 58-66
Total alpha-activity •.....•..••.••.•...••....... 59-60
Radium-226 ..•...••....•.•.••..•........•..•.•• 61-63
Thorium •••.... .. . .•. ..•••. .•. .•. . . .. .. .• . . .•. 64
Pb210, Bi21om and Po210. . • • • • . • • • • • . . • • . • • • . • • • • 65
Potassium-40 • . . . • . • . . . . . . • • . • • • • . • . . . . . . . • • . . . 66

VI. NATURAL RADIO-ACTIVITY IN THE HU!.!AN BODY •• , •. 67-84

Naturally ~ccu_rring radio-active nuclides......... 19
Concentration m common rocks.................. 20
Uranium and thorium ............ ,.............. 21
Radium-226 •.•..•.•..•.•..•..•......•..•..• , . . . 22
Potassium . • . • • . • . . • . . • • • . . • . . . . . . . . • . . • . . • . . . . 23
Rn 222 and Rn 220 in the earth's crust. ...... , •• , . . . . 24
Dose-rates from the earth's crust ..........•. , ..•. 25-31

Total alpha-activity •..•....•. , •••....•..•.•.... 68-69
Radium-226 ••......••....•.....••....••.....•.. 70-74
Thorium . . .•. . . .•. ••..•..••. ..••... .. .. ... .•. • 75
Pb210, Bjnom and Pono......................... 76
Dose-rates for naturally occurring U and Th series 77-78
Potassium-40 . . . . . . . . ... . • . • • • . • . . • . . . • . . . . . . • . . 79-81
Carbon-14 ...................••........••....•. 82-83
Tritium • . .• • • . • • . . ••• . . . . . . . • •• . • . . .. . . .• . . . . . . 84

III. NATURAL RADIO-ACTIVITY IN WATER ............... 32-36

VII. HIGH NATURAL RADIATION :\REAS ..... , .. ,, .. , .•.• 85-93

Public water supplies. • . . . • • . • . . . • • . • . . . • . . . • . . • 33-34
Ocean water, rivers and natural springs... . • . . • . . . 35
Skeletal Ra 228 content due to drinking water...... 36

IV. NATURAL RADIO-ACTIVITY IN THE LOWER ATMOSPHERE 37-57
Rn 2 22 and Rn 22 0 and their decay products ••..•.•.. 37-42
Pb21 0, Bi21om and Pono......................... 43
Carbon-14 •••..•••..•..•.......•.........•..•.. 44-54
Tritium • • • . • . . . • . . . . • . . • . . . . . . . . . . • . . • . • . • • • • . 55-56
Beryllium- and other cosmic ray-produced nuclides • • . . . . . . . . . . . • . . • . . . . . . • . . . . • . • • • • • • • . • • 57

High natural radio-activity in the earth's crust ..•. 86-90
High natural radio-activity in the air • • • • • • . . . . • • • 91
High natural radio-activity in buildings........... 92
High altitude areas .. . • . . • • • .. . . • • • . . . . .. . • • .. . . 93

Vlll. SUMMARY OF EXPOSURE DATA ....•.... ,., ....••... 94-95
TABLESREFERENCES

posed for radiation protection purposes1 • 2 and are generally thought to be rather conservative, particularly inthe case of a-particles and neutrons. For the estimationof biological damage it is quite probable that lower values
are more applicable. For instance, the 1959 ICRP Committee II report3 states the following with regard to the
RBE for a-particles :Introduction

1. The radiation from natural sources at any specificlocation remains relatively constant with time; it does,
however, vary from place to place. Natural radiationarises from two sources-cosmic rays and naturally occurring radio-active materials. While cosmic rays are
predominantly an external source of irradiation, naturally occurring radio-active materials give rise to both
external and internal irradiation of the human body.
A distin~ishing char~cteristic of irradiation by natural
sources is that the entire world population has been e.....:posed to it since the beginning of time and will continue
to be exposed to it in the future.

"Many experiments4 indicate that (REE) a ismuch smaller than 10 for biological damage resulting
from acute exposure-perhaps as small as 1.4--but
for chronic exposures, much higher applicable values
have been reported. 5 Therefore, until more data forchronic exposures are available, it would be unwise touse a value of (REE) a < 10."

.2. The biological. e~ect of ionizing radiation varies
with the type of radiation, and, in order to take this into
account, a weighting factor is used to obtain the tissue
dose in. rem fro?l the corresponding absorbed dose in
r31d. This factor 1s known as the relative biological effectiveness (REE) and the usual definition is given inannex .A .. Ho.wever, the RBE factor for a particular typeof radiation is not a constant, and varies with a numberof other l?arar:ieters such as dose-rate, dose fractionation,
type of biological effect, oxygen tension and temperature.

For low energy electrons of$; 0.03 MeV, Shtukkenberg4
suggests that the REE is 2.8-3.0 (i.e., greater than theusual value of 1.7). when one takes into account thesmaller biological effect produced by chronic irradiation
when compared to a single exposure. In the light of all
the uncertainties, it is thought prudent to use the RBE
values given in annex A in order to estimate the exposure
pattern in man, but to keep in mind that in general thesevalues will be too high (see also annex H). Where possible in the present annex, tissue doses will be given in
rem as well as in rad.

3. The RBE values given in annex A are those pro-207

I. Cosmic rays

made with the Pioneer V space probe have been somewhat enlightening on the behavior of solar protons infree space. The probe encountered outbursts of solar
protons at a distance of about 5 million km from theearth during the period from 27 March to 6 April 1960.
Unlike the radiation belts, the solar particles are not
restricted to a small region of space that could be avoided
or traversed rapidly, but would apparently be encountered throughout the solar system. Consequently, steps
will have to be taken to shield directly against theseparticles in order to achieve manned missions of any
appreciable time duration.
5. The primary particles interact with nuclei of theupper atmosphere, producing secondary radiation, which
consists of mesons, electrons, photons. protons and neutrons-all with a very wide range of energies. Electronsand photons constitute the soft component of the secondary radiation, protons and neutrons the nucleoniccomponent. The primary radiation intensity gradually decreases with decrease in altitude and at about 20 km it
has practically disappeared, so that below this altitude
cosmic radiation is almost entirely secondary in nature.
In the altitude region above 20 km, the proportion of
secondary radiation rapidly decreases until, at about 50
km, the radiation dose-rate is due predominantly to theprimary component, except in the case of the auroral
regions and the inner and outer radiation belts (para. 4).
The increase in cosmic radiation dose-rate with altitude
is such that above about 2 km, cosmic radiation becomesthe major dose-rate contributor in man.

NATURE OF RADIATION

4. Primary cosmic radiation may be divided into
three categories: galactic cosmic radiation, geomagnetically trapped radiation, and solar cosmic radiation.
(a) Galactic cosmic radiation presents a more or lessconstant space environmental factor, and its particle
composition has been quite well determined. Outside theatmosphere at latitudes above 55°, primary cosmic raysof galactic origin consist of 87 per cent protons, 12 percent alpha particles, and 1 per cent heavier nuclei (C, N,
0. Mg, Ca, Fe).1 - 10( b) Geomagnetically trapped radiation is the sec?nd
category. At higher altitu~es, in regions sym~etncal
with regard to the magnetic equator, there exist tyvo
radiation belts containing electrons and protons whichhave been captured by the magnetic field of the earth. 11 - 14
The inner belt begins at about 1,000 km altitude, reaches
a maximum intensity at about 3,000 km and extends
from 30° N to 30° S. The outer belt begins at an altitude
of about 12,000 km, passes through a maximum in~en­sity at about 15,000 km and extends from 60° N to 60 S.
The energy spectrum of the particles in each belt differs
considerably but has not been investigated fully enoughto give an accurate estimate of the radiation dose-rate inthese regions. The dose-rates will be dependent on theamount of shielding assumed and, for the inner radiation
belt, values of 10 and 120 rad per hour have been suggested15• 16 for 1 and 2 g per cm 2 shielding respectively.
Dose rates in the outer belt may be of the order of 10'
rad per hour 17 owing to soft electron bremsstrahlung,but this can be reduced considerably by shielding. A further high intensity field of low energy electrons18•1 9 is tobe found at high latitudes ( > 60°) and altitudes ( > 25km) and is associated with auroral processes.
( c) Solar cosmic radiation is the third major radiation
phenomenon. Large fluxes of protons are observed toreach the vicinity of the earth following severe solar
flares which occur on the surface of the sun. Because of
the potential danger of space travel and because of therelationships to solar physics, magnetic fields, and manygeophysical events, this radiation is under intense study.
Solar cosmic ray events may be divided into two classes:"high energy" and "low energy". During high energy
events a significant number of particles have energies
high enough to produce effects observable by groundlevel neutron monitors, whereas high altitude measurements or riometer measurements are necessary to detect
the low energy events. The high energy events appear to
be much less frequent than those of low energy. Only
five such events were detected during the twenty years
preceding 1959; however, an additional five events havebeen detected during 1959 and 1960, three of which
occurred in one month, November 1960. The low energy events, on the other hand, have been observed tooccur at the rate of ten per year since 1957. The mostintense high-energy outburst of solar protons recorded
to date was observed following the great solar flare of
23 February 1956. Shortly after the beginning of theflare, solar particles with energies of several Bev began
striking the ionosphere. Data available from a numberof flare events seem to indicate that the initial flux
reaching the vicinity of the earth may be monodirectional with the flux, then becoming isotropic after about
the first hour. There is also some evidence that the
spectrum of the initial particles may be considerably
harder than that of those arriving later. Measurements

RADIATION DOSE-RATES

6. The radiation dose-rate due to the ionizing component of cosmic rays is generally estimated by measuring the number of ion pairs per on3 /sec, using an energy
independent ionization chamber, and then converting
this value to the rate of absorption of energy assuming that 34 eV are required to form 1 ion pair. Manymeasurements of this type have been made. These measurements, however, do not take into account the radiation dose-rate due to the neutron component of cosmic
rays, and this must be measured separately. Many measurements of cosmic ray neutron flux have been made but
there are relatively few estimates of the resulting tissue
dose-rate. This is due to the fact that the tissue dose-rate
is very dependent on the neutron energy spectrum20
which is extremely difficult to determine. The cosmic
radiation dose-rate often used as a "base level" is thatat sea level for high altitudes (,...., 70°). There are indications21· 22 that the most reliable figure for the ionizing
component in this region is 1.90-1.96 ion-pairs per
cm 3/sec. which gives a soft tissue and gonad dose-rateof about 28 mrad/y.
7. The cosmic ray neutron component results in atissue dose-rate which. at sea level for middle latitudes,
has been estimated by Patterson et al. 23 using three different type neutron detectors, which could respond todifferent ranges of neutron energy. Patterson's calculations show that the dose-rate from the neutron component of cosmic rays at sea levels is 25 mrem/y. This estimate is the dose-rate at the skin using the values of RBE
established by the United States National Committee on
Radiation Protection and Measures and ignores the absorption of neutrons in building structures and the bodyitself. It has been assumed that there is an average of 10
cm of building materials in roofing materials, timbers
and ceilings, and that the average depth of the gonads andbone-marrow is 4 cm. By applying corrections for the208absorption of the various energies of neutrons, assumingthese materials to be tissue equivalent, and assumingthat the average time spent out of doors is seven hours
a day, the resultant tissue dose-rate is 13 mrem/y. (These
data are based on the depth dose curves for neutrons
given in reference 24.) This is probably more reliable
than the value of 18 mrem/y for sea level at 51° N given
by Tobias19 whose estimate was based on measurements
using a single type neutron detector which did not givea direct measurement of fast neutron flux, the most critical portion of the neutron energy spectrum with regard
to dose-rate considerations. According to Shtukkenberg's25 calculations, the cosmic radiation fast neutron(> 10 MeV) tissue dose-rate at sea level is approximately 10 per cent of the total dose-rate. He suggeststhat the total dose-rate resulting from cosmic radiationis 88 mrem/y, if an RBE value of 10 is assumed for
densely ionizing particles with energies up to 15 MeV,
and 57 mrem/y, if a value of 6.5 is used.

paragraph 4. Figure 1 gives the measured variation ofcosmic radiation dose-rates in mrem per year with altitude for the ionizing component32 at 3° N and 55° N andfor ~e neut\on. component23 in the latitud~ rang~ 28490 N. The significance of curves A and B 1s explainedin paragraph 15.
,. Neutron component (28-490 N)/

A (low solar activity)//

B (blgh solar activity)//~ 1,000j

8. It is therefore suggested that 50 mrem per year
be taken as a typical value for the total cosmic radiation
tissue dose-rate for sea level at middle latitudes. The
value is subject to variations with a number of parameters, as discussed in paragraphs 9-18 below.
VARIATIONS WITH LATITUDE AND LONGITUDE

9. Cosmic ray intensity exhibits a latitude effect whichis due to the earth's magnetic field preventing the incoming primary particles below a certain critical minimum
energy from reaching the earth's atmosphere. This critical cut-off energy decreases with increasing latitude,
the net result being that the cosmic ray intensity at thegeomagnetic equator is lower than at other latitudes.
The intensity remains relatively constant between 15° N
and 15° S, then shows a rapid increase until about 500
latitude, after which it remains practically constant again.
The latitude effect is generally expressed as the percentage increase at 50° over the intensity at the equator.
10. The average value26 for the latitude effect of theionizing component of cosmic radiation at sea level is
10 per cent. The percentage increases slowly to a value ofabout 30 per cent at an altitude of 5 km and then much
more quickly to a value of about 350 per cent at thetransition region (about 20 km) of the atmosphere(para. 15).
11. Since the neutron component of cosmic radiation
includes neutrons produced by interaction with the atmosphere, it also exhibits a large latitude effect. 27 At altitudes from sea level up to about 3 km, the latitude effectis about 150 per cent and at 9 km, is about 250 per cent.
12. Changes in cosmic ray intensity with longitude
are expected to occur2 8 since the magnetic centre of theearth and the geometrical centre do not coincide, themagnetic centre of the earth being approximately 300 km
from the centre of the earth along a line passing approximately through 100 N geomagnetic latitude and 160° E
longitude. The intensity of the ionizing component at
sea level has been found to vary about 5 per cent along
the geomagnetic equator, 29 the effect diminishing at
higher latitudes. 30 The nucleon intensity shows similar
but larger intensity variations with change in longitude.21,a1

lOOL-~~--"10~~~--"20~~~--'30~~---,•0~~~-'50

AlUtude (km)• Sec annex A for comment on RBE values used.

Figure 1. Variation of cosmic radiation level with altitude

14. Typical values for the total cosmic radiation tissue
dose-rates for various altitudes at the equator, 300 and
50° latitude, have been estimated, assuming that Pa~ter­son' s23 results for the neutron component at vanous
altitudes apply to a latitude of 50° and that the latitude
variations are as suggested in paragraphs 10-11 (table I).
VARIATIONS WITH TIME

15. Time variations of cosmic ray intensity result
from a number of causes including solar flares, the 11year solar cycle. the 27-day lunar period, temperaturechanges in the upper layers of the atmosphere, barometric pressure changes and air fronts. The modificationin cosmic ray intensity which is associated with the
11-year cycle33 of solar activity is most pronounced forthe lower part of the energy spectrum of the primarycosmic radiation and is therefore only evident at highaltitudes where it results in a minimum intensity at theper'.od of maximum solar activity. This is illustrated bycurves A and B in figure 1 which show~ 2 the total ionization as a function of altitude in 1954 (curve A) when
the sun was at its lowest ebb in twenty-two years, andin 1937 (curve B), a year of high solar activity.
16. Further variations associated with the sun are
the so-called cosmic ray storms which are of short duration, one day up to a couple of weeks. They start with asudden decrease, or series of decreases, in cosmic rayintensity and are followed by a slow recovery. Thesestorms and decreases in intensity are correlated with the

VARIATIONS WITH ALTITUDE

13. The variation in composition of the cosmic radiation with altitudes up to 50 km has been described in
209number and size of sun spot groups as well as the appearance of solar particles. 3 ~ Therefore they also follow
the 11-year solar cycle.
17. The sun also acts as a powerful source of cosmic
radiation during prominent flares. The spectrum of protons produced by these flares is much more enhanced in
the low energy portion than that for the primary cosmic
radiation 32 and in most cases moderate amounts ofshielding will be effective. The largest flares, for example
the giant flares of 4 May 1960 and of 23 February 1956,
may, however, produce dose-rates which are quite highat altitudes of the order of 10-20 Ian and their effect isconsiderable even at sea level. Calculations for the February 1956 increase show 35 that the integrated exposure
over the duration of the increase was 5 to 10 rad at analtitude of 15 Ian. Sola; particles produce a strong influx
at high latitudes of protons having energies from a few
tens to many hundreds of MeV. As these protons continue to bombard the earth's atmosphere for days they
may represent a major radiation problem in the stratosphere especially as they may produce dose-rates of theorder of 10 remjhr at 20-25 km altitude. 36 During yearsof high solar activity a dozen or more such events may
occur per year.

18. The neutron intensity would also be expected to
exhibit a dependence on solar activity corresponding to
the solar modification of primary cosmic radiation.
Short-term variations at high altitudes and latitudes andassociated with periods of high sunspot activity havealso been observed. For instance, Simpson27 reports increases in intensity of at least 30 per cent at 9 km altitude which persist for the order of days. Further variation in the neutron component will also occur near theearth's surface due to alterations in the moisture conterltof the soil, and it is also affected by the moisture content
of dense cloud formations. 57

II. Natural radio-activity in the earth's crust
NATURALLY OCCURRING RADIO-ACTIVE NUCLIDES

19. Naturally occurring radio-active materials arewidely distributed throughout the earth's crust and theresulting gamma ray dose to mankind varies from avalue somewhat less than that due to cosmic rays tovalues many times higher. Some of the more importantof these nuclides are the long-lived U 238 , Th 232 andRa 226 (and their shorter-lived daughter products). K~ 0
and the cosmic ray produced isotopes cu and H 3. Other
isotopes such as Rb 87 , La138 , Sm1 H and Lu176 also exist
in nature but their abundance is so low as to make anegligible contribution to the dose received by mankind.
The physical characteristics of some of these isotopes are
given in table II.
CONCENTRATION IN COMMOK ROCKS

20. In general, natural radio-nuclides are found to be
more concentrated in granitic rocks than in basaltic
rocks. 38 • 39 Limestones and sandstones are low in radioactivity, but certain shales are more radio-active, especially those containing organic matter. 40 Marine sediments appear to be more radio-active than either nonmarine or estuarian deposits. 38
URANIUM AND THORIUM. 21. Ura~ium ore has been found in large quantities
m Australia, Canada, Czechoslovakia, Republic of theCongo (Leopoldville), South Africa, the United States,

210

the Soviet Union and other areas. Large deposits ofmonazite, the principal thorium-bearing mineral, arefound in Brazil, the United Arab Republic, China, India
and the United States. Although thorium is more abundant than uranium, uranium is found in a much greater
variety of chemical combinations. Table III shows theirconcentration in various rocks, as determined by a number of workers, expressed as µ.µ.c/g.
R.AnruM-226

22. Ra is one of the daughter products of U 238 but,because of leaching and weathering, it is not necessarily
in equilibrium in soil with its long-lived parent. Thereis a considerable range of concentration in various rocks,
as indicated by table III. Particularly high concentrations
are found in alum shales in Sweden.n• 42 The Ra226 concentration in the soil in various parts of the United Stateshas been found by measurement to vary between 0.09
and 0.8 µ.µ.c/g soil. 26
226

POTASSIUM

23. Potassium is relatively abundant in nature. Its
radio-active isotope K 40 constitutes 0.0118 per cen~ 3 ofthe total amount of potassium and contributesH 28 ,8-dps
per g Kand 3.45 y-dps per g K. The K• 0 content of various rocks is given in table III. It has been estimated thatthe potassium content of soil is about 10-3 to 3 X 10-2 g
K/g soil 45 (1 to 30 µ.µ.cK. 40/g soil.)
RN 222 AND RN 220 IN THE EARTH'S CRUST

24. Since uranium and thorium are almost universally distributed, their respective short-lived gaseous
daughter products, Rn 222 and Rn220 , accumulate in soil
and rocks. The daughter products of this trapped Rn222
and Rn 220 contribute over half the observed gamma
activity of uranium minerals. 41 The Rn2 ~ 2 and Rn 220 in
the soil diffuse into the air at a quite variable rate, depending on a number of factors including moisture content of the ground, 46 presence of snow/ 7 amount of rainfall,48•49 conditions in soil and atmosphere, particularly
atmospheric turbulence and pressure.
DosE-RATES FROM THE EARTH'S CRUST

25. The gamma dose-rates in air over radio-active
rocks and soils can be calculated from the energies,
absorption factors and relative abundances of the various component gamma rays, allowance being made forscattered radiation. The expressions obtained by Hultqvist'2 and O'Brien et al. 50 for the gamma dose-rates in
air above ground containing uniform concentrations of
U 258 , Th 232 and K• 0 agree to within 10 per cent. The
average of their expressions gives the following relations
bet\veen the dose-rate in air (D, mrad/y) at a height ofone metre above ground containing uniform concentrations (S, µ.µ.c/g) of U 238 , Th232 (both in equilibrium with
their daughters) and K• 0 :
Du = 17.8 X Su }(1)
DTh = 25.5 x Srh
DK = 1.56 x SK
26. The ,B-particle emission of these naturally-occurring radio-nuclides can contribute an external dose to
the human skin. These skin dose-rates have been calculated by O'Brien et al.~ 0 for ,8-emission from U 238 , Th 232
and K• 0 in soil assuming homogenous distribution andcomplete equilibrium between the U 238 and Th232 andtheir decay products. The external contribution to thedose-rate deliYered to susceptible organs (such asgonads, bone, etc.) resulting from ,B-emission, must be
regarded as negligible.
27. Typical estimates of the average dose-rates in air
at a height of one metre above limestone may be of theorder of 20 mrad/y and that for granite areas may beof the order of 150 mrad/y. It is obvious, however, that
there will be quite large variations in these values, andthis is borne out by the measured terrestrial dose-rates
in air reported for areas in various countries as given
in table IV. Further, much higher values are reported
for some areas, e.g., monazite sands, where the uranium
and thorium contents are very high (see section VII
below).
28. The terrestrial gamma dose-rate inside buildings
will, generally, be different from the value out of doors
owing to the different radio-active content of the building materials and also the attenuation effect of the walls
for the radiation from sources outside the building.
A further small increase in dose-rate may be producedby the accumulation of Rnm and Rn 220 as a result ofpoor ventilation in the buildings (see section IV below).
Reported terrestrial dose-rates in air inside buildings invarious countries are given in table V.
29. In order to obtain tissue dose-rates to specificorgans due to e..xtemal gamma sources, allowance must
be made for attenuation by intervening portions of the
body. O'Brien et az.~ 0 have calculated the dose-rates in
man at various depths as fractions of the free-air gamma
dose-rates. Assuming that the testicles, ovaries andbone-marrow are at depthsn of 1, 7 and 4 cm, the resulting screening factors are 0.68, 0.58 and 0.62, respectively. These are in very good agreement with theaverage experimentally determined screening factors obtained by Spiers52 using a water-filled model-0.70, 0.56
and 0.64 respectively. It is, therefore, suggested that avalue of 0.6 be used as the screening factor for gonads
and bone-marrow in the case of terrestrial radiation.
(F III, 18)
30. The estimation of mean dose-rate to a population
should be made by a carefully planned series of measurements of dose-rates both indoors and out of doors andthen weighting the measurements according to time spentin each place. A very good example of such a survey is
one which was recently made in four areas in the Umted
Kingdom. ~ 3 The mean values of local gamma-radiation
dose-rates obtained are given in table VI. In computing
the mean dose-rates to the gonads and bone marrow,screening factors of 0.63 and 0.64 respectively were used
and it was assumed than an average of six hours per
day per person was spent out of doors.
31. Insufficient measurements have been made to enable a reliable estimate of the mean dose-rate to the world
population to be made. It should be pointed out that the
major part of most people's lives in most areas of theworld is spent inside buildings. With this in mind, consideration of tables IV and V seems to indicate that,except for certain regions of high activity, the averageterrestrial gamma dose-rate in air is of the order of
80 mrad/y, i.e., a mean gonad and bone dose-rate to theworld population from terrestrial gamma radiation is
only about 50 mrad/y (para. 29).

36. The skeletal content of Ra228 is determined by its
introduction into the body through food, water and, toa lesser extent, air. Muth et al. 62 have shown that undernormal environmental conditions only about 10 per centof the Ra 226 enters the human body through water andabout 90 per cent from food. \Vhen the Ra 220 concentration in water is relatively high and the intake fromwater exceeds the intake from food, some correlationi; found to exist between the skeletal concentration andt.l1e concentration in water. 54 With relatively low (normal) Ra 226 concentrations in water, no such correlation
is observed as the skeletal Ra226 content is then basicallydetermined by its intake from food.

Ill. Natural radio-activity in water

IV. Natural radio-activity in the lower atmosphere

32. An e..xtremely wide range of natural radio-activities exists in various types of water, depending largely
upon their origin. The levels of natural activity originat-

RN 222 AND RN 220 AND THEIR DECAY PRODUCTS

ing from uranium and thorium series are found to behigh in certain natural springs which are found in areas
where there are high concentrations of uranium andthorium in the soil. Similarly. drinking water e.xhibits
wide variations of activity depending upon its origin
and on the treatment it receives before it becomes available for consumption. High levels of natural potassium40 activities are found in sea-water.
PUBLIC WATER SUPPLIES

33. Public water supplies are of interest since drinking water is one of the modes of entrance of naturalradio-activity into the body. Table VII gives concentrations of Ra 226 and Rnm present in various public watersupplies. It should be pointed out that the radium content of water is reduced by the introduction of filtration
and/or softener systems, so that the intake of radiumfrom a particular supply may be modified in the caseof some individuals by the use of domestic water softeners. Lucas 54 quotes a case where one of these units(ion-e.xchange type) removed 98 per cent of the Ra226
present in the normal water supply.
34. :Many drinking water supplies will also containnaturally occurring Th 232 and/or its decay products.
Krause 55 has investigated the Ra228 content of twentysix samples of well-water from the Illinois (UnitedStates) sandstone area and has compared them with the
Ra 226 contents of the same samples which had been previously measured by Lucas. 56 The Ra 228/Ra2 ~ 5 ratio covered an e.xtremely wide range of values, 0.04 to 2.43,
with an average of 0.60. The Ra228 concentrations ranged
from 0.9 to 7.9 µ.µ.cjl, whilst Ra 226 went from 3 to36 µ.µ.cjl.
OCEAN WATER, RIVERS AND NATURAL SPRINGS

35. Typical concentration of U 238 , Th 232 , Ra220 and40
K. in sea-water are respectively 0.2-9 µ.µ.c/l, 57 0.11.10-3 µ.µ.cjl,~ 8 0.02--0.3 µ.µ.c/1 59 and 300 µ.iicjl. 60 Table
VIII gives the concentrations of U 238 , Ra226 and Rn:!!! 2present in various natural waters and springs. Springwaters may exhibit extremely high radio-active concentrations, particularly of Rn 222 , but as they are consumed
regularly only by a very small percentage of populations,and since Rn 222 ingested from drinking water probably
has a mean life of about one hour in the body, 01 the remlting mean dose to the world population from springwater is negligible.
SKELETAL RA226 CONTENT DUE TO DRINKING WATER

37. Wherever there are uranium or thorium bearing
minerals present in the soil, the gaseous decay products211

Rn 222 and Rn220 are injected into the atmosphere by diffusion (para. 24). The rate of injection varies considerably with seasonal and meteorological conditions. Measurements of Rn 222 and Rn 220 and/or their daughter
product activities is often carried out by a combinationof filtration and ionization chamber or scintillation methods.63 The daughter products, in the form of ionizedatoms, attach themselves to the aerosols and dust particles which are always present in the air. The collection
efficiency of filter papers for these particles is often very
uncertain and depends on the linear air velocity throughthe paper and the size range of the dust particles in the
air. 6 ~• 65 Thus, in low dust atmospheres such as those of
air-conditioned rooms, the retention of the daughter
products by filter papers may be very low. Ion collection efficiency may, however, approach 100 per cent by
the application of a suitable electric field. 60 In addition,
the Rn222 and Rn 220 present in the atmosphere are notnecessarily in equilibrium with their daughter products
and will also contain varying fractions of uncombined
atoms of daughter products, both of which affect thedose-rate to the lungs upon inhalation (para. 42). The
concentration of Rn 222 and Rn 220 will also vary withheight, for instance the average value at a height of
10 m for Rn 222 is 90 per cent of that at groundlevel. 25 • 67 • 88 Rn220 , by virtue of its very short half-life,
will virtually have disappeared at heights of 10-20 m.
The average concentrations of Rn 222 and Rn 2 " 0 present
in free air at ground level in various regions are given
in table IX. Values are particularly dependent upon thelength of time the air mass spends over continental landmasses. 67 • 69 • '° Also, in areas of high radio-activity andunder special meteorological conditions, e.g. smog andtemperature inversion, values may be higher by several
factors of ten.
38. As the majority of the people spend a large partof their time in buildings, the average natural radioactivity concentration in air which refers to the world
population is more dependent upon the level in buildings
than in free air. In general, the level indoors is higher
than that out of doors and it is dependent upon thebuilding construction materials and the ventilation conditions. The level out of doors will determine the concentration that will be reached by very efficient ventilation of the building. The results of measurement by
Hultqvist' 2 in three types of buildings in Sweden for
conditions with and without ventilation are given intable X. A ventilation rate of 1()-8/sec was used, i.e., theair in the building was renewed every seventeen minutes.
39. Reported Rn 222 content of the air indoors at various localities is given in table XL Consideration of thesedata indicates that the best estimate of a "world average"
concentration of Rn 222 in air may be of the order of 0.5µ.µ.c/l. The corresponding figure for Rn 220 may be of theorder of 0.02 µ.µ.cjl.
40. The external gamma dose-rate in air (D) produced by a concentration of C µ.µ.c/1 of Rn 222 or Rn 220 inequilibrium with their decay products per litre of air canbe calculated by Hultqvist's relation :42
D = 14C mrad/y
In obtaining the dose to various body organs allowance
must be made for body shielding. The screening factorof 0.6 used previously for terrestrial radiation (para. 29)
will again be used here. Hence, for "average" air concentrations of Rn 222 and Rn 220 (para. 39), the total bodytissue dose-rate will be of the order of _1.5 !11rem/y.
It should be pointed out, however. that this contribution
to the tissue dose-rates will have been included in any

measurement of local gamma-radiation dose-rates thathave been made and so is allowed for in the average local
gamma dose-rate given in paragraph 31.
41. There will also be a further total body tissue dose
produced by the Rn 222 and Rn 220 in the air resulting
from that portion which is transferred via the bloodfrom contact with the alveolar air. Using Spiers53 results,
the total dose-rate to soft tissues due to the inhalation of
air containing 0.5 µ.p.c/I of Rn 222 in equilibrium with its
daughter products, is of the order of 3 mrem per year.
Ruzer's results 71 indicate that the whole body dose-rate
due to the inhalation of 0.5 µ.p.cjl of Rn 222 is of the orderof 0.01 mrem per year.
42. The dose-rate to the lungs from Rn 222 and Rn220
and their decay products occurs as a result of deposition
and/or passage back and forth through the tracheobronchial tree of these decay products72 and depends
largely on their size, specific activity and percentage of
uncombined atoms, 73 since these determine the amount ofradio-activity retained in the lungs. Rn222 and Rn220 ,being gases, are retained only to a very small extent.
and so do not make a very large contributon to the doserate. Stannardu gives the mass deposition of small particles in the respiratory tract (figure 2), derived fromthe results given by Hultqvist.'2 Values for dose-rates
to the lung for e.xposure to Rn 222 or Rn 220 in equilibrium
have been calculated by various workers. For instance,
using the expressions of Hultqvist,42 Morgan,' 2 Ruzer, 71
Shapiro,75 and Schraub,76 values are obtained of 20 mrad(200 mrem), 90 mrad (900 mrem), 10 mrad (100mrem), 10 mrad (100 mrem), 250 mrem. respectively,
for the annual dose to the lungs from a continuous concentration of 0.5 µ.µ.cjl Rn222 in equilibrium. The variations in these estimates are chiefly due to the differencesin the assumption regarding time spent in the relevant
locale. respiration velocity and the weight of the irradiated lung tissue. Hultqvist4 2 has estimated the dose-rate
100

90

80

70

-:

"
~60

\

.,,
~

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.,,
"
~"' 40D

Lower
respiratory
tract only

.."

0

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30

zo
10

0
0.05

.0.1

0.2

o.s
1.0
Particle •lze - microns

2.0

Figure 2. Percentage mass deposition of small particles in the
respiratory tract212

to the lungs from Rn 222 and its decay products and from
Rnm and its decay products in the case of radio-active
equilibrium and also where this equilibrium has been
greatly disturbed by a high ventilation rate ( lQ-3/sec.).
The dose-rates to the lungs along with the average concentrations of Rn 222 and Rn 220 in air for three types ofbuildings in Sweden are given in table X. It is apparent
that the lungs receive a higher irradiation from natural
sources than any other body tissue.
PB" 10, B1 21 o•n AND Po 210
43. The daughter products, Po 218 , Pbm, Bi214 andPom, because of their short half-lives, are normally notvery far from secular equilibrium with the parent Rn222 ,but the concentrations of Pb 210 , Bi 210 m and Po 210 will be
relatively much lower at ground level than their equilibrium values, as they will be washed out of the atmosphere long before equilibrium has been reached. Measured levels of Pb2 1.0, Bi210 m and Po210 in the air at groundlevel are given in table XII. These concentrations are
insignificant with respect to dose considerations.

in nat~re .. Thus, for example, the C13/C12 ratio in plant
matenal is 1.7 per cent less than that in the atmosphere78' 79 and the change for the C14/C12 ratio is twice
this amount. 80 • 81
·Production of natural C1 4

47 .. The_C 14 p~oduccd in the atmosphere owing to absorption ot cosmic ray neutrons may be estimated fromflux-energy data and the neutron cross-sections of thevarious constituents of the atmosphere. These cosmic
ray neutrons are entirely secondary in nature.

18·

The neutrons are slowed down by collision and all
ultimately undergo neutron capture by nuclei present in
the atmosphere. It is generally assumed that virtually allof the cosmic ray neutrons result in C14 production,8 2i.e., the NH (n,p) C14 is the only reaction of importance.
However, Hess et al. 83 conclude that only 67 per cent ofcosmic ray neutrons are captured by this process, 16 percent are captured by other processes, 17 per cent leakout of the atmosphere, and 0.2 per cent are captured by·
the earth.
49. The short-term variation of cosmic ray neutron
flux with time. altitude and latitude is considerable(paras. 7,_11,_J~,_ 14, 18), making it quite difficult toobtain an average value for neutron production to be
used for the estimation of C14 production. The computation of the cosmic ray C1' production rate has been
carried out by several workers 82 - 88 who have obtained
values ranging from 1.3 to 3.1 atoms/cm2 /sec. (i.e., average 2.2 atoms/cm 2/sec which is equivalent to 3.4 X 1026
atoms cu/y/earth's surface).

CARBON-14*

44. Carbon is one of the elements that are essential to
all forms of life and thus is involved in most biologicaland geochemical processes on the earth. Associated withthe stable isotopes of carbon ( C12 and about 1.1 per centCP), there is always a very small but variable amount of
C14 , a pure ,8-emitting (E max = 0.165 MeV) radioactive isotope of carbon with a half-life of 5760 ~ SO
years. 71
45. C14 is formed upon absorption of neutrons in thenitrogen nuclei of the atmosphere. When the neutrons
involved are of cosmic ray origin, the CH formed isreferred to as ''natural", and when the neutrons originate from nuclear testing, the resulting C14 is "artificial".

50. If the average value of the cosmic ray flux. has
been constant over the last tens of thousands of years(several C14 half-lives), the c1-1 activities in the carbon
cycle would be in a "steady state" situation, for production of cu would be balanced by decay of ci~. The specific activity of CH would then be given by the following
relation:

46. Due to isotopic fractionation in most processes inwhich carbon is involved, small variations occur in therelative amounts of the three isotopes of carbon foundSpecific activity of CH(disintegrations/min/g carbon)_Production rate of CH (atoms/cm 2/min)-Carbon in exchangeable carbon cycle (g/cm 2 )2.2 x 60=
_ dpm/g,..., 16 dpm/g
81

51. Experimental determinations of the specific activity of natural C14 in the biosphere have ranged from
12.9 to 15.3 dpm/g carbon, 81)-93 the most recent measurement being 14.46 dpm/g. 89 The absolute disintegration
rate for C1 4 in pre-1900 biospheric carbon . tnay thus betaken to be 14-+- /dpm/g, which corresponds to a C14/C12
ratio of 1.20 X 10-12 •53. All these data support the basic premise that the
average cosmic ray flux has been essentially constant for
hundreds of millions of years, and that any variation over
the time period of interest for natural C14 ( 100-50,000
years) is less than a few per cent. It has been pointed out
by Stuiveru 9 that available evidence on sunspot activity(which is known to affect the cosmic ray level in theupper atmosphere) suggests some correspondence between sunspot activity and the CH concentration in theatmosphere, as indicated by tree ring measurements.95 •1®
Recent measurements of C14 variations in an 800 year
old Kauri tree show 101 a gradual increase in the C14 content of the atmosphere over the last 850 years which
could be attributed to an increase in the cosmic ray flux.
54. This natural CH in the biosphere results in a negligible e.xtemal dose-rate to man, and a larger, but stillquite small, dose-rate due to its presence in the bodytissues (para. 82).

52. The constancy of the cosmic ray flux with tim~ isof considerable interest, and three independent types ofexperiments have been carried out to give further information on this question. These three methods, which
cover different time periods, are:(a) Measurement of the C14 activity in biosphericsamples of known age (time range of several thousandsof years).s2,9f-96( b) Comparison of radio-carbon and ionium ages ofocean sediments (time range of a few thousands to tensof thousands of years). 9 '( c) Comparison of observed activities of various cosmic ray induced radio-isotopes in meteorites (time rangeof hundreds to millions of years) .98

TRITIU:II

55. Tritium, H • a radio-active isotope of hydrogenwith a half-life of 12.26 years, is, like C1 4, _continuously
beingyroduced in the atmosphere by cosmic rays, thus
3*For discussion on 0 4 see also annex F, part I.

213

giving rise to concentrations of tritium in nature. Thesenatural tritium levels have, since 1952, been modified by
the addition of tritium to the atmosphere by nuclear
weapons tests, especially by high yield fusion devices.
56. The tritium content of molecular hydrogen in the
troposphere of the middle latitude regions of the northern hemisphere in 1949-1951,1°2 1954-195610 ! and mid1959103 respectively was about 30, 300 and 1500 µµc/g H.
The resulting tissue dose-rate due to the incorporationof tritium in the body is considered in paragraph 84.
BERYLLIUM-7 AND OTHER COSMIC RAY-PRODUCEDNUCLIDES

57. Other radio-active nuclides known to exist naturally owing to the interaction of cosmic ray neutrons·with the atmosphere include Be7 , Na22 , P 32 and sis.
Of these, Be 7 , with a concentration of the order of2 X 10- 5 µ,uc/litre, 104 •105 has the highest concentration.
The tissue dose contribution from each of these nuclides
is negligible.
V. Natural radio-activity in foodstuffs

58. The natural radio-activity in soil and water becomes transferred to man via the food-chain cycle. Studyof this aspect requires measurement of activity levels inplants, some of which are used directly as human foods,
while others, such as grasses, form the principal foodof animals which in turn themselves become humanfood (F II). There is a wide range of activities in vegetation and there appears to be no simple correlation withthe corresponding activities in soil for which the range issmaller. As there is not much information regarding thediscrimination factors for the soil-food and food-man
processes, the dose-rates to particular body organs are
best related to measured concentrations in the particularorgans.
TOTAL ALPHA ACTIVITY

59. A number of measurements have been reportedof total a-activity in various dietary materials, but as thevarious daughter products in both the U 288 and Th 282
radio-active series may exist in different degrees of nonequilibrium, the individual isotopes should be identified
in order to obtain the maximum information.
60. An extensive set of data on the total a-activity offoods has been published by Turner et al.,1 00 and values
vary from less than 1 up to 1.7 X 10' ,uµc/kg of food.
In general, their measurements show low activities inmilk products, fruit and vegetables, but higher values incereals and nuts. They estimate that an adequate dietwill not contain less than 2 µµ.c total a-activity per day,but it is obvious from the large range of values ofactivity in the different ioods that small changes in eating
habits can result in a large change in the intake of radioactivity. Mayneord107 estimates that an adequate Western
diet is not likely to contain less than S JLJLC of a-activity
per day.
RADIUM-226
61. Regular three-monthly measurements108 of theRa226 content of the various foods in the average diet ofthree areas in the United States are being carried out
by the Atomic Ener~ Commission's Health and Safety
Laboratory and their results are given in table XIII.
By using the Department of Agriculture's food con-sumption figures for the United States, Hallden and
Fisenne 108 conclude that the average daily intake of Ra 226
for the two surveys in New York City, Chicago and
San Francisco is 2.4, 1.9 and 1.7 µµc respectively. Measurements of the Ra 226 in the diet of infants in New York
City109 indicate that if the August 1960 samples are
typical, then the intake of infants during the first yearof their life is 212 µ.µ.c (0.6 µµc/d) of which about onethird comes from milk and one-half from cer~s.
62. Muth et al. 62 have reported the Ra 226 content of awide variety of foods in Germany which give a rangeof activities 0.1 to 6 µµcjkg. Their values, some of which
are given in table XIV, agree very well with the UnitedStates figures in table XIII. Muth et al. estimate that thedaily intake of Ram is about 3 µµc, of which about 10
per cent is contributed through intake of Ra226 in water.
63. In addition to total a-activities for different foods,
Turner et al. 106 reported the Ram activities for a few ofthe same samples. Some of these values are given intable XV for purposes of comparison with the UnitedStates and German results. It is thought110 that the highvalues for cereals might be due to a contribution from
Australian wheat for which total a-activity content has
been reported for some samples to be higher than thatfor wheat from the United Kingdom and Canada.m
THORIUM

64. No evidence has yet been found of the presenceof Th232 in dietary materials. Mayneord and Hillm havepublished the a-spectrum of a sample of breakfast cereal
made from whole wheat. This shows the two long-lived
a-emitters, Ra 226 and Th 228 and their daughters. U 238
and Th 232 are absent and the Th 228 may therefore be
presumed to originate from Ra228 (a ,8-emitter which
therefore does not appear in the spectrum) rather thanby metabolic uptake of the element thorium. Later evidence113 on the a-activities of leaf ash indicates uptake ofRa 228 in preference to thorium. Turner et al. 106 reported
both Ra226 and Th 228 contents for twenty-three different
food samples, and the average Th 228jRa226 activity ratio
for these was 0.9.
PB210, BI21om AND Po210
65. It has been observed112 • 113 that the a-activity observed in certain samples of grass is mainly due to thepresence of Po 210 , accompanied by its parent Pb 210 (,8-yemitter). Hill114 suggests that this largely originatesfrom a process in which Pb 210 , resulting from the decayof atmospheric Rn 222 , together with a fraction of theequilibrium amount of its descendant Po 210 are depositedby rainfall directly on to the foliage. This fractionation isprobably explained by the fact that both nuclides arise
from the decay of a gaseous precursor. It is evident that
Po210 or one of its precursors, such as Rn 222 or Pb 210 . may
also be taken up directly from the soil. Since snow andeven moderate rainfall can restrict the rate of escape ofRn 222 from the surface of the soil (para. 24 above), it isclear that these factors could result in concentration of
Pb 210 , and in tum Po 210 , being produced in the top layer.
The relative uptal<:e by vegetation from the soil and fromdirect deposition on the foliage probably varies from site
to site, depending on parameters such as species of plant,
soil drainage characteristics, depth of water table below
the surface, etc.
POTASSIUM-40

66. K 40 is present in a fixed proportion (0.0118 percent) of total potassium in all natural materials. The
214

potassium content of food varies considerably-for example in the United Kingdom115 values given for a verylarge ~umber of samples of different types of food range
from 0.1 per cent up to about S per cent (0.76 µ.µ.c
K• 0/g up to about 38 µ.µ.c K.o/g). Co~sequently potassium intake will be very dependent on diet and may show
large variations between countries. For instance, Scott
Russel1 116 has pointed out that in the United Kingdom
23 per cent of the tot;;J potassium in diet originates .fro~
dairy produce and 3;, per cent from pot~toes, while m
the United States the figures have been gwen as 38 percent and 19 per cent respectively. The potassium intake
for the United States based on per capita food consumption has been calculated to be approximately 2300µ.µ.c/d.111, us

cent of the a-emitting radio-active material is in the soft
tissues. 107
RAnIUM-226

VI. Natural radio-acthity in the human body

70. Ram is taken into the body through food, water
and, to a lesser e.-.;tent, air (para. 36). The total Ra 226
content of normal human bodies has been determined bya number of workers, and values ranging from 3-1400µ.µ.c obtained. These results are summarized in table XVI,
along with data regarding the number of samples measured, and the average Ra 326 content of dri?king waterin the area from which the samples were obtained. Where
results are reported in terms of activity per gram ash,and individual total ash values are not given, it is assumed that a 70 kg man produces 2600 g skeletal ash and
400 g tissue ash. The results. show5 ' some co~relation
with the Ra 226 content of drinking water when thts source
is predominant.

67. The e."'(tremely low levels of naturally occurring
radio-activity normally present in the human body makemeasurement of the individual radio-isotopes very difficult. In vivo, measurement of gamma rays is often used
to measure the body potassium content. The total bodyRa 226 content can be estimated by measuring the rate ofexhalation of radon and assuming a general value forthe fraction of the total radon formed which escapes inthe breath. This fraction is not accurately known andmay indeed vary under different conditions. Ra226 andother nuclides can also be estimated by the analyses of
autopsy samples.

71. Wal ton et a/. 121 measured the Ra228 concentrations
in samples from up to 11 bones from each of 11 bodies
in order to determine the variation within the skeleton.
They concluded that there is no systematic difference inthe radium content of the various bones of the averageskeleton at least to within -+- 15 per cent. Departuresfrom th~ mean of up to SO per cent do occur in a few
specimens. However, this degree of consistency within
the various bones was not confirmed by Holtzmanu 2 inhis measurements of both the Ram and Pb 210 content
of five bones from each of three persons who had beenborn in different states in the United States. These result? are given in table XVI!.

TOTAL ALPHA-ACTIVITY

68. Turner et al. 119 measured the total a-activity ofbones of persons native to Cornwall, London and Cumberland. The average value is 0.38 µ.µ.c/g ash, but individual results show large variations (figure 3). Thereappears to be a significant difference between values forCornish bones and those from the London area or from
Cumberland. The total a-activity in 10 Eskimo bones 107
showed a range from 0.18-0.97 µ.µ.c/g ash with an average of 0.61, and the rib of an Egyptian107 who died almost
4,000 years ago gave a value of 0.34 P.J!'C/g ash. Figure 3
indicates that for persons not occupationally e.-.;posed toa-activity, the concentration does not vary with age, but
as the weight of the skeleton increases from birth toadult so the total a-activity in the skeleton increases inthis period and then stays constant.

'! 1.0

•

s
.a

.

1"I

8. ..

~

o.s

•

•

:f)
i:

•

•

0

x ox~ o •
~ 8x
Xx

I
"l$'

~

•
•
• • ~•• ••

x

0
lfl

·:o

30

4JJ

50

60

70

•

80

90

100

72. There is a distinct possibility that measurementson teeth may be used as an indicator of Ra 228 bone levels,
particularly if water concentrations are constant in thearea. Lucas 64 found a value of 0.10 µ.µ.c/g ash for the
average of Ra 226 levels in teeth for nine persons which
was almost identical to the 0.11 µ.µ.c/g ash found for bonefrom residents from the same city. The total a-activity
levels in teeth obtained from the Royal Dental Hospitalwere also very similar to those in bones from persons
who had lived in London. 107 Further, the activity of teeth
from the inhabitants of Niue Island, 123 an area of highnatural radiation (see section VII below), is of the orderof ten times that of teeth from the inhabitants of normal
areas.
73. The relative concentrations of radium in the skeleton and body tissues is uncertain. Muth et al. 62 suggestthat 25 per cent of the total body radium is contained in
the skeleton whereas Hursh et al.m give a figure of 78
per cent and LucasG• 80-85 per cent. Results given by
Hi11110 also tend to support this higher figure. The results for bone and muscle ash and wet tissue are given
in table XVIII. No explanation has been given for the
relatively high tissue values obtained by Muth, but total
a-activity values in bone and soft tissue (para. 69)
favour a skeletal content of about 80 per cent of the total
body value.

74. Consideration of the above information indicatesthat the world average for the Ra226 total body burden is
likely to be closer to 50 µ.µ.c than 100 µ.µ.c. In subsequentconsiderations, we will assume a conservative value of
75 µ.µ.c, of which 80 per cent ( 60 µ.µ.c) is in the skeleton.

·Age (years)

Figure 3. Human bone ash, total a activity. e. Cornwall;
X, London; 0. Cumberland

69. Mayneord120 finds a large variation of activity for
different soft tissues. 0.15 to 1.00 µ.µ.c/g ash, but the
average value of 0.52 µ.µ.c/g ash agrees very well withthat obtained for skeleton ash. This leads Mayneord toconclude that in the normal human being, about 25 per

THORIU:M

75. The presence of Th 228 in human tissues125 has been
demonstrated by means of a-ray spectroscopy, but, as215

with plant tissues (para. 64), the parent isotope of thethorium series, Th 232 , has not yet been detected. It istherefore thought 12 ~ that the Th 228 originates from themetabolic uptake of radium in the form of Ra228 rather
than uptake of thorium. Because the half-life of Ram
is considerably less than that of Ra226 , it may be expectedthat the Ra 228/Ra226 activity ratio will be a maximum in
newly fomed bone and will be less than this value inolder bone. The magnitude of this effect is not known
and, indeed, it does not appear to be sufficient to introduce an age effect into the total a-activity content ofbones (figure 3). Mayneord et al. 125 suggest that 40 per
cent of the total a-activity in adult bone is due to radiothorium, i.e., Th 228jRa226 series activity ratio is approximately 0.7. Measurements reported by Stehney128 onashed bone samples from six subjects (average Ra226
skeletal content of about 90 µ.µ.c) gave an average
Th 228jRa226 series activity ratio of 0.4. This value israther uncertain owing to the large fractional errors in
the Th 228 measurements. Using thoron in breath technique, Cullen121 has found indications of much higher
Th 228 content of normal persons. It will be assumed thatthe world average Ra228 total body content is 50 µ.µ.c, of
which 40 µ.µ.c is in the skeleton.

the bone. The results for the average Ra 226 and Ra228
contents, suggested in paragraph 77 and assuming 35 percent and 100 per cent equilibrium respectively, are given
in table XIX. Also included in the table are the estimateddose-rates to the same tissues resulting from a skeletal
Pb 210 content of 200 J.Lp.C ( 50 per cent equilibrium). The
average dose-rates to the body tissues other than bone,
assuming that the Ra 226 , Ra228 and Pb 210 activity is uniformly distributed and that the activity levels are 25 percent of the values assumed for the skeleton of an average
individual, are about 0.5, 0.8 and 0.3 mrem/y respectively from each of the above radio-isotopes. 130
POTASSIUM -40

79. In viva measurements of total body potassium
content have been made by a number of workers. The
results of measurements by Anderson et al.1 31 for L590
males and females as a function of age of the subject are
given in figure 4. The concentrations vary considerablywith age, and above an age of twelve years, a sex difference appears. Beyond twenty years of age, the percentage
content in both males and females decreases in a similarmanner but the male level is about 20 per cent higher
than the female.

Pnz10, B121om AND Po210
76. Various workers have determined Pb 210 , Bimmand Po210 concentrations in human bone in excess of that
expected from the Ra226 content. Holtzman122 mademeasurements on samples of individual bones fromforty-four humans and found an average skeletal Pb210
content of 360 µ.µ.c (corresponding mean Ra!?26 content
was 100 µ.µ.c).He concluded that the origin of this Pb 210
was mainly from food, to a slightly smaller e.."{tent fromthe atmosphere and a minor contribution only fromdrinking water. Hursh128 obtained a value of 105 µ.µc
for the mean skeletal Pb 210 content of eighteen cadavers
obtained in the New York area (average Ra 220 content
was 120 JLP.C). Hill and Jaworowski129 measured thePb 210 content of bone samples from six subjects andfound an average skeletal content of 160 µ.µ.c. It will beassumed that 200µ.J.LC Pb210 is the skeletal content of an
average person.
DOSE-RATES FOR NATURALLY OCCURRINGU AND TH SERIES

77. From the available data on natural radio-activity
in humans, the average skeletal content of Ra 226 , Ra228
and Pb 210, each in various states of equilibrium with its
daughter products, has been chosen as 60 p.J.LC, 40 p.J.LC and200 µ.µ.c respectively (paras. 74-76). The range of values
for individuals is extremely large, e.g. for Ra226 it may
be higher or lower than the average value by a factor
of at least 25 (table XVI). However, for a population
in a given small area, the range is likely to be muchsmaller.
78. The dose-rate to bone due to the naturally occurring uranium and thorium series is mainly due to thealpha-emitting components, and hence the irradiation
pattern is extremely variable and depends on the size ofthe particular tissues being considered, their relation to
the radio-actiYe deposit and the ranges of the alpha particles. Spiers130 has calculated the dose-rates to the osteocytes, the connective tissue lining the walls of the Haversian canal and the bone marrow originating from theRa 226 and Ra 226 content of bone on the assumption that35 per cent of the Rn 222 and Rn220 formed is retained in

2.5

.i

..

~ 2.0 0
0

'::I

~
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~

~ 1.s

.

l!
0
p..

•

o Males• Females

1.0 L.L.L.&..&..L.L.L.JL.L.J!..l..lu...&..L...L.........................................'-'-'...............................
0

10

20

30

40
50
Age (years)

60

70

80

Figure 4. Average body potassium concentration of males andfemales as a function of age of subject

80. The potassium content of the various body organs
varies considerably from about 0.05 to about 0.31 per
cent, and the average for the whole body is about 0.2 per
cent. 132 There is evidence that the potassium content ofgonadal tissue is close to 020 per cent by weight, andusing this figure, Rundo133 estimates that the dose-rate
to the testes is 17 and 2 mrem per year from the /3- andy-radiation respectively. This is in good agreement withthe values of 16.5 and 2.3 mrem/y given in the 1958 report of the Committee and 18 and 2 mrem/y by Spiers. ~ 2
81. In trabecular bone, Spiers53 quotes the potassium
content as being between a value of 0.05 per cent formineral bone and a value near to 0.2 per cent for bonemarrow, and gives the mean dose-rate as 15 mrem peryear.
CARBON-14

82. The tissue dose rate due to natural C14 has been
given as 1.0 mrem/y, 52 1.5 mrem/y13 ' and 1.6mrem/y, 135
the difference between these values being essentially due
to the values assumed for the specific disintegration rate216

of natural CH and the average beta energy per C 14 disintegration. Taking 14 dpm/g carbon as the specific disintegration rate (para. 51), 50 keV as the average C1'beta energy136- 138 18 per cent1 as the average carbon content of the \vhole body of 70 kg weight, REE equal to 1,
then the average dose throughout the human body due
to natural cu is 1.06 mrem/y. The corresponding average dose-rate to soft tissue, with a carbon content of
12 per cent, 139 is 0.71 mrem/y, and to bone, with a carbon
content of 27.8 per cent, 139 is 1.64 mrem/y.
83. Owing to the Suess Effect (F I 68) the dose reduction during the period 1850-1954 was approximately
one mrem (about 0.01 mrem/y). If the use of fossil
fuels up to year 2000 is as has been estimated,1' 0 theSuess Effect will then be nearly 10 per cent and the dose
reduction over the period 1850-2000 would be approximately four mrem.
TRITIUM84. The natural level of tritium in water in the middle
latitude regions prior to the introduction of tritium due
to weapon testing was of the order of 0.005-0.02 µ.µ.c/g
H.Hl-'.l·u Assuming soft tissue to be 100 per cent water,
and that the average energy of tritium beta rays is 6 keV,
this implies an average dose-rate to soft tissue of about
0.003 mrem/y (REE= 1.7) or 0.006 mrem/y if an
REE of 3 is used (para. 3).6
VII. High natural radiation areas
85. In a small number of areas the dose-rate from natural background radiation is considerably higher thanthat experienced by populations in the major portion of
the world. This high radiation background is due to thepresence of larger than normal amounts of naturally
occurring radio-active materials in the soil, drinki~gwater, air, building materials, etc., and al~o to th.e cosmic
ray altitude effect {paras. 1_3 an~ 14). It 1s cons1der~145
that studies of the populations m these areas are hkely
to contribute to the fund of biological knowledge and theultimate specification of the genetic risks accruing fromincreasing exposure to ionizing radiation. This type ofstudy is one of the few ways of studying the effects ofionizing radiation on human hereditary material.

represent a continuous source of radiation exposure tolarge populations.
90. In those areas where the drinking water is ofhigher than normal activity, the populations are receiving
additional radiation exposure and may be of interest forstudy of possible biological effects. One such area wherea detailed survey is currently being made is in the Middle
vVest region of the United States. Some of the drinking
water in this area originates from wells which penetrate
the deep sandstone formations and the water has concentrations up to 37 µ.µ.c Ra 220Jl. Results reported so
farm indicate that drinking water containing more than
1 µ.µ.c Ra226/l is consumed by approximately 800,000
people, of whom about one half consume water containing more than 4 µµ.c Ra 226jl. Of these, about 30,000
people consume water with activity in the range 10-37µµ.c Ra226Jl. The resulting range of Ram skeletal burdensM in people who have been consuming this water forlong periods of time is given in table XVI.
HIGH NATURAL RADIO-ACTIVITY IN THE AIR

91. The Rn 222 and Rn 220 content of air will generally
be higher in areas of higher than normal natural radioactivity. For instance, the average Rn 222 concentration at
Bad Gastein, 148 which is situated in a deep valley containing many radio-active springs, is about 1 µ.µ.c/1 comparedwith the average value of about 0.1 µ.µ.c/l for the European continent. Also, concentrations in confined volumes
such as buildings will be considerably higher if ventilation is poor or absent. Under certain meteorological conditions, e.g., during fog, the natural radio-activity concentration in the air may increase by several factors often.
HIGH NATURAL RADIO-ACTIVITY IN BUILDI~GS

92. Aside from high radiation in buildings due to theincreased Rn 222 and Rn 220 content of the air (para. 91),
dose-rates may be increased owing to the high naturalradio-activity of the construction materials. Granite andlight-weight concrete containing alum shale are common
building materials which often result in particularly highradiation levels inside buildings, as can be seen from thedose-rates give in table V.
HIGH ALTITUDE AREAS

li:rGH NATURAL RADIO-ACTIVITY IN THE EARTH'S CRUST

93. As discussed in paragraphs 13 and 14, the cosmic
ray intensity increases markedly with altitude. This raises
the possibility of study of populations living at al~tudesof the order of 3,000 metres where the total cosnuc ray
dose-rate due to the neutron and ionizing components
may be of the order of 50-150 mrem/y. Table XXI gi"."essome of the high altitude areas in the world ~long with
their altitude, latitude, population us and cosmtc ~y contribution to tissue dose-rate estimated on the basis of the
figures given in table I.

86. There are five known major inhabited areas where
there is increased radiation from soil or rock-these arein Brazil, France, India, Niue Island and the United
Arab Republic. Data on the size, population and doserates of these areas are given in table XX.
87. The Kerala radiation measurements1 '° were madeinside three main types of houses in ten villages in thearea. The results did not show any clear relation between
radiation levels and structural differences in these houses.
The average gamma dose-rates in the .viJ!ages includedin the survey revealed a twenty-fold variation (131-2,814
mrad/y), and .the. average value of 1,_300 mrad/y. is
obtained by we1ghtmg values for each village according
to its population.
88. There also exists the possibility of an additionalsignificant radiation dos~ ~o the ~opula.tions ~n these ar~asdue to internal deposition ot radio-active material.
No published material on this aspect is available atpresent.
89. Certain natural springs have a very high naturalradio-activity content and some of these are listed intable VII. However, these springs are not generally used
as a permanent source of drinking water and so do not

VIII. Summary of exposure data
94. The mean gonad and skeletal dose-rates from natural sources of irradiation under "normal" conditions
are given in table XXII. (For information on highnatural radiation areas, reference should be made tosection VII above.) The suggested typical value for ~etotal cosmic radiation tissue dose-rate, 50 mrem/y.. 1s
the value at sea level for middle latitudes (para. 8 andtable I). The terrestrial gamma-radiation results fromthe gamma activities present in the soil, buildings andair and the average tissue dose-rate of 50 mrem/y takes
int~ account absorption of radiation by the outer tissues
217

and also the relative time spent indoors and outdoors.
Internal irradiation of man arising from the presencein the body organs of naturally occurring radio-active
nuclides-K.o, C1 4, H 3 and various decay products of
the uranium and thorium series-is extremely dependent
on geometrical considerations and average dose-rates invarious tissues are given in table XXII. The dose-rate
to the lungs due to the natural radio-activity content of
the air is not presented in table XXII but, as mentioned
in paragraph 42 above, this dose-rate is higher than thatto any other body tissue. The dose-rates due to H 3 arevery small in comparison with those due to the radionuclides given.
95. The total dose-rates in the body tissues given intable XXII may be considerably in error owing to uncertainties of the individual components. These uncertainties are discussed in the text of the present annex,
and it is anticipated that more truly representative values
will become apparent as further investigations are made.
It is felt that where a representative value for the natural background dose-rate to individuals in "normal"
TABLE II.

areas is required, the best value which can be recommended at the present time is about 130 mrem/y.
TABLE I.

VARIATION OF TOTAL COSMIC RAY COZ.."TRIBUTION TO
TISSUE DOSE-RATE WITH ALTITUDE AND L.<\.TITUDi:

Total cosmie radiasion tisme
dos• ras. in mrem/:I"

Altilauk(km)

0 •••.......•...•........
1. ..................... .
2 •.••••.••••••••...•..•.
3 ..•.•.•.•..............
4 •.••.....•.............
5 .........•.............
10 ...................... .
15 .•.....................
20 .......•..•............

35
60
100
170
26-0
400
1,400
3,000
3,500

40
70
130
220
360
580
2,300
5,000
6,000

50
90
170
300
500'
800
~.500

11,00014,000*See annex A for RBE values used.
•• Distinction between geographical and geomagnetic latitudes
is not justified.

PHYSICAL DATA FOR RADIATION FROM CERTAIN NATURALLY OCCURRING RADIO-ACTIVE NUa.IDES 149

NuclithCommonSymbolHa .. ••····

Be7 ••••••••

cu ........

Na 12 •••••••

pn ........

5" ........
K'o ........
Rbn •••••.•
1..a1n .•.•..
Sm1u •.•.••
Lune.• ....

u=• .......

ThS3• •.••••
Pa•mi •.••.

u:u• .......

Th:UO. • • • • •Rat21 •..•.•
Rn:ll, •.•.•
Po"'· •.••.
Pb 114 ••••••
Bin• •••...•

Po114 ••••••
Pb 118 ••••••
Bi:10m .•••••
p 0 210 • • • • • •Th:t1 2 ••••••
Ratn •••.••
Ac121 ••••••
Th:n •••.••
Rasu •••••.
Rnno •.....
Pone ...•.•
Pb 211 • • • • • •Bi:U ...•••.

pons ......
TklDI •• •, • •u:w .......
Nps"' ..••..
Pu 21 ~ • • • • • •nameTritium
Beryllium-7
Carbon-14
Sodium-22
Phosphorus-32
Sulphur-35
Potassium-40
Rubidium-87
Lanthanum-138
Samarium-147
Lutecium-176
Uranium I
Uranium X1
Uranium X2
Uranium II
IoniumRadiumRadon
Radium A
Radium B
Radium C
Radium C1
Radium D
Radium E
Radium F
Thorium
Mesothorium I
Mesothorium II
Radiotliorium
Thorium X
ThoronThorium A
Thorium B
Thorium C
Thorium C1
Thorium C 11
Uranium-235
Neptunium-237
Plutonium-239

Radio-utir1
half-life

12.26 y53 d5,760 y2.58 y14.3 d87 d
1.3 x 10'y
4.8 x 101Dy
1.1 x l()lly
1.2 x l()lly
2.2 x 101 8y
4.51 x 10'y24.1 d
1.18 m2.50 x 10'y
8 x 10'y1,620 y3.823 d3.05 m26.2 m19.7 m
1.6 X 10- 4s
20y
5.0 d
138.4 d1.41 x 101Dy
6.7 y
6.13 h
1.91 y3.64 d55 a0.16 s10.64 h60.5 ~
3 X 10-1s
3.1 m
7.1 x 108y
2.2 x lO'y
24,300 y

Parlicl• enerties in MeV
and percentaies 'IJ'Me .i:..own*

p- 0.0186(100)EC
p- 0.165(100)p+ 0.54(90)EC(10)p- 1.71
p- 0.167
p- 1.32(89)EC(ll)p- 0.27
EC(70), p- 0.20(30)a2.20
p- 0.42(100)a4.19, -, CE, SF
p- 0.19(65), 0.10(35)p- 2.31, -(99), IT(!)
a4.77(72), 4.72(28), -, SF
a4.68(76) 4.61(24)a4.78(95), 4.59(4), a5.49(99+), 4.98(0.08), 4.83
a6.00(99 +) p- (0.02)
P-1.03(6), P- 3.18, -(99+)a5.51, -(0.04)
a7.68
fr 0.017(85),0.063(15)P- 1.16(99+ )a(0.02)
a.5.30, a4.01 (76), 3.95(24)p-<0.02
p- 1.11 (53), 0.45-2.18
a5.42(71), 5.34(28), a5.68(95), 5.44(5)a6.28(99+ ), 5.74(0.3)
a6.78{3- 0.34(84), 0.58(12), p- 2.25, -(64), a6.09, -(36)a8.78
p- 1.80(47), 1.~2.38
a4.18-4.56, SF
a4.52-4.87
a5.15(i2), 5.13(17), 5.10(11), -, SF'Y energi., ;,. MeV andfleruntaiu trlaere knoins*

No.,,••
0.477(12)No 'Y
1.28(100)
No 'Y
No 'Y
1.46(11)
No 'Y
1.43(70), 0.81 (30)No 'Y
0.31 (100), 0.20(100), 0.088(100)0.048(23)0.092, 0.063, 0.029
0.043, 0.23-1.83
0.053, 0.118
0.068, 0.142-0.254
0.187(4), 0.51 (0.08).
No 'Y
0.352, 0.295, 0.053-0.259
0.61, 1.12, I. 76, 0.45-2.43
No 'Y
0.046(15)No.,,
0.80(0.001)
0.059(24)No 'Y
0.057' 0.10, 0.91, 0.078-1.64
0.084, 0.212, 0.137, 0.169
0.241 (5)0.54(0.3)
No 'Y
0.239(84), 0.30, 0.115-0.41
0.040(25), 0.73(6), 1.62, 0.124-22
No 'Y
2.61 (100), 0.58(77), 0.51 (30), 0.040--1.09
0.185(55), 0.143(12), 0.095(9), 0.074-0.38
0.087(14), 0.029(14), 0.057-0.200
0.013(17), 0.051. 0.038-0.42( <0.001)

inten!itiei rather than photon intensities; they also include conversion-electron intensities.
•• "No 'Y" means that gammas have been searched for but notfound (excepti~ perhaps X-rays from electron capture).
C E =conversion electron.
E C=electron capture.
I T=isomcric transition.
SF ~spontaneous fission.

•Beta and gamma energies (MeV) are limited to four plus a
range, given in order of decreasing intensity. When known, thepercenta~ of disintegration (intensitv) giving a particular energy
appears m parenthesis following the energy. The dash between
two energies indicates that there are three or more radiations inthat range of leeser intensities than those already given. A dashfollowing several energies indicates additional energies of lesser
intensity. Percentages applied to gamma energies are transition

218

TAllLE III.

u:ss, Tg232, RA 226 AND K•O CONTENTS IN µ.p.c/G
IN VARIOUS ROCKS (MEAN VALUES)

Type of rockU'"

Igneous rocks •........................ ·{

1.4

Tli"'

Ram

K"

1.3
3.5
2.3

1.3

22
25
29
30

0.5

Granite• ••.•...•.....•.....•••.....•.

·l

3.7
3.1

1.4

3

2.6
13
1.0

1.1

Basalts .••.....•.........••••. , .....• ·{11

8

TABLE IV.

0.9
5......, 3
""15
0.25

0.4

0.7

0.5

0.15
0.1

0.5

22
40
20
4
8

0.1
0.17
0.14

0.7
0.3
0.4
0.7
1
60
60
0.4

38
150
151
41
57
152

153
154
41
57

153

0.5

Volcanic rocks:
Basic lavas ...••......•••..•..•......
Acidic lavas •......................••
Sedimentary rocks ..•......••••.....•..
Sandstones ..•..........•..••........
Sandstones •.•..•.•.••.•.••••.•••.•.•
Limestone .••••......••.••...•..•.•••
Limestone ..•.......•.••••..•........
Limestone •••...........•.•••.••....•
Alum shales, Sweden •........•.•••...
Alum shales, Sweden •.•...•••........
Shales .•............•••.•••..•...••.
Bituminous shale, U.S.A....••••..•...
Phosphate rocks, Florida ...•.....••..•
Phosphate rocks, Nauru •.•...••..•..•
Phosphate rocks, N. Africa .••••.......
Phosphate rocks, N. Africa •••..•......

&/treriu

9

2.3
2.5

2.5
29
2.3

155
155
153
150
41
150
41
42
41
42
150

152
152
156
153
57

0.8
1.0

MEASURED TERRESTRIAL GAMMA DOSE-ii.ATES OUT OF DOORSIN VARIOUS COUNTRIESCountry

Austria .......•.•.••....•.......
France •.•.........•.........•...
Japan •.•............•.....••••••
Sweden• .•.•••...••...•.••....••
UK .•.•....••..•.....•...•...•.•
USA* ...•••••••...•.•••...•..•.

Dou rau in air
mra'IY

Commenl

47-56
45-90
{180-350
23-37{ 79-11970-10060-120{ 50
18-01{ 77-15545-130Limestone
Granites and shales
Kanto loam
Granite areas
Stockholm street
Igneous rocks
Clay
Sedimentary rock or clay
Granite areas
Measurements in 23 States

157
158
159
159
160
160
160
53
53

161

•Values obtained by subtraction of an experimentally determined value of 28 mrad/y toallow for cosmic radiation at sea level and appropriately larger quantities at various altitudes.
TABLE V.

Counlr1

Austria .••••••.•MEASURED TERRESTRIAL GAMMA DOSE-RATES IN AIR INSIDEBUILDINGS IN VARIOUS COUNTRIESDose rale in air
mrad/y{ 47-56
65-75

75-112
Japan ••••..••...
Sweden* .•......
UK ••••.........
USA .........•.

{ 48-68
29-1-180-100{ 48-57
99-112158-202{ 85-300
32-57
29-90

Commenl&fere11U

Wooden house
Brick or conc.-ete
GraniteConcrete
Wooden (Tokyo)
Wooden (Kyoto)
WoodenBrickLight weight concrete (containing alum shale)
GraniteOther than granite
17 houses in New York area

157
157
157
162
159
159
42
42
42
163
163
161

*Values obtained by subtraction of 28 mrad/y to allow for cosmic radiation (but this correction is probably too large in the case of multistorey buildings).

219

TABLE VI.

MEAN DOSE·R...TES FROM TERRESTRIAL GAM:!>fA-RADIATIO:-l 01'.L.Y
IN FOUR LOCALITIES IN UNITED KINGDO:!>f53.1-ftan dose•ral<in air.Uean dose-rak in h11man
tissues
mrad/-ymrad/yL«a1ily

Edinburgh ....................... .
Dundee .......................... .
Aberdeenshire .................... .
Aberdeen .....•.................•.

TABLE VII.

0..1 of doers

In houses

48.5
63.0
69.5
104.0

60.0
67.2
81.5
85.3

36
42
50
57

37
43
51
58

NATURALLY OCCURRING RADIO-ACTMTY IN PlJl!LIC WATER SUPPLIES

Water source

RD"' co1uentralion µµc/l

Austria Bad Gastein ......... .
Germany, 7 cities ........... .
Sv.-eden, 2 cities ............. .
UK, ground andsurface v;ater ............. .
Cornish waters ............ .
Devon waters •........•....
USA, tap waterfor 41 cities .•..............
Deep sandstone well, Ill.* .. .
Surface water, III .......... .
USSR, freshwater, (mean) .... .

0.6
0.03-0.3
0.2-1
Up to 0.7
Up to 2.4

Rnm concentration ,,µc/l&/erenu

Up to 220

167
62
169

Up to 200
Up to 3,000
Up to 13,000

61
61
170

Up to 0.2 (average 0.04)
Up to 37
< 0.2

171
172
56
173

•See section VII.
TABLE VIII.

NATURALLY OCCURRING RAD!O-AC!MTY OF NATURAL WATERS AND SPRINGS

um

Ran•
conuntralionµµc/l

conuntration
pµ&/l

Wakr source

Germany, river water •........
UK, river water .•............
US.>\, river water ............ .
Lake water ................ .
Ground water ............. .
Austria, springs ..•............
France, springs .............. .
Germany, springs ............ .
Japan, springs ............... .
Lebanon, springs ............. .
UK, springs ................. .
USA, springs ................ .
USSR, springs and brooks ••....

TABLE IX.

0.07-0.8
0.01
0.03 (1-3)31

0.005-0.01
1.7
Up to 40
Up to 4Rnm
concentration
pµc/l

0.2-0.3

Up to 22Up to 1390.07-18

Up to 0.3 17
Up to 12Up to 10'
Up to 10'
Up to !OSUp to 7 X Hl'
Up to 6 X !OSUp to 7 X 10:
Up to 3 X 105

Up to 3

Reference

62
164
57
57
165
166, 167
158
62
153
39
61
153
168

CoNCENTRATIONS OF RNU2 AND RN220 L"i FREE All!.
AT GROUND LEVEL IN VARIOUS REGIONS

Average co11ce11tratio11 in µµc/l
Rn"' (radon)

Country

Austria ................................. .
Czechoslovakia .......................... .
France ............................ ···· ..
Holland (Amsterdam) .................... .
Sweden ................................. .
UK .......................••.............
USA ..•................................. {USSR ••........................•....•...

0.1-0.3
0.03
0.2
0.13
0.1
0.3
Up to 3(smog conditions)
0.25
0.005-0.5

220

Rn"' thoron

0.002
0.006

0.004
0.05

Re/ere nu

157
69
158
174
42
53
175
175
173

TABLE X. AVERAGE CONCENTRATIONS OF R.N~ 22 AND R.N22D IN AIR OF VENTILATED A2'1l
U!.'VENTILATED SWEDISH APARTMENTS AND THE CORRESPONDING CALCULATED
AVER....GE DOSE RATES TO LUNGS~2
Awage concentralion in p,,,:/lArerate dose rak IO lungs in mrem/yRnU•

Wood .•....•••.•.........•.....•
Brick .•••••...•..................
Light weight concrete(containing alum shale) ...•...••.

R11 2n

Rn"'

A•

,a-

A•

sea

0.527
0.909

0.537
0.913

0.02780.0910

0.136
0.450

263
453

73
128

185
582

52
173

1.86

1.86

0.0959

0.461

930

262

640

178

**Condition B: High ventilation rate, 10-1 sec. -1,• Condition A: As..-uming equilibrium.

TABLE XI. AVERAGE RN222 CONTENT INDOORS AT v.uious LOCAUTIES42
A rerage Rn concentration

Counlry and locakA•erate Rx conunkalUmp,,,:/lCounlry and local.

Canada, laboratory ••••.•.•••••••••
UK .•....••.•••••...........•...

0.05-30.08

Sweden:Wooden apartments ••.••..••••..

0.5

Brick apartments .....•••.....••
Concrete apartments ••.•....•..•
USA, laboratory ••••.•..•......•..
USA, laboratory .••••••...•.•.....
USA, laboratory ••••••••.••.....•.

,,.,,.e/I

0.9
1.9
0.9-1.0<0.1
0.13

TABLE XII. AVERAGE CONCENTRATION OF PB210, BI21om AND Po21D IN AIR AT GROUND LEVEL IN VARIOUS REGIONS
Regi<mRnlll tloS<ghld #oducl

A oerate coneentralion
in air ,,.,,ell

Referenee

Pbno
Pb SIDPb210

3 x 10-1
10-li
5 x 10-1

176
70
173

UK •••••••.•....
USA •••••••.••..
USSR •••••••••••

RegionRn"' tlowihler #oducl

Arerage coneentrationin air p.p&/l

Rt:/ermu

Binom
Pono

4 x 10-1
0.4 x 10-1

173
176

USSR ••••.•••..•'CK ••.•...••....

TABLE XIII. RADIUM-226 IN FOODSTUFFS (µµc RA226 PER KG ORIGINAL MATERIAL)

Food 1ype

Whole wheat bread .••...
White bread ••••••••.••••
Flour-white •••••••••••.
Milk-liquid .••••••..•..
Potatoes .•••.•.•..•..•••
Macaroni. .••.••••.•.••.
Dried beans .............
Canned vegetables .•••..•
Fresh vegetables •••••••.•
Root vegetables •••••••.••
Canned fruit ............
Fruit juices ••••.••.•.••.
Fresh fruit •.•••...••.•••
Rice •••.••••••••...•.•••
Eggs ........•..••••..•.
Fresh fish ..•....••..•..•
Shellfish ••••.••..••..•••
Meat ........••..•.•.•.•
Poultry .•...••.••.•• • .•.

San Francisco

Chicaio

N<VJ York Cily

SJUWY 2
Ju,..1960

Surwy J
Otl. 1960

Swney 1
!Jay 1960

3.2
3.2
2.7
0.25
2.0
2.1
6.1
2.2
2.4
3.4
0.37
1.6
1.5
1.5
4.1
1.2
1.2
0.44
0.73

1.2
1.5
1.7
0.24
2.5
1.8
3.2
0.54
1.2
2.3
0.37
0.49
2.8
1.0
7.9
0.68

3.5
3.3
2.4
0.24
1.4
1.6

Sunty 2
&pl.1960

Suney 2
Aut.1960

Suney J
Jan.1961

2.9
2.0
2.0
0.22
0.77
1.9
2.5
1.1
0.57
1.8
0.26
0.86
0.57
0.37
2.1••
1.0
1.7
0.64
1.4

2.8 ..
2.9
1.34
0.22
1.0*
1.2
2.3
0.91
0.66
2.6*
0.5
0.71
0.91
0.63
2.6
0.8
2.0
0.81
1.9

2.8
2.5
0.83
0.2
2.0
1.7
4.1
1.0
0.84
2.4
0.73
0.62
0.65
0.8
1.9
1.2
1.0
0.55
0.49

1.0•
1.8
2.2
2.0•
1.2
0.68
1.4
0.7
2.7
0.71
2.5
0.45
0.79

1.1

0.47
0.86

•Data corrected by barium recovery as well as strontium recovery.
••Missing sample. Paired value used for computing sums.
TABLE XIV. RAz26 CONTENT OF VAJUous FOODS rn GEIW.ANYilz
Food

Bread ...•....•..••...•.......••.•\\''bite bread •••.......•...•......••
Wheat flour .••••••••....•••......•
l\lilk ..............•.....••.••...•
Potatoes ........................ ..
Cabbage .•••••••.•••.•••••••••••••

l'IJ&/k/l

food

food

,,.,,.;kg food

2.6
1.7, 3.3
2.7
0.3
0.6, 1.0
1.0, 2.4

Carrots
ApplesEggs
Fish
Pork, beef
Tap water

1.6, 1.7, 6.1
0.9
3.1
2.8, 4.0, 4.0, 6.3
0.8, 1.5, 0.8, 0.8
0.03-0.34 (av 0.19)

221

T ABU: XV.

RA22G COh"TENT ot VARIOUS FOODS IN UNITED KINGDOMle>eFood

ppe/l<tfood

Food

25, 62, 68
1.1
2.0

Cereal .•••...•..•.....•.•................•.•.
Tinned pears .............................••..
Egg., ........................•.•.......••.•.

TABLE XVI.

Sa111pli111 locality

N um/Jar of bo4ies

USA, Rochester, N.Y.................
USA, Rochester, N.Y.................
USA, Rochester, N.Y.................
USA, Northwest Pacific area •••.......
Germany, Frankfurt on Main ••.•.....
Germany, Frankfurt on Main ......... ,

20•
14•

p.p.e/lt.t foodFresh fish (plaice) .••.•.......••.............•
Cockles and mussels .•.•....••....•.......•...
Veal, Sausage ••••.•...............•••..••••..

TorAL B-ODY RA!2B CONTENTS

Co11U1tlTalionRa"'ix lap uattr

950
15
Up to 56

Ra"' body coalelll p.p&

ppe/I

Raxte

Mean

0.04
0.04
0.04
0.001
0.14--0.31
0.2

38-35347-13015-Q513-139130-790

0.04

3-150

118
87
30
47
330
130
(35 inekeleton)
24

USA, Prisoners, 4 mo. detention •.•..••

140
21
499
15 samples
11

3.4

100

USA, Prisoners, 7.6 yr. detention .•••.•

8

3.4

202

US..\, Prisoners, 19.7 yr. detention •...•

11

3.4

236

US..\, Lockport boys .................

8

8

368

USA, Chicago boys .••..•...•.......•

7

0.03

36

USA, low activity water ..•..••.......
USA, high activity water .•...•.......

42
34

< 0.1

USA, New York •••••••.••••....•••••
Six different countries .•••.••.•...•..•
13 different countries., •..•.•.....••..

1.5
18.2, 5.7
0.9, 2.0

ro
33

15-81
36-1400

0.1-10.5

36

TYP• of sample

Rl/n-tnu

Whole body ash
Whole body ash
Body organ ash
Whole body ash
Body organ ash
Body organ ash

177
178
124
179
180
62

Whole skeleton ash
Single bone ash
Bone ashcomposite sample
In vi1Jo, radon inbreathIn rivo, radon inbreathIn vi1Jo, radon inbreathIn vi1Jo, radon inbreathIn vivo, radon inbreathSingle bone ash
Single bone ash

121
121
121
181
181
181
181
181
54
54

" Check series using different methods of measurement.
TABLE XVI!.

RA 2 26 AND PB 2 10 IN B-ONES OF SUBJECTS FROM ROCHESTER, N.Y., USA1 2Z

Concentralio11 ir: (ppc/1 ash :I: 90 Pa cenJ e<n<fidence Intl) X /()I

Barn in Nebraska,
lil!ed in Rochester,

Born in Con1'eclicul,
liw:d in RocliMter,agts 14-43

agu t-68

Skull •..•...•..•.••.....•••
Tibia •••..•••...••.••••••.•
Joint ..........•••••.......
Jaw .•...•.•.•••••.•.••.•..
T11eth ••.....•..••••••.•••.•

Pblll

RatH

Ra"'

Pb"'

70 ::1::4
70 ::1::4
12 ±3
16 ::!:: l
12 ::!:: 1
19 ::1::3

201 ::!:: 15
419::!::14
296 ::!:: 13
152 ::!:: 7

51::!::2
100 ::!:: 7
25 ::!:: 2
25 ::!:: 2
28 ::!:: 2

93 ±5

Born in Florida,
lioed in Roches/a',
aies 49-52

Ra"'

131::!::932 ±3
27 ::1::3
26 ::1::2
27 ::!:: 330 ::!:: 3

90 ::1::9
83 ::!:: 8
49 ::1::4

18 ±4

TABLE XVIII.

RA2H CONTE!'."T OF BONE AND l!USC:U

Vertebraem ...•...............
C!avicle114 ••••••••••••••••••••
Skeletal muscle 114 • • • • • • • • • • • • •Tibia shaft°. . . . . .. .. . .. . . . . ..
FemurG ...•.................•
Muscle&11:1.....................
Bone56 •••••••••••••••••••••••?-.f uscle" . . • . .• , • . . . • • • • . . • . . .

Ra'" conlent/r
ashlo-•""')

Ra"' COflUnl/t.rd tisJue ()( 10-1 p.,.c)

10.7
9.2

3.4
1.1
0.05
5.4
4.8
2.5

ex

Timu

10
10

l0

5

56
37
12
3
3

12
11
245
14.6
12.2

222

Pb"'

366 ::!:: 19
1,330 ::!:: 21
78 ::!:: 6 "71 ::!:: 777 ::!:: 6

TABLE XIX.

MEAN DOSE-RATES (MREM/Y, RBE=lO) TO VARIOUS TISSUESOF NORM.AL HUMANs130

Sz.eklalRa"'
and dauiltl<Ts

Skeklal Ra"'•nd dDughterJ

Sktklal Pli'"and dau1hlers(JS3 equilibrium)(eguilibr•um)(50% eguilibrixm)(60 pµC)

Body lis•""s

Osteocytes (5 µdiameter) ................. .
Haversian canal (10 µlining, 50 µdiameter) .. .
Trabecular marrow ...............••.......

TABLE XX.

(40 µ.µ.c)

10

16

5.4
0.6

8.6

(ZOO µpc)

6.6
3.6
0.4

1.0

5PECI.AL ARE.AS OF HIGH EXTERN.AL RADIATION TO RADIO-ACTIVITY FROM SOIL OR ROCK

E::krnal dose-rau ;,. air(Cosniic plus !4rreslria1)

Ionization chamber
scintillation
counter

1 village with 350 Average 1,600 mrad/y,peak 12,000 mrad/yan
inhabitants,
pasture land andscattered farms
180-350 mrad/yin
7,000,000

Primitive granitic, schistous and sandstone
areas of France-area includes about
one-sixth of French population

Monazite area in Kerala and Madras
5ta~ India-approximately 200 km
Jong and several hundred metres wide
Niue Island, Pacific-volcanic soil andunusually high radio-active content
of plants

Geiger counter and

4,500

Population weighted mean 1,300
mrad/y plus about 200 mrad/ybeta rays148
Maximum external radiation 1,000
mrad/y. High total a-radio-activity
content 50-360 µµc/g in the main
foodstuff-tarom"Hj.ghly
populated"

300 and 400 mrad/y in 2 villages;
4 other villages in same area 110 to
150 mrad/y1"

100,000

Monazite area• of Northern Nile Delta
region, UAR

TABLE XXI.

Ionization chamber
scintillation
counter

Average 500 mrad/y,peak 1,000 mrad/ym

30,000Monazite area in States of Rio de Janeiro
and Espirito Santo, Brazil-sequence ofcoastal strips, each several km long andseveral hundred metres wide
Mineralized volcanic intrusives in States ofMinas Gerais and Goias, Brazil--0 km 2
in a dozen scattered places

CosM1c RAY oosE-R.AT!s IN HIGH .ALTITUDE AREAS AND
CORRESPONDING POPULATIONSH~

Area

La Paz, Bolivia ..•..•..••...
Quito, Ecuador ..•.••.•.••••
Bogota, Colombia .. , •...•...
Cerro de Pasco, Peru .•.....•
Lhasa, Himalayan Area .....

(metres)

Lalilu.U

Cosmic rayconlribulion
to Jissuc doserote )bastd
labk ) mremh

3,630

16°5

270

2,850
2,640

O"
4°N

160

4,259

10°5

3,684

30°N

Altitude

223

°"

150
330
310

P~iox

319,600
212,873
325,658
19,187-20,000

scintillation
counter (Na. I
and plastic
phosphor)
Ionization chamber

Scintillation
counterTABLE XXII.

BODY TISSUE DOSE-JI.ATES DUE TO EXTERNAL AND INTERN AL IRRADIATION FROM
N.4.TURAL SOURCES OF RADIATION IN "NORMAL" REGIONS

rllU mr'Rh,E raliu.s)Douin(see paraira/Jhs Z-3 forSource of irradiation

Gonad

Ha~ersian

canal

Bone
ma"°'°&ference
in tatParagraph 8,
Table I
Paragraph 31

External irradiation:
Cosmic rays (including neutrons} ..•

50

50

50

Terrestrial radiation (including air).

50

50

50

Internal irradiation:
K'o ••.........•.................

20

15

15

Paragraphs
80-81

0.5

5.4

0.6

Paragraph 78

0.8

8.6

1.0

Paragraph 78

0.3
0.7
3

3.6
1.6
3

0.4
1.6
3

Paragraph 78
Paragraph 82
Paragraph 41

Ra 121 and decay products (35 per centequilibrium) ..•.....•..........
Ram and decay products (equilibrium) ..•........•.. ·. · · · · · · · · •Pbiio and decay products• (50 per
cent equilibrium) .•............•

cu .............................
Rnm (absorbed into bloodstream) ••TOTAL ......................

137

125

122

• Pb21° in excess of that expected from Ra:t:a and decay products in 35 per cent equilibrium.

''
I

224

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