IONIZING RADIATION:
SOURCES AND BIOLOGICALEFFECTS
United Nations Scientific Committee
on the Effects of Atomic Radiation
1982 Report to the General Assembly, with annexes

UNITED NATIONSNew York, 1982

NOTE
The report of the Committee without its annexes appears as Official Records of the General Assembly, Thirtyseventh Session, Supplement No. 45 (A/37/45).
The designations employed and the presentation of material in this publication do not imply the expression of
any opinion whatsoever on the part oft he Secretariat of the United Nations concerning the legal status of any country,
territory. city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries.

UNITED NATIONS PUBLICATION
Sales No. E.82.IX.806300PANNEX C
Technologically modified exposures to natural radiation

CONTENTSParagraphs

Paragraphs

INTRODUCTION ....................... .
I. RADIATION EXPOSURES DUE TO
COAL-FIRED POWER PLANTS ..... .

A.

B.
C.

Source terms ................... .
1.
Activity concentrations in coal
2.
Activity concentrations in ash
3.
Atmospheric discharges ..... .
Em·ironmental levels and doses .... .
Other sources of radiation exposure
resulting from the use of coal ...... .

1-4

5-19

81-91

V. ENHANCED EXPOSURES TO COSMIC RAYS ........................ .

92-99

9

10-15
16-19
20-31
32-33

Ill. RADIATION EXPOSURES DUE TO
EXPLOITATION OF PHOSPHATE
ROCK ............................. .

36-80

B.

IV. ENHANCED INDOOR EXPOSURES

5-33

34-35

Doses arising from effluent discharges ........................ .
1.
Effluents from phosphate rockprocessing operations ....... .
2.
Effluents from phosphoric acidplants .................... .
3.
Effluents from uranium recovery operations .......... .
4.
Environmental concentrations
and doses ................. .
Doses arising from the use of phosphate fertilizers ................. .

66-77
78-80

D.

II. RADIATION EXPOSURES DUE TO
GEOTHERMAL ENERGY PRODUCTION ............................. .

A.

Doses ansmg from the use of byproducts and wastes .............. .
Recapitulation .................. .

C.

A.

Passengers in aircraft ............ .
Astronauts ..................... .

92-96
97-99

VJ. MISCELLANEOUS SOURCES OFRADIATION ...................... .

100-135

B.

Consumer products .............. .
1.
Radioluminous products .... .
Electronic and electrical de2.
vices ...................... .
3.
Antistatic devices ........... .
4.
Smoke detectors ...•.........
5.
Ceramic, glassware, alloys,
etc., containing uranium or
thorium ................... .
Other miscellaneous sources of radiation ........................... .

101-131103-116

VII. SUMMARY ........................ .

136-137

A.

38-55
39.40
41-44
45-46

B.

117-118
119-122123-125
126-131132-135

47-55
Page

56-65

Introduction
1. There are circumstances where man finds himself
in a natural radiation environment to which he would
not be exposed if some kind of technology had not beendeveloped. Examples are travelling by air, using natural
gas for cooking or heating purposes. living in the neighbourhood of a coal-fired power plant. The resulting
exposures have been labelled "technologicallyenhanced" natural radiation exposures by Gesell andPrichard [GI], who defined them as exposures to truly
natural sources of radiation (that is, naturally-occurring

References .............................. .

137

radionuclides and cosmic radiation) which would notoccur without (or which are increased by) some technological activity not expressly designed to produce
radiation.
2. In some cases, technology helps to reduce thenatural radiation exposure. For example. when
drinking water supplies are drawn from surface waters,
the use of water-purification processes brings about adecrease in the concentration of radium and othernaturally-occurring radioactive elements. Anotherexample is the burning of fossil fuel, which reduces the107specilic activity of 14 c in the biosphere and therefore
lowers the doses from that radionuclide. This Annex
deals with "technologically modified" exposures tonatural radiation and presents some assessments of thedoses arising from such exposures.
3. The Committee recognizes that the definition given
in paragraph 1 is not rigorous and that, in reality,
radiation is either natural or artificial in origin. It also
realizes, however, that there has been scientific interestin recent years in radiation exposure from the variety ofsources which will be ~iscussed in this Annex. The
Committee believes that consideration of these sourcesin a separate Annex is justified at least for this report.
4. Although they do not properly fall within the above
definition. there are a number of other sources of
exposure to radiation which are a direct consequence of
man's technological activities. and which are included
for convenience within this Annex. Examples of these
are consumer products incorporating radionuclides.
and electronic and electrical devices. Other man-madesources of exposure such as the explosion of nuclear
devices and the operation of nuclear power plants are
discussed in Annexes E and F, respectively.

I.

RADIATION EXPOSURES DUE TO
COAL-FIRED POWER PLANTS
A.

SOURCE TERMS

5. Coal, like most materials found in nature, contains
trace quantities of the naturally-occurring primordialradionuclides. Therefore, the combustion of coal resultsin the release to the environment of some naturalactivity and in the re-distribution of that naturalactivity from deep in the earth to locations where it canmodify ambient radiation fields and population
radiation exposures.
6. The annual world production of coal (including
brown coal and lignite) was about 3.7 1012 kg in 1979
[US], the main producers being China. the Union ofSoviet Socialist Republics. and the United States ofAmerica. Coal is used most commonly for industrial
purposes, power generation. and space heating. In 1974.
about 70% of the coal consumed in the United States
was burnt in electric power stations, while only 2% wasused for space heating in household and commercial
markets [U3]. The situation may however be quite
different in other countries. In Poland, for example,
about 15% of the coal consumed in 1976 was burned ashousehold fuel [G10].

as the activity concentrations in coal. the ash content of
the coal, the temperature of combustion, and theefficiency of the filtering system. Marked differences
should therefore be expected between the measured
activities discharged per unit energy produced fromdifferent power plants. The currently available information on the activity concentrations in coal and ash
and on the atmospheric discharges will be brieny
reviewed.

I.

9. Since the publication of the 1977 report of
UNSCEAR [U2]. a substantial number of publications
have dealt with the measurement of activity concentrations of natural radionuclides in coal. Table 1 presents
results of measurements of radionuclides in coalsamples originating from mines or from power plants.
The most significant study is that of Beck et al. [B2],
who listed the concentrations measured in almost 1000
samples obtained directly from mines providing mostof the coal presently used in the United States. Theseauthors found that the activity concentrations measured
in the coal samples varied over two orders ofmagnitude (0.7 to 70 Bq kg-1 for 40K, less than 3 to 520
Bq kg-1 for mu, and 3 to 320 Bq kg-I for 232Th). Variations can be quite large even in the same area.
Gluskoter et al. [G2] obtained concentrations ranging
from 4 to 300 Bq kg-1 for 238U, 0.4 to 10 Bq kg-I for
232Th and 3 to 100 Bq kg-1 for 40K in five different
seams of coal mined in Illinois. In general, the concentrations of natural radionuclides in coal are less thanthose in the earth ·s crust. Occasionally, however,usually as a result of leaching from abnormally
radioactive overburdens of volcanic origin, very highconcentrations of some radionuclides, in particularuranium. can be found in various coal deposits. Those
uraniferous coals are the exception and occur almost
invariably in low grade coal deposits [Al, 01, VI, V2].
It will be assumed in this Annex that the average
activity concentrations in coal are 50 Bq kg-I of 40K
and 20 Bq kg-1 each of 238U and 232Th and that all the
decay products of 238U and of 232Th are in radioactive
equilibrium with their precursors. although that might
not be always the case for 210Pb and 210po (see forexample the results of Kaakinen et al. [Kl] in Table 1).
Enhanced activity concentrations of 210Pb could
conceivably occur if large quantities of 222Rn diffuse
from adjacent high activity rocks into a lower activity
coal seam with subsequent trapping of the decay
products in the coal [82).

2.
7. In view of the importance of coal for generating
electricity. this section will deal essentially with theradiation exposures arising from its use to produce
electric power. Most documented exposures are thosedue to the atmospheric releases of gases and particulates from power stations. There is more particulate
emission during combustion of coal than of any otherfuel because of its high ash content: for example, theash content of coal burned in the United States in
power plants with a capacity of more than 25 MW(e)ranged from 4 to 25% in 1977 [WIO]. The combustion of
about 3 109 kg of coal is required to produce anelectrical energy of 1 GW a [BJ, El, Kl, K2].

8.

The activities of natural radionuclides discharged
in the atmosphere from a power plant per unit electricalenergy produced depend on a number of factors such
108

ActMty concentrations in coal

Activity concentrations in ash

10. In the production of electric power, coal is burnedin furnaces operating at temperatures of up to l 700o C.
Most of the mineral matter in the coal is fused into avitrified ash. A portion of the heavier ash, along withincompletely burned organic matter, drops to thebottom of the furnace as bottom ash or slag. The
fly-ash, however, is carried through the boiler alongwith the hot nue gases and any volatilized mineralcompounds to the stack where, depending on theefficiency of emission control devices. some fraction iscollected while the rest (escaping ny-ash) is released tothe atmosphere [B2].
11. The radionuclides included in the non-combustible mineral matter are thus partitioned between thebottom ash and ny-ash. except for the gases and volati-lized minerals which will be incorporated directly into
the nue gases. Table 2 presents a list of reported activity
concentrations of natural radionuclides in bottom ash,collected ny-ash and escaping fly-ash. Owing mainly tothe elimination of the organic component of the coal,
there is very approximately an order of magnitudeenhancement of the activity concentrations from coal toash. Consequently, the natural radionuclide concentrations in ashes and slags from coal-fired power stations
are signilicantly higher than the corresponding concentrations in the earth's crust [L4]. The arithmetic
averages of the concentrations in escaping fly-ash from
Table 2 are, in 13q kg-I, 265 for 40K, 200 for mu, 240
for 226Ra. 930 for 2l0Pb. 1700 for 21oro, 70 for 232Th,
110 for 228Th and 130 for 228Ra.

In

...

J.O

\

0 llOF:,••• 2l!JlJ••,ZZL;,12. In the United Slates. a number of recent studies
have aimed at understanding the mechanisms ofaerosol formation in the coal-fired power plants [Cl,Kl, K2. K3, Ll, N2, 01, Rl]. It has been observed thatcertain trace elements partition unequally between
bottom ash and fly-ash. They become concentrated on
the smaller fly-ash particles which have larger surfaceto-volume ratios as the hot flue gases cool down on
their way to the stack [Kl, K2, Ll, N2, Rl]. This
process results in the depletion of certain elements inbottom ash and their consequent enrichment in fly-ash,
an effect which increases as the size of the fly-ash
particles decreases [Cl. Ll, N2). These smaller particles
are Jess efficiently collected by emission control devices
such as electrostatic precipitators and scrubbers, andthus preferentially escape from the plant.

13. The apparent enrichment of some radionuclides inescaping fly-ash particles can be characterized by theenrichment factor EF, defined as the ratio of theconcentrations of the radionuclide (X) and of 40K in thesample divided by the corresponding ratio in coal:
EF = (X) sample/ (4°K) sample(X) coal/ (4°K) coal(I)

Potassium-40 is used as a reference because its activity
concentration remains more or less constant in all typesof ash in a given plant and thus is assumed to be a
tracer for the alumino-silicate dominated ash matrix[Cl]. Figure I shows the variation of the enrichment
factors of 238U, 226Ra, 228Ra, 21opb and 228Tb as afunction of the size of the escaping fly-ash [Cl]. The
enrichment factors given in that figure are derived frommeasurements of samples obtained at a power plant
equipped with Venturi scrubbers and electrostatic
precipitators [Cl]. The escaping fly-ash was collected bya large cyclone separator: the four fractions obtained
had measured mass median diameters of 18.5, 6.0, 3.7,
and 2.4 µm and count median diameters of 2.7, 2.6, 1.1,
and 0.9 µm, respectively [F6]. Among the radionuclides
measured by Coles et al. [Cl], the most enriched was
21opb, followed by 238U, 226Ra, 228Ra and 228Tb. It is
likely that a large fraction of 21DPb and 21opo volatilizes
during the combustion, then condenses somewhere
down the flue line on the finer fly-ash particles, whereas
40K and isotopes of thorium melt with the aluminosilicate minerals and drop out as bottom ash or coalesce
and are carried through the flue line as ny-ash particles.
According to Coles et al. [Cl). the uranium isotopes
could behave in either way according to their mineralogical or chemical form in the coal; the uranium that is
associated with the clays, or which is mineralized ascoffinite, would remain with the bottom ash whereas
the uranium that is dispersed in the coal as uraninite
could become volatile as U03 and later condense on the

C <21\,O 218:"
l 0

1.0

10
PARTIC\.E srze"

Flfure I. Enrichment factors of 21opb, 238U, 226Ra,
22 Re end 228Th versus size (mess median
diameter) In stack fly-ash collected downstream
from an electrostatic preclpltetor [C1]fly-ash particles [Cl]. As a decay product of mu, 226Ra
would behave in an analogous manner: on the other
hand, 228Ra, as a decay product of 232Th, would tend tobe associated with the matrix of the fly-ash particles.
14. The mechanisms described above are supported
by evidence from studies of fly-ash particles whichshow that they consist of an insoluble matrix composed
mainly of iron and aluminium silicates coated with alayer of soluble compounds [K3, Ll. P3]. However.
other physical-chemical processes such as segregation(diffusive transport to the surface of the particle) andgas-surface reactions may also contribute to the surface
enrichment of the ash particles [Sll ). Table 3 presents
published enrichment factors, which may or may notuse 40K as a reference, while Figure II, extracted from astudy made in the Federal Republic of Germany, illustrates the increase in specific activity as one proceedsfrom one stage of particle retention to the next [C5, 17].
As expected, the enrichment factors are higher for 21opb
and 21opo (range of 1 to 11) than for uranium, radiumor thorium (range of 1 to 2). As a general rule, thevalues of the enrichment factors increase with thetemperature of combustion and decrease with theparticle size, at least for sizes above 1 µm.
15. Measurements of the size distribution of escaping
fly-ash particles are very few. In the Federal Republicof Germany, a nearly log-normal size distribution has
been found with an activity median aerodynamic
diameter of 3-5 ~Lm for uranium, thorium and radium,and of about 1 µm for 210Pb and 21opo [J7]. In the
United States, the size distribution of particles collected
in a plant down-stream from an electrostatic precipitator has been found to be bimodal, the two modes
being at 0.06 and 0.5 µm [01). A similar size distribution, with two modes at 0.04 and 0.25 µm, has been
observed in the plume of a coal-fired power plant [P3].
The mass activity concentration of enriched radionuc-109

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Figure II, Measured mean values of specific activity In the coal,In the fly-ash deposited In the electrostatic filter stages and In
the escaping fly-ash [CS]tides, such as 21opb and 210Po, may be much higher inthose small particles than suggested by the values given
in Table 3 and Figure I [N2, 01]. However, an analysisof the submicron particles with respect to the concen·
trations of elements volatilized during combustion has
shown these concentrations to be independent ofparticle size, in contrast to the larger particle sizes
where an inverse relationship with particle size applies[S12). These results would be consistent with amechanism for formation of submicron particles
involving "bursting" of larger particles due to gas
release during rapid heating, followed by coagulationand condensation of volatilized elements to form
particles in the 0.1-1.0 µm size range [S12].
3.

Atmospheric discharges

16. The atmospheric discharges of natural radionuclides are obtained as the products of the mass of fly-ash
released per unit of energy produced by the activity
concentrations in escaping fly-ash. The mass of fly-ash
released per unit of energy produced depends heavily
on the efliciency of the particulate control. In the
United States, the average atmospheric releases in 1972
from 696 major steam plants amounted to about 8% of
the total ash in the coal burned [M3, F5]. However, allplants in the United States must eventually meet theclean air standards of the Environmental Protection
Agency which are set at 1.4 ]06 kg of ash per GW a ofelectricity generated [M3), which corresponds to a
110

release of about 1% of the total ash. The averagereleases in that country are thus likely to lie at present
between those two values. In the Federal Republic of
Germany, the emission of dust is limited by the legal
authorities at 0.15 g per mJ of flue gas, which corresponds to a release of about 1% of the total ash [Sl]. In
Italy, typical coal-fired power plants are equipped withelectrostatic precipitators allowing an ash retention of
95%, and thus a release of 5% [Ml). In Poland, thefraction of ash released is estimated at 20% [J4], while inIndia it has been assumed to be 10% [M12]. With regard
to the USSR, it has been reported that the modern coalfired power stations are equipped with electrofilters
allowing an ash retention of 98.5-99%. However, there
are other power stations for which the efficiency ofretention of the fly-ash particles is about 90%1, corresponding to an atmospheric discharge of about 10% of
the ash produced. So the power plants which have thesame power as the Zaporozhje station (1.2 GW(e)) andan ash retention efficiency of 90%, burning 3.4 1Q6tonnes of coal with a high ash content (35-40%),
discharge about 1.3 105 tonnes of ash to the atmosphereannually [K 11, 11, 15].
17. It thus seems that by and large there are two typesof coal-fired power plants throughout the world,
namely those which release about 10% of the total ash
produced and those, equipped with sophisticatedretention devices, which release only about 1% of theash. Although it would probably be more realistic toestimate the radiation impact resulting from the releases

of the two types of plants, it has been decided in thisAnnex to derive only one set of activities discharged
per unit of energy produced.
18. Table 4 presents the estimates of atmosphericdischarges adopted in Annex B of the 1977 report of
UNSCEAR [U2] and other estimates which originate
mainly from highly industrialized countries and were
published after the preparation of the 1977 report. On
this basis, "average" discharges have been estimated forthe purpose of assessing the doses arising from coal
combustion in power plants. Those "average" atmospheric discharges per unit energy generated are alsopresented in Table 4; in terms of MBq (GW a)-1, theyamount to 4000 for 40K, 1500 for 238U through 226Ra.
5000 for 210pb and 210Po, and 1500 for the radionuclidesof the 232Th decay series, from 232Th to 224Ra. These
normalized discharges are taken to be representative of
the current situation on the world-wide scale. For the
purpose of comparison with the values given in theprevious paragraphs, it can be calculated that theycorrespond, for example, to a plant burning coal with a
10% ash content and equipped with a filtering systemallowing an ash retention of 97.5%, the enrichment
factors would be 1 for 40K, the isotopes of radium,
uranium and thorium, and 3 for 210Pb and 21opo.
19. Releases of 222Rn and of 220Rn have to be
estimated separately as radon is not collected by theparticulate control devices. The activities of 222Rn and
220Rn released per GW a l:,lave been assessed at 60 GBq
on the basis of the following assumptions: 222Rn and
220Rn are in radioactive equilibrium with 238U and
232Th. respectively, in coal and are discharged in their
entirety when coal is burned; the average activity
concentration of 238U or 232Th in coal is 20 Bq kg-I;
and the combustion of 3 109 kg of coal is required to
produce 1 GW a of electrical energy.
B.

ENVIRONMENTAL LEVELS AND DOSES

20. Measurements in surface air. carried out about ten
years ago, had clearly shown the presence of enhanced
concentrations of the natural radionuclides precursorsof the radon isotopes. Bedrosian et al. [B3] measured
downwind of a coal power plant in Alabama, concentrations of up to 50 µBq m-3 of 226Ra, 10 µBq m-3 of
232Th and 100 µBq m-3 of mu. compared with the"normal" concentrations of about 1 µBq m-3 for each of
the three radionuclides. However, recent measurements[F2, S2, TI] have failed to reveal a significant increasein the surface air concentrations around the plant. Thisis probably due to the fact that the activities discharged
are smaller now than what they used to be; anotherreason is the taller stacks which result in a much greater
atmospheric dilution [B2].
·21. Snow, which can be expected to have a low
background concentration of the natural radionuclides
considered. was sampled by Jaworowski et al. [JS]around coal-fired power plants. The measured 226Ra
concentrations ranged up to 60 mBq kg-I and wererelated to the distance from the power plants. In
addition. studies of a glacier 150 km away from a Polishindustrial centre have revealed a 50-fold increase in
226Ra concentration over the preceding 80 years [J5].

layer of soil. measurements in soil have been conductedby several investigators. In Poland, the concentrationsof uranium, thorium, and 226Ra were found to be higher
in the upper 5 cm layer than in the 5-10 cm layer ofsoils of industrial areas, while this effect was notobserved in rural soils [J2]. In the United States, Beck et
al. [B2] attempted to detect increases in natural radionuclide concentrations in surface layers of soil in theenvirons of three large coal-fired power plants, but only
obtained positive results for the oldest and most poorly
controlled of the three plants. Other recent studies [F2,S2] have also been unsuccessful. The annual
enhancement in the concentrations of 238Th, 226Ra and40K in the upper 30 cm layer of soil within 20 km ofcoal-fired power stations has been theoreticallyestimated in a study of the USSR to represent, on
average, only 0.08%. 0.12%, and 0.03% of the corresponding typical natural concentrations in soil [L4].
23. Th'e main pathways through which the populations living around coal-fired power plants are ex,posed
to enhanced levels of natural radionuclides are inhalation during the passage of the cloud, and external
irradiation, inhalation and ingestion resulting from theactivity deposited on the ground.
24. The collective dose commitments due to inhalation during the passage of the cloud have been roughly
estimated as follows. Assuming that there is no decay
during the atmospheric transport, all the activity
released Ao (Bq) will eventually be deposited on asurface S (m2). The average activity density is A0 /S (Bqm-2) and corresponds to an integrated atmosphericconcentration at ground level of A0 /S Vd (Bq s m-3),
where Vd is the deposition velocity. The collective dose
commitment~ in organ or tissue q is given by:
A0
Dq
MC =-S6NBq
vdS
Iih

where Yd = 10--2 m s-1, value which takes into accountboth dry and wet deposition; S6N is the population
affected, which is the product of the area of thedeposition region S and of the population density 6N,
assumed to be uniform and equal to 1 Q-4 m-2 around theplant. The areal dependence is removed by the productof the quantities A 0 /vdS and S6N; B is the individual
adult breathing rate, taken to be equal to 2.3 lQ-4 m3 s-1;
Dq/lih is the committed absorbed dose in organ or
tissue q per unit activity inhaled (Gy Bq-1). In thisassessment, the values adopted have been derived fromthose calculated by Jacobi [J7] using a quality factor of
20 for a particles (Table 5). These figures were
estimated assuming that the radionuclide content of theparticles was 80% insoluble and 20% soluble and using
ICRP dosimetry [16]. No account is taken of thepossible reduction of the atmospheric concentrationindoors.
25. This method was used to calculate the collective
dose commitments during the passage of the cloud formost of the natural radionuclides, one notable
exception being 222Rn and its short-lived decay
products. In that case, the activity A 0 of radon distributed over a surface S of land was compared to thequotient of the atmospheric concentration and of thenatural emanation rate for 222Rn. One obtains

Mc = Ao
22. Since the concentrations in fly-ash are on averagea few times higher than the corresponding concentrations in soil, and since the activity deposited remains
for a relatively long period of time in a thin superficial(2)q1.8 (Bq m-3)
S6N B Dq'
S 2 10- 2 (Bq m- 2 s- 1)
I;h

(3)

where Ao is the activity of 222Rn daughters associatedwith the release of 222Rn (the equilibrium factor

111

between 222Jln and its daughters is taken to be 0.6);
1.8 Bq m-3 is the average outdoor equilibrium equivalentconcentration of222Rn over land and 2 10-2 Bq m2 s-1 isthe average emanation rate of 222Rn (see Annex D); asin the previous paragraph, the values of 6N and B are
taken to be equal to lQ-4 m-2 and 2.3 lQ-4 m3 s-1, respectively: the values of Dq/l;h are derived from Annex D
and presented in Table 5.
26. The collective dose commitments due to inhalation during the passage of the cloud, as estimated by themethods described above, are presented in Table 6 forthe most important radionuclides discharged into theatmosphere as a consequence of the production of
1 GW a of electrical energy by coal-fired power plants.
The c-0rresponding effective dose equivalent commitments are also included in Table 6. The doses due toinhalation of 220Rn and its decay products, estimated ina similar way, are found to be about 1000 times smaller
than those from 222Rn and its decay products; they
have been neglected here. Finally, the doses from 4-0K
were not calculated because of the homeostatic control
by potassium in the body.
27. The collective dose commitments incurred after
deposition can be very crudely evaluated bycomparison with the natural soil activity concentrations
and the corresponding annual absorbed doses in tissues
given in Annex B. Assuming that the deposited activity
becomes unavailable to the vegetation with a mean lifeof 100 years for all the natural Jong-lived radionuclides,
and that only the upper 30 cm of soil are involved in
the uptake of radionuclides by vegetation, the collective
dose commitments per unit energy generated, M.1, due
to deposition can be assessed as

Mc _ A0 Dq 6N l"
qhC

(4)

where Ao is the activity associated with the release of agiven radionuclide: Dq is the natural dose rate in organor tissue q due to the radionuclide under consideration;
ON is the population density; ,: is the mean life of thelong-lived natural radionuclides in soil taken to be 100
years; h is the thickness of soil involved, expressed as
mass per unit area (assumed to be 500 kg m-2); and C is
the natural concentration of the nuclide in the soil. In
the case of the short-lived radionuclides, especially theisotopes of radon and their daughters, the major
contribution to the source term A 0 , arises from thedecay of their long-lived precursors in soil.
28. The collective dose commitments per unit energy
generated obtained in this way are presented in Table 7
for external and internal irradiation. It should be notedthat the values chosen for Dq correspond to theassumption that the contaminated soils and rocks will
not be used as components of the building materials.
With respect to internal irradiation, the ny-ash particles
have been assumed to behave physically and chemicallyin the same manner as the soil particles, even though
the fly-ash particles, being in a vitrified form, are highly
insoluble. On the other hand, the doses resulting fromdirect deposition on vegetation and foodcrops have notbeen taken into account. The collective effective dose
equivalent commitments corresponding to thecollective dose commitments presented in Table 7 havealso been calculated; they are included in Table 7.
29. The conversion of the collective dose commitments into collective effective dose equivalent commitments allows a better evaluation of the impact of the112

various radionuclides and of the various pathways.
Table 8 summarizes the collective effective dose equivalent commitments arising from the atmosphericdischarges of coal-lired power plants. The productionof one gigawatt year of electrical energy is estimated tolead to a total collective effective dose equivalentcommitment of 2 man Sv. Inhalation during the cloud
passage and internal irradiation due to the activity
deposited are found to contribute signilicantly to thetotal collective effective dose equivalent commitment.
The predominant radionuclides are the isotopes ofthorium with regard to inhalation during the cloud
passage and 2tOPb and the isotopes of radon withrespect to internal irradiation due to the activity
deposited. Assuming that 70% of the coal produced isused by the power utilities and that the combustion of
3 109 kg of coal is necessary to generate 1 GW a,
the collective effective dose equivalent commitment
resulting from the use of coal in 1979 is estimated to beabout 2000 man Sv. on the basis of a world coalproduction of 3.7 1012 kg [US].
30. The specific activity of t4C in the atmosphere will
decrease as a result of the airborne release from coalfired power plants, thus leading to "negative" collective
dose commitments. The Committee has not calculated a
numerical value to this effect.
31. Annual individual effective dose equivalents
resulting from inhalation during the cloud passage havebeen estimated. Assuming an effective stack height of
100 m and a uniform wind rose, the annual average ofthe ground level air concentration per unit release rate
experiences a maximum of about 4 lQ-8 Bq m-3 per
Bq s-t at approximately 1 km from the stack [C6]. On
the basis of the activity discharged per unit energy
produced given in Table 4 and of the effective dose
equivalents per unit activity inhaled presented in Table
5, the annual effective dose equivalent resulting frominhalation during the cloud passage would be about
5 µSv for an individual of the critical group living
around a coal-fired power plant producing one GW ofelectrical power. The annual effective dose equivalents
due to ingestion and external irradiation could be ofabout the same importance (J7].
C.

OTHER SOURCES OF RADIATION EXPOSURE RESULTING FROM THE USE OF
COAL

32. In the coal fuel cycle, radiation exposures above
the natural background are expected to occur mainly
when coal has been converted into ash. The productionof ash was reported to be 107 tons in 1973 in at least
four countries: German Democratic Republic, Federal
Republic of Germany, Poland and the United States[Gl 1]. Most ny-ash is pumped as a water slurry tosettling ponds but some of it, amounting to more than
35% of the production in Belgium, Finland, France andthe Federal Republic of Germany [Gl 1), is used in avariety of applications, the largest of which is the
manufacture of cement and concrete. Some concretes
contain 80% of ny-ash [T2]. Other major uses are as
road stabilizers, light-weight aggregates, road fill, andin asphalt mix [M6]. Fly-ash is also used to some extent
in agriculture to improve soils [F7, J4]. All those utilizations of ash might lead to increased radiation exposures
but very little has been published in this field.
33. Outside of the coal fuel cycle, the combustion ofcoal for various purposes results in airborne discharges

that have received very little attention. The use of coalfor cooking and heating in private homes may lead tohigh collective dose commitments as the chimneys are
low and not equipped with ash removal systems, and as
the population densities around the sources of emission
are high. Assuming that 5% of the coal produced andthat 50% of the resulting ash escapes to the atmospheremeans that domestic heating contributes about equallywith power production, where 70% of the coalproduced releases 2.5% of the ash. The further
assumption that the population density around thehouses is 104 km-2 leads to a collective cffcctive dose
equivalent commitment due to the world-wide use ofcoal in 1979 that is very roughly estimated to be of theorder of 105 man Sv.

production of phosphate rock was about 1.3 1011 kg in
1977. the main producers being Morocco. the Soviet
Union and the United States [Ul]. Table 9 presents
average activity concentrations of natural radionuclides
in phosphate rock from all major p\losphatc-producing
areas of the world. Sedimentary phosphate ores, such as
those found in Florida and Morocco, tend to have highconcentrations of uranium, whereas magmatic ores,
such as apatite from Kola, do not. Typical activity
concentrations of 2JBU are 1500 13q kg-I in sedimentary
phosphate deposits and 70 Bq kg-I in apatite.
Uranium-238 is generally found in radioactive
equilibrium with its decay products. The activity
concentrations of 232Th and of 40K in sedimentary
phosphate rock are much lower than those of 238U. andcomparable to those observed normally in soil.

II. RADIATION EXPOSURES DUE TO
GEOTHERMAL ENERGY PRODUCTION

37. Mining and processing phosphate ores redistribute 238U and its decay products among the various
products: by-products and wastes of the phosphateindustry. Efl1uent discharges into the environment aswell as the use of phosphate fertilizers in agriculture
and of by-products in the building industry are possible
sources of exposure to the public. This section deals
mainly with the phosphates of sedimentary origin, as
they are the most commonly found and the most likely
to lead to enhanced radiation exposures.

34. Geothermal energy is produced in Iceland, Italy,
Japan. New Zealand, the USSR and the United States.
At the present time, it accounts for only 0.1% of theworld's energy production [U5] but its relative importance may grow in the future as the potential resourcesof geothermal energy are believed to be very large. In
geothermal energy extraction, use is made of hot steam
or water derived from high-temperature rocks deep
inside the earth. The geothermal fluids carry naturalradionuclides and especially 222Rn, which is discharged
into the atmosphere. From measurements of 222Rn
activity concentrations in the hot stream used in three
Italian power plants. the 222Rn annual releases havebeen estimated to be 110 TBq from the 400 MW
Larderello plant. 7.0 TBq from the 15 MW plant at
Piancastagnaio, and 1.5 TBq from the 3 MW plant at
Bagnore [M13]. These figures point to an average 222Rn
atmospheric discharge per unit energy generated ofabout 400 TBq per GW a. The corresponding collective
effective dose equivalent commitment per unit energy
generated is estimated to be about 6 man Sv per GW a
if the assumptions used for the discharges from coalfired power plants are applied. It is recalled that theseassumptions are: equilibrium factor of 0.6 between
222Rn and its short-lived decay products; population
density of 100 km-2 around the plant; effective dose
equivalent per unit activity inhaled of 1.3 l 0-8 Sv Bq-1;
indoor concentrations equal to the outdoor concentrations.
35. Annual individual effective dose equivalents
resulting from inhalation of short-lived decay productsof 222Rn have also been estimated. Assuming. as in thecase of discharges from coal-fired power plants. aneffective stack height of 100 m and an annual averageof the ground level air concentration per unit release
rate of 4 1()-8 Bq m-3 per Bq s-t at l km from the stack,the annual effective dose equivalent resulting fromatmospheric 222Rn discharges would be about 3 l o-s Sv
for an individual of the critical group living around ageothermal plant of 1 GW of electrical power. It is to be
noted that the existing geothermal plants have a lower
power, resulting in correspondingly lower estimates ofannual effective dose equivalents.

III. RADIATION EXPOSURES DUE TO THE
EXPLOITATION OF PHOSPHATE ROCK
36. Rock phosphate is used extensively, mainly as asource of phosphorus for fertilizers. The world

A.

DOSES ARISING FROM EFFLUENTDISCHARGES

38. Effluent discharges into the environment havebeen reported for a phosphate rock processing plant
and two phosphoric acid production plants [P4], as well
as for one uranium recovery plant [D2].

1.

Effluents from phosphate rock processing operations

39. The preparation of phosphate rock generally
involves strip mining to obtain ore, beneficiation toremove impurities, drying to remove moisture, andgrinding to improve reactivity. The major airborne
emissions occur in the form of fine rock dust fromdrying and grinding operations [P4]. The 1976 atmospheric discharges from an ore drying facility in Florida[P4] were about 250 MBq of 238U, in radioactive
equilibrium with its decay products down to 226Ra(Table 10). Since that facility processed about 2.7 109 kg
of wet phosphate rock in the same year, the atmospheric discharges of 238U correspond to approximately
90 Bq per tonne of processed phosphate rock. The
atmospheric releases of 222Rn have not been reported;assuming a 226Ra activity concentration in phosphateore of 1500 Bq kg-1 and, conservatively, a 100% releaseof 222Rn, they would amount to 1.5 106 Bq per tonne ofprocessed phosphate rock.
40. During the beneficiation process, marketable rockis separated from sand tailings and clay slimes. Thesematerials are produced in a 1 :1 :1 ratio. Clay slimes
have about the same activity content as marketable rockwhereas sand tailings are much less active. Mined-out
areas are used in Florida for the disposal of sandtailings and slimes [M4]. Several Florida slime ponds
have discharges to the environment. Although no
chemical process is used to treat the discharges from theslime ponds, the measured activity concentrations of226Ra in liquid efl1uents were all found to be less than
100 Bq m-3. The reduction of total 226Ra from the raw
slime to the effluent, primarily due to the removal of113suspended solids by settling, ranged from 92% togreater than 99.9% [M4]. Table 10 presents the ranges in
226Ra activity concentration measured in the dissolved
and in the undissolved fraction of the slime and of theefnuent in seven mines and heneficiation plants in
Florida [G4]. No information appears to be available to
the Committee on the actual volume of liquid
discharges from those plants.

2.

Effluents from phosphoric acid plants

41. Phosphoric acid is produced by two principal
methods, the wet process and the thermal process. In
the wet process method, usually employed for the
production of fertilizers, sulphuric acid is mixed withground phosphate rock; the subsequent reaction resultsin the production of phosphoric acid and gypsum:
10 H2 S04 + Ca10 F2 (P04)6 + 20 H20 --+ 10 Ca S04.
2 H20 + 2 HF + 6 H3 P04. In the reaction, radium iscoprecipitated with the gypsum, while uranium andthorium follow the phosphorus into the acid, which isthen used to manufacture various fertilizer products.
Table 11 presents the estimated distribution of somenatural radionuclides among various products of thephosphate industry, in the United States, along with thequantities involved [GS].
42. Apart from gaseous fluorides, which are notradioactive. the airborne efnuents of wet phosphoricacid plants consist of dust resulting from the transferring of phosphate rock within the plant. Estimates of
the airborne discharges from two wet process
phosphoric acid plants located in Florida are given in
Table 10 [P4]. The estimated releases, which are basedon the measurement of the total particulate emissions
and of the total activity concentrations of naturalradionuclides in the raw products, are about 100 times
higher in plant B than in plant A. However, a stacksampling survey. conducted by the United States
Environmental Protection Agency to measure theactual emissions from selected stacks at each facility,
showed that the releases from plant B were probably
overestimated [P4]. On the basis of information
contained in reference [P4] and on the chemical
reaction given above, the throughput of marketable orein plant A and in plant B has been assessed to be about
1.2 109 kg. The atmospheric releases of 222Rn have notbeen reported; assuming a 226Ra activity concentrationin phosphate ore of 1500 Bq kg-I and, very conservatively. a 100% 122Rn release, they would amount to 1.5
1()6 Bq per tonne of phosphate ore.
43. Each wet process phosphoric acid plant in Florida
incorporates a large cooling pond (about 2 km2) ofcontaminated water for recycle in the facility. During
periods of excess rainfall, it becomes necessary todischarge water from these ponds to nearby streams[M4]. Raw process water has a pH of 1.5-2.0 andcontains 74 OOO Bq m-3 of mu [G4, M4]. The UnitedStates Environmental Protection Agency permits forphosphoric acid plants usually stipulate an acceptable
pH range of 6-9 for treated effluent. To accomplish
this. slaked lime is normally added. This chemicaltreatment is highly effective in removing naturalradionuclides from the raw process water, as shown in
Table 10. No quantitative information on the actual
discharges appears to be available to the Committee.
44. In the thermal process normally used for highgrade acid and phosphates, coke and silica are added to114

phosphate rock in an electric furnace. The chemical
reaction at high temperature produces elemental
phosphorus, which is relatively free of radioactivity,and several by-products among which calcium silicateslag, which carries the bulk of the activity initiallycontained in the phosphate rock, and ferrophosphorus
are the most important (B4, 04, M14]. The smelting of
the ore results in 210110 and other volatile radioactive
material releases [IJ4]. Actual airborne discharges are
not available.

3.

Effluents from uranium reco,·cry operations

45. Various processes have been suggested forrecovering uranium from phosphate rock [R2, R3]. The
plants already existing or being designed forconstruction in central Florida employ solvent
extracdon of uranium from phosphoric acid produced
at a new process phosphoric acid plant [D2].
46. Annual airborne discharges (Table 10) from acommercial uranium recovery plant in Florida havebeen estimated to be about 400 I\1Bq of 238U on thebasis of limited measurements [D2]. The major contribution to atmospheric radioactive releases was foundto occur in the drumming building; the material
released was uranium with natural isotopic composition. The production rate of the plant was about 50
tonnes of uranium per year, corresponding to approximately 4 ]05 tonnes of marketable phosphate rock.

4.

Emironmental concentrations and doses

47. As the heights of atmospheric releases are in
general less than 50 m above ground level, surface air
measurements in the vicinity of the plants usually show
the presence of enhanced concentrations of naturalradionuclides.
48.
Air activity concentrations of mu, 226Ra, and"30Th were found to be about 200 µBq m-3 at approximately 400 m from the ore drying plant investigated[P4]. In comparison. the average background activity
concentrations in the area are about 15 µBq m-3.
49. Smaller increases were observed around the two
wet process phosphoric acid plants. Average concentrations of about 30 µBq m-3 of mu. 226Ra, and 230Tb
were measured at approximately 1000 m from theplants [P4].
50. In Idaho, at about 800 m downwind from two
adjacent phosphate plants, a wet process plant and athermal process plant, the annual average gross alphasurface air activity concentration was about 700 µBq
m-3 in 1974 [84]. Most of this activity is attributed to:1opo.
51. The main pathways through which the populations living around those plants are exposed to,enhanced levels of natural radionuclides are inhalation
during the passage of the cloud, and external irradiation, inhalation and ingestion resulting from theactivity deposited on the ground. The collective dose
commitments corresponding to those pathways havebeen roughly estimated using the methods alreadydescribed in paragraphs 24-28 for airborne discharges
from coal-fired power plants.

52. The collective dose commitments due to inhalation of all radionuclides except 222Rn and its short-lived
decay products are expressed in the form
(5)
where Ao is the annual release (Bq); B is the breathing
rate. taken to be equal to 2.3 1~ m3 s-t for an adult;
Vd = 10-2 m s-1; 6N, the human population density, isassumed to be uniform and equal to 100 km-2 aroundthe plant: Dq/l;h is the committed absorbed dose inorgan or tissue q per unit intake (Gy I3q-l). The values
adopted for Dq/hh are those of Table 5, related toemissions from coal-fired power plants.
53. Regarding inhalation of 222Rn and its short-lived
decay products, the expression used iswhere Ao is the activity of 222Rn daughters associatedwith the release of 222Rn (the equilibrium factor
between 222Rn and its daughters is taken to be 0.6).
54. The estimated collective dose commitments due toinhalation during the passage of the cloud arepresented in Table 12 for some of the radionuclides
discharged into the atmosphere as a consequence ofprocessing one tonne of phosphate ore. The radionuclides considered are those for which discharge data
have been measured or derived from measurements (seeTable 10 and paragraphs 39. 42 and 46).
55. The collective dose commitments incurred after
deposition (external irradiation and internal irradiation
arising from inhalation of resuspended or emanatedmaterial and ingestion of contaminated foodstuffs) can
be roughly evaluated by comparison with the naturalsoil activity concentrations and the corresponding dose
rates. As in the case of the airborne discharges fromcoal-fired power plants (see paragraphs 26 and 27), theexpression used is(7)

where Ao is the activity associated with the release of agiven radionuclide; Dq is the natural dose rate in organor tissue q due to the radionuclide under consideration;'t is the mean life of the long-Jived natural radionuclides
in soil. taken to be 100 years; h is the thickness of soil
involved, expressed as mass per unit area (assumed to
be 500 kg m-2); and C is the natural concentration of
the nuclide in the soil. The collective dose commitments
per unit mass of marketable ore processed obtained inthis way are presented in Table 13.

B.

DOSES ARISING FROM THE USE OFPHOSPHATE FERTILIZERS

56. The world production of phosphate fertilizers wasapproximately 3 1010 kg of P20s in 1977 [Ul]. Assumingthat the activity distribution given in Table 11 holds ona global basis, the mass of marketable rock necessary to
produce such an amount of phosphate fertilizers was
about lQll kg, which is approximately three-quarters of
the world production of marketable ore in that year
(1.3 1011 kg).

57. The application rate of fertilizers depends interalia on the type of soil and on the type of crop. The
average consumption of phosphate fertilizer per hectareof agricultural land varied in 1977 from 0.9 kg P20s for
the African continent to 37.6 kg P205 for Europe, theworld average being 6.3 kg P20s [F3]. The amounts offertilizer applied annually by crop in the United States
have been reported to range from about 30 kg P20s per
hectare for barley, wheat and oats to about 150 kg P20s
per hectare for potatoes and tobacco [N4].
58. Measured activity concentrations of naturallyoccurring radionuclides in phosphate fertilizers fromseveral countries are summarized in Table 14. With the
exception of basic slag (a by-product ·or the
manufacture of steel), all the fertilizers considered inTable 14 are derived from phosphate ore processing.
For a given radionuclide and type of fertilizer. theconcenti;ations vary markedly from one country to theother. depending on the origin of the components.
Relatively high concentrations of 238U are observed orshould be expected when the phosphate ore is of
sedimentary origin, while low concentrations areassociated with ore of magmatic origin.
59. The degree of radioactive equilibrium between
238U and its decay products depends on the type of
manufacturing process used and more specifically on
the relative contribution of phosphoric acid in the endproduct, since phosphoric acid has usually a very low
content of 226Ra. The lack of equilibrium between 238U
and 226Ra is particularly clear for triple superphosphates and ammonium phosphates. Other generalfeatures that can be observed in Table 14 are that theconcentrations of 232Th are always low; with the
exception of the potassium fertilizers, the concentrations of potassium (and thus 40K) are also generally
low; that the concentrations of 226Ra do not exceed
1000 Bq kg-I; and that 21opb and 210po are generally
close to radioactive equilibrium with 226Ra.
60. Phosphate fertilizers contribute to the externalradiation exposure of persons occupationally handling
phosphates and of members of the public. Through thecontamination of foodstuffs, they also contribute tointernal irradiation of mankind.
61. Pfister and Pauly [P7] have estimated the externalradiation exposure of members of the public and of thesmall group of persons working in production,transport, storage and application of rock phosphates
and phosphate fertilizers in the Federal Republic of
Germany. With regard to the dispersal of phosphate
fertilizers in agricultural areas. they assessed theaverage addition to the soil activity in 1977-1978 at 17
Bq m-2 of 238U. 11 Bq m-2 of 226Ra. 7.4 Bq m-2 of 232Th
and 150 Bq m-2 of 40K. Assuming an accumulation of:26Ra in the soil during the last 80 years, a mean
additional absorbed dose rate in air of about 8 1(}-4 µGy
h-t was calculated. Fertilizer application therefore
results in a fairly small increase of the externalradiation exposure over natural background which, on
average, is 0.05 µGy h-1 (see Annex B). In contrast, theoccupational radiation exposure of individuals can bemuch higher. Pfister and Pauly [P7] measured mean
additional absorbed dose rates in air ranging from 0.02
to 0.23 µGy h-1 for various transport and loading operations and peak values of 0.8 µGy h-t. In agricultural
storehouses. they measured a mean additional absorbed
dose rate in air of 0.09 µGy h-1. It is possible. however,that inhalation of fertilizer dust might lead to higher
doses.
115

62. A slight increase in the concentrations of naturalradionuclides of the mu series is also expected tooccur in food crops grown on soils supplied with highamounts of phosphate fertilizers. Kirchmann et al. [KS]measured the 226Ra activity concentration in straw andgrain of wheat harvested in plots fertilized for 11 years
with controlled amounts of phosphate fertilizers. There
was no significant difference in the 226Ra concentrations of wheat harvested in the plots fertilized at highlevels (1356 kg P20s per hectare) or at low levels (343 kg
P~Os per hectare). However, the '.'26Ra soil contamination resulting from the application of phosphate fertilizers represented respectively only 1.08% and 0.25% of
226Ra activity of natural origin observed in the upper
layer of soil [KS]. The small relative contribution of the
226Ra content in the fertilizer to the natural 226Ra
content in the soil, combined with the fact that the fertilizer was homogeneously mixed in the soil, is likely tohave precluded experimental evidence of an increased
226Ra concentration in wheat. Other tests with fertilizers
labelled with 226Ra have shown that the radionuclide
uptake by plants is practically the same whether it isincluded in fertilizer or in soil structures [DSJ.
63. However, foodstuffs may be contaminated to agreater extent if, for example, fertilizers are applied inliquid form on the soil surface or if phosphate products
are used to feed animals. Phosphate products are extensively used as a source of phosphorus in livestock feed
supplements. Activity concentrations of 226Ra inlivestock feed supplements have been measured in the
United States to range from 7 to 1600 Bq kg-1 [RSJ,
which is consistent with the values presented inTable 14 for phosphate fertilizers. An assessment of thetransfer to milk of 226Ra ingested by dairy cows in theirfeed supplements showed that the maximum 226Ra
concentration in milk would be about 25 Bq m-3, to becompared with ··normal" concentrations of 3 to 10 Bq
m-3 [RSJ.
64. The collective dose commitments arising from thedecision to use one tonne of marketable ore to produce
phosphate fertilizer can be crudely estimated with themethod used in paragraph 55. According to the data
presented in Table 11, one tonne of marketable rockproduces 0.54 tonne of fertilizer. On the basis of theresults presented in Table 14, the average activity
concentrations of natural radionuclides in phosphate
fertilizers are taken to be 600 Bq kg-I for 238U, 234U and
230Th, and 400 Bq kg-I for 226Ra and for each of its
decay products. Therefore, one tonne of marketable ore
is estimated to produce 0.54 tonne of phosphate fertilizers containing about 3 105 Bq of 238U and 2 105 Bq of
226Ra and of each of its decay products. The activity
concentrations of 40K and of the radionuclides of the232Th series are generally low and the corresponding
doses have been neglected.
65. Assuming that the ploughed layer of soil is 30 cm
deep; the availability to plants of natural radionuclides
is the same whether in fertilizer or in the normal constituents of the soil; the deposited activity becomes
unavailable to the vegetation with a mean life of 100
years for the long-lived natural radionuclides; and thefraction of time spent by the populations exposed on,or near. fertilized fields is 1% ; then the collective dose
commitments per unit mass of marketable rock arisingfrom external irradiation and from internal irradiation(resuspension and emanation from soil and ingestion ofcontaminated foo_dstuffs) may be calculated as in
Table 15.
116

C.

DOSES ARISING FROM THE USE OF
BY-PRODUCTS AND WASTES

66. The main by-products resulting from processing
phosphate ore in phosphoric acid plants are gypsum (orphosphogypsum) in wet process plants and calcium
silicate slag in the thermal process plants. Radiation
exposure to members of the public can occur if thoseby-products are used in the building industry. Anothersource of exposure stems from the reclamation of landon which phosphate mining has been completed andhouses have been allowed to be built.
67. Large quantities of phosphogypsum are producedin the wet process phosphoric acid plants. The annual
world production of phosphogypsum was approximately 9 1010 kg in 1974, which is greater than the
production of natural gypsum [F4]. As shown in Table
11, the mass of phosphogypsum produced is about thesame as that of the phosphate ore processed and thebulk of the 226Ra content of the phosphate ore is transferred to phosphogypsum. The average activity concentration of 226Ra in phosphogypsum was taken to beabout 900 Bq kg-I in Annex B of the 1977 report [U2].
68. Phosphogypsum can replace natural gypsum inthe building industry and thus be used to make blocks
and plaster board, partition systems and also cement[NS, 02, 03]. The practice of using this waste producthas been considered attractive, since overall building
costs are reduced, natural resources are preserved. andenvironmental pollution is decreased. On the other
hand, since phosphogypsum contains a much higher
concentration of 226Ra than its natural counterpart, its
use increases the radiation doses to the public.
69. Japan was the first country to employ phosphogypsum for construction purposes in 1934 [S4]. In 1974,
approximately 3 109 kg of phosphogypsum was used inJapan in the construction industry, half of it as setting
controller for cement. The use of phosphogypsum forplaster, plasterboard and building blocks has gained
importance throughout the world [S4].
70. O'Riordan et al. [U2] estimated the additionaldoses that would be received by the occupants of aresidential building in which 4.2 tonnes of by-productgypsum (considered to be a high, but realistic amount)would have replaced the established materials.
Assuming the 226Ra concentration of phosphogypsum
to be 900 Bq kg-1, they estimated the additional
absorbed dose rate in air to be 0.07 µGy h-t, and the
additional radon concentration, using a ventilation rateof 1 h-1, to be about 10 Bq m-3.
71. If it is assumed that all the phosphogypsum
produced by 1 tonne of marketable ore is used in thebuilding industry, that on the average four persons livein the dwellings so constructed, and that the mean lifeof the dwelling is 50 a, the whole-body collective dose
commitments due to external irradiation can beevaluated from the estimates provided by O'Riordan etal. [02], to be about 0.02 man Gy 1-1. Assuming that theequilibrium factor between radon and its short-lived
decay products is 0.6, the collective effective dose
equivalent commitments arising from indoor inhalation
would also be about 0.02 man Sv t-1.
72. It should be indicated that phosphogypsum is also
used in agriculture as an amendment to improve water
movement in saline-alkaline soils and may also be
substituted for limestone or lime to supply calcium toalkaline soils [L3]. Owing to the low solubility of
Ra Sp4 and to the effect of the presence of calcium, the22°Ra soil-plant transfer coefficient for plants grown on
phosphogypsum-treated soils should be smaller thanunder "normal" conditions [L3].
73. Calcium silicate slag is a by-product of phosphateore processing by the thermal process. With the
exception of 210Po, which is driven off during smelting.
the measured concentrations of the natural radionuclides of the 238U series were found to be about thesame in the phosphate ore and in the slag [B4, G4, PS].
74. In Idaho. about 2.4 109 kg of slag are produced
each year [84]. Measured activity concentrations in slag
samples are 1300-1500 8q kg-1 of 226Ra. 740 Bq kg-I of230Th and 1000 Bq kg-I of 238U. About one-tenth of thisproduct is sold to slag crushing operations that market
the material for railroad ballast, asphalt, concrete, andother uses. In that way. about 800 G8q of 226Ra wasdistributed into the environment in the areas ofPocatello and Soda Springs in 1974. The number ofstructures and dwellings constructed with slag inconcrete is estimated to be approximately 150. Gamma
surveys were conducted in Soda Springs and Pocatello.
Above asphalt containing slag, the average external
gamma absorbed dose rate in air was found to be about
0.08 µGy h-1 above background, the maximum level
being approximately 0.3 µGy h-1. The preliminary resultsfrom the indoor survey indicate that the gamma
absorbed dose rate in air can also be as high as 0.3 µGy
h-1 above background in dwellings constructed with
43% by weight slags in concrete slabs [84). In
comparison, the average gamma absorbed dose rate in
air received indoors is estimated as 0.06 µGy h-1 inAnnex 8.

reclaimed to various degrees. It is estimated that 4000
structures may be built on phosphate lands in central
Florida [R6]. Absorbed dose rates in air were measured
in and out of 672 structures built on reclaimed land.
The average absorbed dose rate in air was found to be
0.092 µGy h-1 outdoors, the highest one 0.35 µGy h-1[G7. GS]. By comparison, the natural backgroundoutside the phosphate area is approximately 0.05 µGyh-1. The indoor levels reflected the degree of floor
shielding present in the various structure categories.
Absorbed dose rates in air in excess of 0.17 µGy h-1
were only observed in crawl space and trailer constructions. which have either wood or thin metal flooring[G7]. The equilibrium equivalent radon concentration
in houses ranged from 4 to 500 Bq m-3 with a weighted
average of about 40 Bq m-3 which is estimated to be 26
Bq m-3 above normal concentrations in houses of thatarea. This average additional concentration results inan annual effective dose equivalent of approximately
1.6 mSv.

D.

RECAPITULATION

78. Table 16 summarizes the radiation exposures dueto the exploitation of phosphate rock, expressed interms of collective effective dose equivalent commitments resulting from the decision of using a unit massof marketable ore to accomplish a defined purpose. The
most important natural radionuclides have been taken
into account.
79. The impact from one year of phosphate oreprocessing has been very crudely estimated on the basisof the following data and assumptions:(a)75. In Canada, about 21 OOO tonnes of slag arisingfrom a thermal process plant using Florida phosphaterock as input feed has been crushed and used inroadbeds, laneways, backfill around basements, and asa base for concrete floors in basements of dwellings[M14]. Measurements of slag samples indicated a 226Ra
activity concentration of 2150 Bq kg-I. A gamma survey
was conducted inside homes with slag and without slag.
For 24 dwellings with slag, the average absorbed dose
rate in air was 0.12 µGy h-1 with a standard deviation of
0.04 µGy h-1. The range of values observed was 0.07 to
0.21 µGy h-1 (excluding two houses in which crushedslag had been spread over the basement excavation toform an unfinished floor, resulting in measured
absorbed dose rates in air of 0.33 and 0.54 µGy h-1,
respectively). By comparison, the average absorbed
dose rate in air for 54 homes without slag was 0.09 µGyh-1, with a standard deviation of 0.02 µGy h-1 and arange of 0.05 to 1.5 µGy h-1. Thus the use of slag has led
to an apparent increase of 0.033 µGy h-1. Thisdifference is, however, not statistically significant
because of the standard deviations given above [M14].

The world production of marketable rock is
1.3 1011 kg in a typical year;(b) All the marketable ore is processed in ore drying
plants;(c) Seventy per cent of the marketable ore production
is used to prepare phosphate fertilizers;(d) With regard to the wet process phosphoric acidplant, the results relative to plant A (see Tables 12
and 13. and paragraph 42) are adopted;(e) Ten per cent of the by-product gypsum is used asbuilding material in dwellings.
80. On the basis of these assumptions, the collective
effective dose equivalent commitment resulting fromthe 1977 production of phosphate rock is estimated to
be about 3 105 man Sv; by far, the most important
contribution to the total dose is due to the use of byproduct gypsum in dwellings. The total of the othercontributions to the collective effective dose equivalentcommitment is only about 6000 man Sv.

IV.
76. A similar situation has been discovered to occur in
Florida [A2]. Approximately 250 OOO tonnes of slag areused each year for paving roads, as ballast, as material
for railroad beds, and for house roofing material. An
investigation was conducted by the United States
Environmental Protection Agency [A2].
77. Residents in structures built on "reclaimed"
Florida phosphate land may also be exposed toenhanced radiation doses. About 600 km2 of Florida
land have been mined for phosphate rock in the last 80
years. Of that amount. about 200 km2 have been

ENHANCED INDOOR EXPOSURES

81. Indoor exposures result mainly from external
irradiation and from inhalation of radon decay
products. The general aspects of indoor exposures are
discussed in Annexes B and D. This section deals essentially with elevated indoor exposures. High external
irradiation rates usually arise from high concentrationsof natural radionuclides (especially 226Ra) in building
materials and in soil. Elevated concentrations of radon
decay products may be due to the same reasons or tohigh radon influx from the soil. or to high radon
concentrations in water or natural gas used in homes.
11782. Building materials. As exemplified in Table 17, theuse of some building materials may lead to elevatedindoor radiation levels. The building materials may beof natural origin, such as pumice stone (Federal
Republic of Germany and the USSR), concrete
containing alum shale (Sweden), lithoid tuff (Italy), andgranite wherever it is used. They may also result fromindustrial processes. ln the non-uranium industries. theuse of phosphogypsum and of calcium silicate slag, two
by-products of the phosphate industry have alreadybeen discussed. Other by-products that were shown tocontain relatively high concentrations of naturallyoccurring radionuclides were red mud, a waste productof aluminium mills, and blast furnace slag, a byproduct of iron manufacture [K7].
83. In its basic radiation standards. the National
Commission of Radiation Protection of the USSR [K8]used a dosimetric relationship. If the concentrations of
40K, 226Ra and 232Th, expressed in Bq kg-I, in materials
made of industrial wastes satisfy the expression
C (4oK)
4810---+

C (226Ra)
C (232Th)
+
~l
370
259

(8)

it was estimated that the increase over background of
the gonad absorbed dose indoors from external irradiation is less than 1.5 mGy in a year. In comparison, theaverage absorbed dose in all tissues received indoors
from external irradiation of terrestrial origin is assessed
as 0.3 mGy in a year in Annex B. The measurements ofactivity concentrations of naturally-occurring radionuclides in building materials in the Soviet Union [K8]
showed that only a few materials would not satisfy theexpression given above, while in the Federal Republicof Germany it was found that 12% of the analysedsamples would exceed that limit [K7].
84. It should be pointed out that the average absorbed
dose rates in air measured in buildings using thesematerials are much lower than what would be expectedfrom the radioactive content of the materials
considered, because materials usually less active arealso used in the same buildings. For example, theaverage absorbed dose rate derived from measurements
carried out in Swedish houses made of aerated concrete
containing alum shale is about 0.17 µGy h-t [M7]. whilethe value given in Table 17, calculated from the activity
concentration of radionuclides in that type of concrete.
using very pessimistic assumptions, is 1.5 µGy h-1 [S6].
Measurements of radon daughters have been carriedout in 32 single-family houses containing a large
fraction of concrete based on alum shale in theirbuilding materials [S13]. The average equilibrium equivalent concentration of radon in those houses was foundto be 260 Bq m-3, corresponding to annual effective
dose equivalents of 16 mSv.
85. Waste products of the uranium and radiumindustry have been used as building materials. In the
United States, notably in Grand Junction, Colorado.
tailings from uranium mills were used during the period
1952-1966 as fill material under houses and as building
materials [U4]. Remedial action was deemed necessary
by the national authorities more because of the elevatedradon concentrations measured in houses than becauseof the external radiation doses. The average equilibrium
equivalent concentration of radon measured in 47
houses was about 200 Bq m-3 [C7]. It is in many cases
true that when building materials containing highconcentrations of 226Ra are used in dwellings, theoccupants receive a higher effective dose equivalent
118

rate from inhalation of 222Rn and its short-lived decay
products than from external irradiation.
86. In the town of Port Hope, Ontario, Canada.
another type of problem arose from a plant which had
recovered radium in the 1930s and the 1940s frompitchblend-radium-silver ores [S7]. In this particularcase, the potential radon problem was not recognized
and consequently much contaminated construction andfill material was used in and around the houses in thetown. As in the case of Grand Junction, remedial action
was deemed necessary by the national authorities.
87. Radi11111 in soil. In Sweden, areas containing
tailings from the alum shale industry have been built
on. The radium concentration of the tailings is on
average 2900 Bq kg-1 and the outdoor gamma radiationdose rate in air is of the order of 1 µGy h-t [S14]. In
houses,. the equilibrium equivalent concentration ofradon was found to be 500 Bq m-3 on average [S14],
corresponding to annual effective dose equivalents ofabout 30 mSv. In March Township. Ontario, Canada,
343 houses were surveyed because of the discovery of
nearby low-grade uranium deposits. The highest
equilibrium equivalent concentration of radon was 700
Bq m-3 and the weighted arithmetic average 50 Bq m-3[LS]. This weighted average is estimated to result inannual effective dose equivalents of 3 mSv received
indoors.
88. High radon i1iflux from soil. In the Chicago area,
United States, high radon concentrations have beenfound in houses with unpaved crawl spaces while theradium concentration in soil was normal [R9]. In a totalof 22 houses investigated, the radon concentration was
more than 185 Bq m-3 in nine houses and more than 370
Bq m-3 in six of these. Most of the radon emanatedfrom the unpaved crawl space under the house. In
Sweden, it is estimated that about 75% of the totalcollective dose caused by inhalation of radon daughtersarises from radon emanating from the ground. Houses
have been found with more than 10 OOO Bq m-3 ofradon. An equilibrium equivalent concentration ofradon of 10 OOO Bq m-3 is estimated to yield an annual
effective dose equivalent of about 600 mSv received
indoors.
89. Radon in water. Radon in water may be a significant source of radon in the air in dwellings in many
countries. In the region of Helsinki, Finland, very highconcentrations of radon in water from deep wells.
ranging up to 44 MBq m-3, have been reported [C8].
From measurements of air concentration of radon in 20
houses [A5J, it can be derived that the average
equilibrium equivalent concentration of radon would
be 360 Bq m-3 with a maximum value of 1200 Bq m-3.
In Canada, the area of Castlegar-Trail in British
Columbia, was surveyed because of high radon concentrations in water. The weighted average equilibrium
equivalent concentration of radon in indoor air was
found to be about 70 Bq m-3 while the highest value was2900 Bq m-3 [L5].
90. Radon in gas. Natural gas containing radon may
also be a significant source of radon in indoor air if it isused in unvented appliances. Average radon concentration in natural gas in various distribution lines havebeen reported to be within the range of 40 to 2000 Bq
m-3 [J9, W9]. Assuming that natural gas is used inunvented kitchen ranges, the resulting additional
indoor air concentrations are estimated to be only
about 0.01 to 0.3 Bq m-3,

91. In conclusion, enhanced indoor exposures may be
due to various reasons and may give rise to highindividual doses. More detailed information on theelevated indoor concentrations of radon that have beenmeasured in several countries is provided in Annex D.
The collective doses have not been quantified owing to
the lack of data on the number of houses involved.
Further measurements arc required in that field.

V.

ENHANCED EXPOSURES TO COSMICRAYS
A.

PASSENGERS IN AIRCRAFT

92. The number of passenger kilometres flown
throughout the world in scheduled commercial flights
was 9.34 1011 in 1978 [12). Taking the average speed to
be 600 km h-1, a total of about 1.6 109 passenger hours
was spent travelling in that year. The dose rates
incurred during the flights vary according to thealtitude and, to a smaller extent. to the latitude and to
the solar activity. Table 18 shows the variation withaltitude. from 4 to 20 km. of the dose rate and of thedose equivalent rate averaged over two geomagnetic
latitudes and two periods of solar activity (04). The
altitudes of subsonic flights depend on the type of
aircraft used and on the distances covered in a given
flight. They could be as low as 2-3 km for short flights
and as high as 12 km for intercontinental flights. withintermediate values of 5-10 km for medium-range andcontinental flights [1-12. Wl, W2]. Table 18 shows thatthe dose rate and the dose equivalent rate vary by afactor of 20 between the altitudes of 4 and 12 km.
Assuming that the average altitude of commercial
flights is 8 km, the average dose rate would be 0.84 µGy
h-1 and the average dose equivalent rate 1.35 µSv h-1.
yielding a collective effective dose equivalent to theworld population of about 2000 man Sv from air transportation in 1978.
93. Supersonic aircraft (SST). which are used on asmall scale. fly at altitudes ranging up to 20 km,
compared with at most 12 km for standard jet aircraft.
Assuming that SSTs fly at an average altitude of 16 km,
the average absorbed dose rate would be about 6 µGy
h-1 (Table 18). Actually, the absorbed dose rates
measured on board the commercial SST flights of Air
France. averaged over the years 1976-1980, amount toabout 5 µGy h-1 [PS). Taking from Table 18 the quotientof the dose equivalent to the absorbed dose to be 1.6 Sv
Gy-1, the corresponding dose equivalent rate is about
8 µSv h-t.
94. Wallace [W2) calculated absorbed doses topassengers for a round trip, for both subsonic andsupersonic transport between various city pairs. Someof these estimates are shown in Table 19. Doses for around trip in supersonic aircraft are approximately 70%of those for subsonic speeds. because of the shorter
flying time. However, the dose rates in supersonicaircraft are about twice as high as in subsonic aircraft.
For a round trip across the Atlantic. the tissue absorbed
doses in passengers may be estimated to be about 2 10-s
Gy for an SST and 3 1o-s Gy for a subsonic aircraft,under average solar conditions.
95. All the dose values given above refer to galactic
cosmic rays. There is, in addition. a contribution due tothe solar flares. From dose rate values given in the 1972
UNSCEAR report [U6], based on results obtained by

an ICRP working group by averaging the effects ofsolar flares over the period 1952-1960 [13], the averageabsorbed dose index rates from solar radiation can be
estimated to be 4 I 0-8 Gy h-1 at 12 km and 9 10-7 Gy h-1
at 20 km. The average contribution from this source isthus small compared with that from galactic cosmic
rays.
96. Although radiation of solar ongm does notcontribute significantly to the average absorbed doseindex rate, during an occasional intense solar flareradiation levels at these altitudes may increase by
several orders of magnitude. The giant solar flare
events last only for about 10 h and occur a few times ineach solar cycle, and therefore are not likely to add
significantly to the collective dose of the world
population. It is worth mentioning that SST aircraft
carry radiation monitors. and the pilots will move theaircraft to lower altitudes when the dose rate reaches aprescribed level.

B.

ASTRONAUTS

97. When travelling into space. astronauts are
subjected to primary cosmic ray particles. the radiationfrom solar flares, and also the intense radiation present
in the two radiation belts. Savun et al. [SS] havereported measurements in the radiation belts in 1971.
Measurements inside a 0.7 g cm-2 shield indicate thatthe maximum absorbed dose rate crossing the inner belt
was 0.22 Gy h-1 and crossing the outer belt 0.054 Gy h-1.
98. Estimated absorbed doses received by astronauts
on several Apollo missions (average for the threeoccupants) based upon measurements carried out withtissue-equivalent ionization chambers are shown in
Table 20 [C3, E2, R7, G9]. A large part of this dose wasreceived while the spacecraft was passing through theearth's radiation belts. For example. the higher dose
received on the Apollo X mission was largely due to adifferent trajectory through the radiation belts.
Analogous data in Table 20 from space flights of the
USSR (Vostok. Voskhad and Soyuz series) indicate
doses of comparable magnitude [G9). Table 21 indicatesthe breakdown of the absorbed dose and of the dose
equivalent on the first lunar landing mission, Apollo XI[E2].
99. In outer space, remote from the shielding
influence of the earth's magnetic field. the absorbed
dose index rate from solar protons emitted during solar
flares can be very high. For example. it has been
estimated that the absorbed dose indices in outer spacefrom the solar proton event of 10 July 1959 were: fromprotons 3.6, 1.7, and 0.4 Gy behind shielding of 1. 2 and5 g cm-2, respectively, and from alpha particles thecorresponding values were 1.5. 0.3 and 0.05 Gy, respectively [C3). However, the Apollo missions did notexperience any measurable solar particle events [E2].

VI.

MISCELLANEOUS SOURCES OFRADIATION

100. In the present context the term miscellaneous
sources indicates a variety of radiation sources which
the general public is exposed to during the normal
course of its activities, generally without being aware ofthem. Those sources of radiation result from man-made119activities. Most of them are consumer products
containing radioactive substances that have been deliberately incorporated to satisfy a specific purpose.

A.

CONSUMER PRODUCTS

101. The consumer products containing deliberately
incorporated radionuclides can be broadly classified
into five categories: radioluminous products; electronicand electrical devices; antistatic devices; smoke
detectors; and ceramic. glassware, alloys, etc.
containing uranium or thorium. Some of theseproducts, such as the antistatic devices, are more widely
disseminated in industry than among the generalpublic.
102. Table 22 presents some information on thenumber of products and the activities involved in eachcategory in the Federal Republic of Germany [W3].
Although the data shown are not contemporaneous assome correspond to the year 1973 and others to the year
1975, the table gives a good idea of the relative importance of each category in an industrialized country.

I.

Radioluminous products

103. Radium-226, promethium-147, and tritium havebeen used extensively in the dial-painting industry forthe illumination of timepieces, the radiation emitted bythose radionuclides being converted into light by ascintillator, which is usually zinc sulphide containing
small amounts of copper or silver. From the publichealth point of view, one of the major disadvantages ofradium is its inherent emission of a great deal of
penetrating radiation which is not useful for the
production of light yet irradiates the whole body of thewatch wearer. Radium tends to be replaced by 3H and
147Pm, which are soft beta emitters and thus cause muchsmaller external radiation doses to the watch users.
104. Table 23 presents estimates of the numbers ofradioluminous watches and clocks in use in
Switzerland, the United Kingdom and the UnitedStates. The values for the United States are based on
production data assuming that the average useful life of
a luminous timepiece is 3 years [M8]. The estimatesfrom Switzerland are an extrapolation to the whole
population of the country of the results of a survey
involving 1032 consumers [K9]. The data for the United
Kingdom are based on information from the watch
trade [Tl]. It is clear from the table that most of theradioluminous watches contain tritium; in clocks,
147Pm and 226Ra seem to be more used than 3H.
105.
The activities of 3H and 147Pm which produce
the same brightness as 37 kBq of 226Ra have been
estimated to be about 200 TUq of 3H and 6 TBq of
147Pm for a newly manufactured timepiece [14].
However, owing to radio.ictive decay, release of activity
and deterioration of the phosphor, the brightness
decreases continuously over the useful life of the
timepiece at a rate that depends upon the radionuclideused. The activities of 3H and t47Pm required to
produce the same average brightness as 37 kBq of226Ra
over the useful life of the timepiece, taken to be three
years, have been estimated to be about 300 TBq of 3H
and 10 TBq of 147Pm [M9].
120

(a)

Absorbed doses from 226Ra-actfrated timepieces

106. The absorbed doses from 226Ra-activatedtimepieces result mainly from external irradiation, therelease of radon being usually insignificant. As
indicated in Annex B of the 1977 report [U2], an annual
gonad dose per unit activity of 1.6 10-s Gy Bq-t isestimated for wrist-watches worn continuously.
According lo the recommendations issued by a joint
group of experts from OECD and IAEA (14), the total
activity of 226Ra should be limited to 3.7 kBq. That limit
corresponds to a gonad absorbed dose in a year of 40µGy if the watch is worn on average 16 hours per day.
However, as the production of 226Ra-luminous watches
has stopped in many countries, a significant fraction of
the existing 226Ra-painted watches is likely to have been
manufactured in the 1950s or the early 1960s, and tocontain greater activities than the limit.
107. The external radiation gonad dose per unit
activity to the user of an alarm clock has been calculated for an exposure of 8 h per day at a distance of 2 m
to be 1.6 10-10 Gy Bq-1 [M8]. Assuming that the 226Ra
activity contained in the alarm clock is 5.5 kBq, whichis the limit recommended [14], the annual gonad dosewould be about 1 µGy; the annual effective dose equivalent would be about 1 µSv.

(b) Absorbed doses from JN-activated timepieces
108. As shown in Table 22, most of the radioluminous
watches currently in use are luminized with tritium
paint. The external dose from a tritium luminous watch
is negligible because of the low energy of the ~-particles
and of the bremsstrahlung arising from the decay of 3H.
However, tritiated water or tritiated organic molecules
evolve slowly from the tritium paints leading to internal
absorbed doses to wearers from inhalation and skinabsorption.
109. The relationship between the 3H act1v1ty inwatches and the resulting whole-body absorbed dose
has been studied under controlled conditions by
Moghissi and Carter [M9]. The average dose in a year
per unit activity of tritium paint, from a watch worncontinuously, was found to be 8 10-1s Gy Bq-1, therange being 3 10-1s to 1.2 10-14 Gy Bq-1.
110. There are as yet no published estimates of doses
from 3H-activated alarm clocks. The activity-to-dose
relationship has been conservatively assumed to be thesame as that adopted for watches. Taking into accountthe fact that the exposure occurs only 8 hours per day
on average, the quotient of annual dose to activity
would be about 3 10-1s Gy Bq-1 for alarm clocks.
111. The average content of tritium in luminous
timepieces has been determined in Switzerland to be 37
MBq for wrist-watches and 60 MBq for clocks [K9]. In
the United States, the records from the Nuclear
Regulatory Commission suggest an average of 25 MBq
for watches and 15 MBq for clocks [MS]. In this Annex,
a single value of 40 MBq will be adopted for the
purpose of dose calculations. It results in a whole-bodydose of 0.3 ~LGy for the wearer of a tritium-painted
watch. and of 0.1 µGy for the user of a tritium-painted
clock. The corresponding annual effective dose equivalents would be 0.3 µSv and 0.1 µSv, respectively.
112. With the advent of liquid-crystal displays, the useof gaseous tritium light sources (GTLS) to illuminatedigital watches could l;>ecome widespread in the near
future. A GTLS consists of a hollow glass tube whose
inside walls are coated with an inorganic phosphor. The
tube is evacuated. back-filled with tritium gas, and laser
sealed. For watch applications. the tritium conl~nl ismuch higher than in a painted watch; it was observed
to range from 1.7 GBq to 7.4 GBq [W4]. A total of
approximately 40 OOO timepieces were distributed
during 1976 in the United States [R8]. Preliminary tests
indicate that the dose lo the wearer will result fromtritium permeating through the glass and being
absorbed into the body [W4]. It appears al present thaton average the dose to the wearer of a watch luminizedwith a GTLS containing 7.4 GBq of 3H may be of thesame order as that to the wearer of a typical watch
luminized with 3H paint [Tl]. There will also be internal
dose to a person breaking the source which is usually
sealed in a metal or glass capsule with the liquid-crystal
display and is not easily accessible to the wearer. Out of
the 40 OOO timepieces distributed in 1976 in the UnitedStates, two watches were returned for tritium tube
breakage [R8]; thus only a small fraction of the tritiumis returned to the environment.

Kingdom, and the United States, respectively. Translated into per caput annual effective dose equivalent,
they become 8 10-7. 6 10-7, and 8 lQ-3 Sv. The per caput
annual effective dose equivalent for the United States ,population is underestimated because the 226Ra-painted
watches were assumed to be completely out of use.
Taking an average value of 5 10-7 Sv to be representative of the per caput annual effective dose equivalent
to the world population, the annual collective effective
dose equivalent for the world population is found to beof the order of 2000 man Sv.

(e)116. It is known that radioluminous materials arebeing used in exit signs. compasses, gun sights,
telephone dials, and many other devices, but there is
not enough information available to make a reasonableestimate of the doses arising from their use. However, it
is likely that the resulting collective dose is insignificant
in comparison to that from radioluminous timepieces.

2.

(c)

Electronic and electrical devices

Absorbed doses from U7Pm-activated timepieces

113. Since promethium is a solid, it does not evolvefrom a watch under normal conditions of usage, so thatthe risk of external radiation is the only one that has tobe considered. Promethium-147 is a pure beta emitter.
The maximum energy of its beta particles is 224 keV,corresponding to a range of 46 mg cm-2. Since thestandards set by the OECD and the IAEA recommend
a minimum thickness of 50 mg cm-2 for the casing of
timepieces, no exposure hazard from beta radiation
should exist. However. a low external radiation dosefrom bremsstrahlung has to be expected. Moghissi andCarter [M9] have conservatively estimated the annual
gonad dose per unit activity to be 1.410-12 Gy Bq-1. The
average J47Pm content of timepieces is suggested to be
1.5 MBq on the basis of a search of the records of theUnited States Nuclear Regulatory Commission. The
resulting gonad dose to the wearer of a 147Pm-painted
watch would be approximately 2 µGy and the annual
effective dose equivalent would be about 2 µSv.
114. There are no published estimates of doses from
147Pm-activated clocks. In the case of 226Ra, the ratio of
the gonad doses from a watch and from a clock is 100;the same ratio will be assumed for 147Pm, although it isrecognized that the energies of the electromagnetic
radiation involved are much lower for 147Pm than for
226Ra. The gonad dose in a year to the user of a 147Pmpainted alarm clock would therefore be approximately
0.02 µGy and the effective dose equivalent would be
about 0.02 µSv.

(d)

Other radio/uminous devices

Collective doses from radio/uminous timepieces

115. The annual collective effective dose equivalents
arising from the use of radioluminous timepieces havebeen estimated, for the populations of Switzerland, theUnited Kingdom, and the United States, on the basis of
the number of products presented in Table 23, of theactivity contents per type of product and of thequotients of dose to activity given in previous
paragraphs. It is assumed that the gonad dose and theeffective dose equivalent have the same value. The
annual collective effective dose equivalents obtained
are 5. 33, and 17 man Sv for Switzerland, the United

117. Electronic and electrical equipment may give rise
to radiation exposure if they contain radioactive
substances or if they emit x-radiation owing to thedeceleration of electrons. Television sets belong to thesecond category and will be discussed later.
118. Radioactive materials provide pre-ionization ing;ises for the purpose of passing an electric current, sothat the equipment reads faster and more reliably, or
displays more constant characteristics [D4]. Examples
of application are starters for tubular fluorescent lamps,
trigger tubes in electrical appliances and excess-voltage
protection devices. The radionuclides mainly used are
85Kr, 147Pm and 232Tb. Although the number of articles
produced is very large, and the activities involved
significant (see Table 22), the doses resulting from thenormal use of such equipment can be expected to bevery small. It is only in the event of breakage throughaccident or disposal that the radiation exposure could
be significant.

3.

Antistatic de,·ices

119. Static
eliminators
contammg
radioactive
substances are widely used in industry to reduce theelectrical charge build-up on certain materials. The
radiation ionizes the air around a charged object andthereby allows the charge to be neutralized.
120. Static eliminators using alpha particles emitted
from 210Po are also manufactured and sold to thegeneral public in the United States. These devices areused to remove dust from phonograph records, photographic negatives and slides. lenses, etc. Each static
eliminator nominally contains about 20 MBq of 21opo
at the time of manufacture [N6}.
121. During the fabrication, polonium is interspersedin microspheres of ceramic material. which are thenfixed to an aluminium backing plate with epoxy
adhesive [N6]. The physical size of the microsphere islarge enough so that the inhalation of the material isunlikely in case of loose contamination. If ingested, themicrospheres are claimed to be insoluble in body fluids.
The only significant hazard to the user seems to result
121

from external irradiation due to the very small gamma
component of the 210Po decay scheme. The corresponding annual whole-body dose was estimated to beabout J0-8 Gy [N3]; the annual effective dose equivalent would be about 10-8 Sv.

30% by weight of uranium or thorium may deliver
substantial doses to the lens of the eye [W7]. The air
absorbed dose rate at the surface of a lens whichcontained 18% thorium by weight was measured bythermoluminescent dosimetry to be 10-s Gy h-1 [Ml 1].

122. In the United Kingdom, 210Po static eliminators
were subjected by the National Radiological Protection
Board to routine leakage tests and to special tests
intended to simulate severe but credible abuse andaccident with these devices [W5]. Under severe conditions (impact and fire), the containment integrity ofceramic rnicrospheres was found unsatisfactory and it
was considered possible that ICRP dose limits could beapproached or even exceeded.

128. High concentrations of uranium and thorium areoccasionally found in ophthalmic glass as a naturalconsequence of the glass manufacturing process [G 12].
In the United States, the Optical Manufacturers
Association issued a voluntary performance standard[07] to establish a uniform maximum limit forradioactive emissions for ophthalmic glass. The
standard states that the concentrations of 228Ac. 21:'Pb
and 214Pb in manufactured ophthalmic glass should notexceed 30 dpm g-1 (0.5 Bq g-'). This limit could produce
a maximum annual dose equivalent of about 5 mSv tothe corneal germinal layer [G 12].

4.

Smoke detectors

123.

Ionization chamber smoke detectors (ICSDs) use
alpha radiation to cause ionization in the air between
two electrodes, thereby allowing an electric current to
now across the air gap under the influence of a small
potential. Combustion products entering the air gap
become attached to the moving ions comprising theelectric current. Current flow is thereby reduced, andthe potential between the electrodes rises. Thesechanges trigger an electronic circuit, and an alarm isreleased [N3. 16]. ICSDs provide an early warning of afire condition.
124. Although some of the ICSDs now on the market
contain 226Ra, 238Pu, 85Kr, and 63Ni, the preferredradionuclide is 241Am. The use of ICSDs is widespreadin industrial, commercial and public buildings, andalso, at least in Canada and in the United States, inprivate homes. During the normal use of ICSDs, thedoses to members of the public are virtually limited tothose resulting from external irradiation.
125. Since 1972-1973 the residential market for 241Am
ICSDs has increased rapidly in the United States.
Fourteen million units containing 1.5 TBq of 241Am
were distributed in 1978 and 26 million units have been
distributed since 1972 [B5]. Belanger et al. [85) haveanalysed the radiation impact resulting frommanufacture, distribution. normal use and disposal of
those 1.4 107 ICSDs. Assuming that their useful life is
10 years and that disposal is by either sanitary landfill
or incineration, they calculated the collective
whole-body dose to be 11 man Gy, most of it resulting
from external irradiation during the useful life of the
ICSD. The corresponding effective dose equivalentwould be about 10 man Sv.

5.

Ceramic, glassware, alloys, etc., containing uraniumor thorium

126. The main uses of uranium in consumer products
are either as a pigment [S9] or in applications making
use of its high density. Thorium is used in incandescentmantles and in certain optical lenses.
127. The principal hazard from the uses of uranium
and thorium under normal conditions is the external
irradiation from the beta-emitting decay products. In
general, doses received will be small due to substantial
attenuation over the distance between the device andthe exposed person. In particular cases, this may not
apply, however. Some optical lenses containing up to122

129. Another example which has attracted interest is
the practice of incorporating uranium in the porcelainsused in restorative and prosthetic dentistry. In the
United Kingdom. it is estimated that about one in nine
adults has artificial porcelain teeth [06]; in the UnitedStates, that proportion is likely to be even higher [SlOJ.
A combination of uranium and cerium compounds isincorporated in the majority of modern porcelains inorder to simulate the fluorescence of natural teeth inday light and in artifical light. As all the isotopes ofuranium are radioactive, the tissues of the mouth areexposed to ionizing radiation from fluorescent porcelains.
130. An analysis performed by O'Riordan and Hunt[06] on 20 porcelain powders under five brand names
showed that 17 of the powders contained uranium, on
the average 0.041% by weight, with 2 having about 0.1%.
It is estimated in that study that for people with fluorescent porcelain teeth, the absorbed dose from external
irradiation in the basal layer of the oral epithelium
would be the limiting factor. Assuming a mass concentration of depleted uranium in the porcelain of 0.1 %.
the absorbed dose in that basal layer, taken to be at a
distance of 30 µm from the interface, was found to beof the order of 0.03 Gy in a year. As the ranges of thealpha particles emitted by the isotopes of uranium areless than 30 µm in soft tissues, most of the absorbed
dose is due to beta radiation. On the basis of that
estimate, the National Radiological Protection Board
has recommended that the use of radioactive nuorescers in dental porcelain be discontinued in the United
Kingdom [06]. Following that decision. the false-teeth
industry in the United States voluntarily agreed tostandardize the uranium content of procelain at
0.025-0.03% by weight [W7].
131. In the Federal Republic of Germany and theUnited States, the two countries where most of thedental porcelain seems to be manufactured, the massconcentration of uranium is limited by law. The
uranium content of porcelain powders and artificial
teeth should not exceed 0.1 % by weight in the Federal
Republic of Germany and 0.05% in the United States.
In the Federal Republic of Germany, an average
concentration of uranium in porcelain of about 0.03%
by weight was measured, none of the samples showing
an uranium concentration in excess of 0.1% by weight[S15, S16]. In a recent survey conducted in Japan, theaverage uranium concentrations in four brands (one ofwhich was from the United States) were found to be
0.0004%, 0.0009%, 0.002%, and 0.008%, the highest
measured value being 0.02% [Sl 7, S18].

B.

OTHER MISCELLANEOUS SOURCES OFRADIATION

132. The general public may also be exposed toconsumer products that do not contain radioactive
materials but that emit x-radiation owing to thedeceleration of electrons. The most familiar example ofsuch consumer products is the television receiver. The
exposures arising from the domestic use of television
receivers, the inspection of hand luggage by x-ray
equipment, and the use of x-ray tubes in secondary
schools will be briefly discussed. Reference [N3]provides a more.detailed treatment of the x-ray emitting
consumer products.
133. As indicated in the 1972 UNSCEAR report [U6],several surveys conducted in the 1960s showed that asmall proportion of the colour television sets emitted xradiation in excess of the limit recommended by the
ICRP, that is 0.5 mR h-1 (corresponding to 1.29 10-1 C
kg-I h-1) at 5 cm from the surface of the television
receiver. Modern television receivers have low x-ray
emissions, as shown by several sets of data. Thisconclusion is supported by the results of measurements
recently conducted in the Federal Republic of Germany[K 10] and in Asia [W8]. In the first of these surveys,
conducted in 1972, it was found that the average
exposure rate 5 cm from the surface of the colour
television receivers was about 3 10-S C kg-I h-1 and thatthe estimated annual gonad dose, under normal
viewing conditions, was of the order of 10 µGy.
Assuming that the effective dose equivalent (expressedin µSv) is approximately equal to the gonad dose
(expressed in µGy), the corresponding annual effective
dose equivalent would be about 10 µSv. In the second
survey the exposure rate at the surface of 28 randomly
chosen colour television receivers was found to varyfrom about 3 10-10 to 2 10-S C kg--1 h-1 under normal
working conditions.
134. X-ray fluoroscopic scanning systems are used atmost airports to inspect hand-carried baggage. The
traveller often walks alongside the cabinet-type x-ray
equipment as his or her luggage is being examined. The
average exposure to the traveller per air trip due to theinspection of hand luggage was estimated in 1973 to beless than 4 10-10 C kg--1 in the United States [N3]. The
corresponding effective dose equivalent is about 7 nSv.
135. Surveys conducted in Canada and in the UnitedStates in the early 1970s revealed that significantly large
numbers of demonstration devices capable of emitting
x rays were being used in secondary schools of thosecountries [Zl]. In Canada, exposure rates ofup to 910-3
C kg--1 h-1 were measured at a distance of 0.3 m fromthe surface of cold cathode x-ray tubes [Zl]. Assumingthat the energy of the x rays involved is 50 keV, thecorresponding effective dose equivalent rate would be
about 0.1 Sv h-t. Most of the school teachers demonstrating the x-ray tubes had little or no knowledge ofradiation protection principles or practices.

VII.

SUMMARY

136. This Annex deals with some examples of technologically modified exposures to natural radiation whichhave been brought to the attention of the Committee. Itis very likely that those examples do not present thecomplete picture of technologically modified exposures
to natural radiation; indeed, the lack of rigour in thedefinition of such exposures (see paragraph 3) makes acomprehensive picture impossible. From the assessments presented at the current level of industrial andnuclear and coal cycle wastes utilization. the exposures
do not add significantly to the collective effective dose
equivalent on the global scale but may give rise. inlocalized areas or for people exposed under extreme
conditions, to appreciable increases in individual
exposures from natural radiation. The present state ofknowledge does not allow an accurate estimate of thecollective effective dose equivalent from technologically modified exposures to natural radiation to be
made, and further measurements are required in thisfield.
137. Some examples of miscellaneous sources ofradiation exposure have also been considered in thisAnnex. Many millions of units of various types ofconsumer products containing deliberately incorporated radionuclides are in everyday use around theworld. Estimates of doses in individuals resulting fromthe use of such products show that in all cases thesedoses are small. The highest calculated effective dose
equivalents result from the wearing of radioluminous
watches, which are the most widespread radioactive
consumer product. The assessment of the global
collective effective dose equivalent from these sources
is hampered by wide gaps in the knowledge ofimportant factors such as the activities involved, thenumber of products on the market, and the problems
related to the disposal of those devices. Even for themost common product, watches, the data are notalways available since watches are generally not subject
to control. Nevertheless. owing to international recommendations, and national regulations in somecountries, there is a gradual improvement of control. It
is likely that the average annual effective dose equivalent due to the use of consumer products is less than
10 µSv. almost entirely due to radioluminous
timepieces. However, in view of the growing number
and diversity of consumer products, it is important toensure that proper control is maintained over their use
and disposal.

123Ta b 1e
Activitt concentration of radionuclides in coal sameles(Bq kg-!)238 u decay series

Origin40K
Australia
13razi l
CanadaCzechoslovakia
China
Gennany, Fed. Rep. of
Bituminous coal
Brown coa 1
Hungary
India

23Bu

226Ra

232 Th decay series
21Dp 021orb

30- 48100
30
4.1- 13
7

370
440

< 40
15

20
< 10

1.5
25

232Th

15-25
250

4-15

25
10

30
10

< 20
<7

35
25-50

70-110

20
27

fM12)

[Ml]

30
7-110
20

30

[T2]
[T2]
[Sl]

22

16
8.9
0.52
14
< 20

[L4]
17
2.4-19

7.4-94

18
16
18

[JBJ
[JS]
[ J 1J

[Ml]

28

17
11-29

l

[JI)
[ J 1J

38

2-140

[81]
[Sl
[Sl

67
26

Italy

Lignite from central Italy
Lignite from Sardinia
PolandAverage290
Range
37-760South Afri ea
110
USSR
Average
120
United Kingdom
Average
120
Range
United States
West
110
Illinois and Kentucky
44
Alabama, Tennessee, Kentucky 120
Wyoming 1
Wyoming 2
Applachia, Illinois, Montana,Pennsylvania, and Wyoming
70
Country average ~./52
Venezuela
110

Ref.

228Ra

17
10
31

13
8.5
27
41
8.9
21
< 20

[HJ]
[C4]
13

[Cl]
[K2J
[BJ]
[Kl]
[S2]
[82 J

(82)
[Sl]

a/ Arithmetic mean activity concentrations of 910 samples of coal originating from several United States mines.
The results, given in reference [B2), are compiled from data contained in references fF2], [G2], and [S3_).

124

Ta b 1e

2

Activiti concentrations of natural radionuclides in ash sameles(llq kg-l)

Type of ash
and origin

23 8u decay series
40K

232Th decay series

23Bu 226Ra 210Pb 2101'0 232 111

IJOTTOM ASH (slag)
Australia
250
Germany,
Fed.Rep.of!3C(I)
17C al
520
(2)
Japan
Centra 1
740
4Southern
37
300
Northern
2C 3900
PolandAverage
48
500
Range
280-1200 17-100
USSR
7e
370
United States
West
81
30
BI
240
Ill. and Kent.
480
180
Pennsylvania
480
67
59
Wyoming 1
2C
37
Wyoming 2
93
210

Ref.

228Ra

fBI]

96
140
560
90
250

7.4

[J3]

[S!J
44
20
55

44
15-120
70
67
59
52

[fHJ
[Nl]
IN!]

fT2)
(T2)
fl4]
67

190

FLY-ASH (collected)
Germany, Fed.Rep.ofBituminous coal
200 2000 2000
300
100
Brown coal
70
4C
60
100
30
India
100
Italy
Centra 1
80-100 40-70 44-330
300
Sardinia
1000
PolandAverage
97
74
730
Range
33-130180-1500 44-170
United States
14(:
Appalachia 1
96
7Q
Appalachia 2780
52Appalachia 3
lOQ
410
44
Appalachia 4
700
96
9C·
89
I 11. and Kent.
81
590
130
Pennsylvania
85
85
78
700
Wyoming 1
3C
370
480
Wyoming 2
210
200
160
West
10(
78
81
260
110
Appalachia,
170
480
89
Midwest and WestFLY-ASH (escaping)
Austra 1i a
520
Germany, Fed. Rep. of
Bituminous coal
300
300
Brown coal
70
100
Hungary
20-560
United States
West bi
260-270
Wyoming-I
1~
Wyoming 2 cl
200

228Th

130

[Cl]
fK2J
[B2J
[S2l
[S2]

(J7]
(J7]
fM12]
[Ml]
[Ml)
(T2]
[T2]

89
44

81

[El]

[B3]
fGJJ
fB2]
[K2l
[B2
(Kl]
1
IS2
J
rc1 J
fFl)

[Bl]
3000
200

5500
300

160-630
630
700
410
250

100
40

rJ7J

TJ7]
fP2]

100-120 100-160 rc1J
[Kl]
fS2]

al Derived from the assumption that radium-228 is in radioactive equilibriumwith thorium-228.
y Range of values obtained for four cifferent size fractions (2.4 to 18.5 um
mass median diameter).
cl Derived from the assumption that the enrichment between collected and escaping
fly-ash is equal to 1.3 for uranium-238.

125

T a b l e

3

Measured enrichment factors in escaping fly-ash~82]
Enrichment factor in escaping fly-ash
Uranium
1.3

226Ra

210Pb

1-2
1. 7 b/

1-5
11 c/
1
5

1
2

210Po

Thorium

228Ra

Percentage
of fly-ash
released

1.0-1. 2 1.0-1.6
1.4
I. 7 b/

Ref.

< 3
0.47
3.5
4.8
7.5

5

[Cl J a/[K2] [K2][Kl](Bl][N2] <J_/

6-10 c/Range for various size fractions; the variation with size is presented
in Figure I.
Estimate of Beck et al. [82] from measurement of barium.
Measurements for stable lead.
Range of composite samples of different size' fractions from 8 power plants;
maximum enrichment for particles of l-2 µm diameter.

a/
b/

cl

a/

Ta b l e

4

Estimates of average activity concentrations of natural radionuclides
in escaping fly-asn ana OT annual atmospneric oiscnarges
per unit energy 2eneratea
238u decay series

Origin40K

238u 226Ra

210Pb

232Th decay series
21Dp 0 232Th

228Ra

Ref.

228Th

ACTIVITY CONCENTRATIONS IN ESCAPING ASH (8q kg-l)
UliSCEAR,
1977 report
Averages of Table 2
Adopted values

600
265
500

200
200
200

40
240
200

400
930
600

400
1700
600

40
70
200

40
130
200

40
110
200

ru2]

ESTIMATED ATMOSPHERIC DISCHARGES
per unit energy generated (t1Bq per GU a)
France1981 3500
Germany, Fed.Rep. ,1981
Brown coal
Bituminous coal
Bituminous dry ash
removalBituminous liquid
ash removal
India
1980
Italy ( 1) a/ 1979
(2)
USSR
1978 20000
United Kingdom 1980 1000
United States, 1964
1970
1977
1977
b/ 1977 6702000
c/ 1977 1100
~I 1977 10000
UNSCEAR,1977 report
5500
This report
4000
a/
b/

cl

9./

126

'A4;

7000

7000

6000

100
500

70
500

200
4000

400
8000

40
200

40
200

40 'J7,S19;
200 'J7]

300

200

200

300

100

200

100

rH4]

200
200
300 2000 6000
11000
15000
18000
4400 4400 15000
26000
18000 18000 26000
2000 8100 7400 2000 1100
1000 1000 1000 1000 1000 1000
640
400
300
300
270 270
300
300
200
200
300 300
6300 6300
4900 5600
110- 110150- 140- 670- 670370
370
410 410 2000 2000
410
410
1000 780 2600 2600
4700 4700 9300 9300 3800 3800

200

fH4j
fM12]

500

1850 370
1500 1500

3700
5000

3700
5000

370
1500

370
1500

run

1000

[Ml]
'll'.
'.C4 J

200
6300
110370
410
3800

'82]
;82]

370
1500

The two plants considered burn lignite of low heat content, high ash
fractions, and high activity content, resulting in elevated discharges.
Range of releases reported for plants burning different types of coal.
Modern plant.
1972 reference plant.

: El]
rr12]
'M3]
fN3J
!L2]

'U2]

Ta b 1 e

5Conmitted doses per unit activitf inhaled (µGt Bg- 1)of the most im ortant natural raaionuclides re-eased from coal-fired ewer

Uranium decay series

Organ or tissue

lants

Thorium decay series

230Th

226Ra

222Rn a/and daughtersz'lDPb210p 0Lungs
5,5Bone surfaces
0.06
Red bone marrow
0.004
Liver
0.0001Kidneys
0.025
Spleen0.0001
G.!. tract
0.0007
Other soft tissues 0.0001

6,6
6.0
0.07 460.004 3.6
0.0001 0.075
0.029 0.01
0.0001 0.01
0.0008 0.01
0.0001 0.01

0.4
0.17
0.015
0.002
0.002
0.002
0.003
0.002

0.0093 (T-B)
0.0012 (P)

0.2
0.8
0.085
0. 35
0.17
0.03
0.006
0.01

0.5
26
0.01 2400.01 20
0.01
0.065
0.25
0.007
0.45
0.007
0.006 0.008
0.01
0.007

15
0.2
0.15 200.015 1.7
0.004 0.15
0.004 0.02
0.004 0.02
0.004 0.025
0.004 0.02

0.011
0.013
0.001
0.002
0.008
0.0003

Effective dose
equivalent perunit activity
inhaled (µSv Bq- 1 ) 13

15

1.1

0.013

2.0

2.2

0.61

0.051

23Bu

234u

51

232Th

250

228Ra

228Th

51

220Rn
and daughters

0.0001a/ The committed doses and effective dose equivalents per unit activity inhaled of the short-lived decay productsof the radon isotopes are estimated from data in Annex D. For the radon-222 daughters the effective dose
equivalent is obtained from the absorbed doses in the bronchial basal cell layer (T-B) and the pulmonary
epithelium (P). Only the doses due to the a particles are taken into account,T a b 1 e

6

Estimates of collective dose commitments er unit ener
eneratedresu ting from atmosp eric re eases rom coa -fire power pants(10- 3 man Gy per GW a)
Inhalation during the passage of tlie cloud.

Thorium decay series

Uranium decay series
Organ or tissue

Lungs
Bone surfaces
Red bone marrow
Liver
Kidneys
SpleenG. I. tract
Other soft tissues

Total(rounded)

230Th

226Ra

222 Rn anddaughters !I

210Pb

210p 0

232Th

228Ra

229rh

19
23
21
0.2
160
0.2
0.01
0.01
12
0.0003 0.0003 0.3
0.09
0.1
0.03
0.0003 0.0003 0.03
0.002 0.003 0.03
0.0003 0.0003 0.03

1.4
0.6
0.05
0.007
0.007
0.007
0.01
0.007

0.69 (T-B)
0.09 (P)

2.3
9.2
0.1
4.0
2.0
0.3
0.07
0.1

5.8
90
0.1 830
69
0.1
0.1
0.2
2.9
0.02
5.2
0.02
0.07
0.03
0.1
0.02

0.7
0.5
0.05
0.01
0.01
0.01
0.01
0.01

52
69
5.9
0.5
0.07
0.07
0.09
0.07

210
1070
89
5
5
6
0.3

0.4

0.1

2.3

2.5

0.2

18

140

238u

Collective effective
dose equivalentcommitment per unit
energy generated
4.5(10- 2 man Sv (GW a)- 1 )

234u

5.2

18

86

0.4

a/ T-B and P stand for bronchial basal cell layer and pulmonary epithelium, respectively,127

T a b 1 e(10

7

man Gy per GW a)r:ct.r,1•11al and irzte1?1al ir1'adfot.i= d11e to the ,wtiin'.Lu JepoM'.ted,

Uranium decay series

Internal irradiation
Lungs
Bone surfaces
Red bone marrow
Liver
Kidneys
Other soft tissues

230u

234u

230Th

226Ra

0.2
2.6
0.4
0.2
1.6
0.2

0.1
2.4
0.3
0.1
1.4
0.1

0.6
8.9
0.7
0.008
0.3
0.008

0.2
6.8
0.7
0.2
0.2
0.2

0.6

0.9

0.9

Collective effective
dose equivalentconmitment per unit
energy generated
0.6(10- 2 man Sv/(GU af 1)External irradiation
All tissues(10- 3 man Gy (GW a)- 1)
2_/

Thorium decay series

222Rn
and
daughters
E._/

2l"liJ,i;and
210p 0232n,

140 (T-B)
19 (P)

5.2
69
12
9.7
9.7
9.7

0.5
2.4
0.2
0.5
0.7
0.004

3.0
5.5
0.5
1.0
1.9
0.1

20
24

22

0.3

1.6

9.4

20

220Rn
228Ra
Total
and
and
(rounded)daughters daughters
!I

54

35

T-B and P stand for bronchial basal cell layer and pulmonary epithelium, respectively.

Ta b 1e8

Estimates of collective effective dose e~uivalent commitments
eer unit energy genera ea
resultin from atmos her1c releases from coal-fired ower lants( 10 man Sv per GW a)Radionuclide

Inhalation
duringthe cloudpassage

238u
234u
230Th
226Ra
222 Rn+daughters

18
0.4
0.1

210Pb+210p 0

5

232Th
228Ra+daughters
220 Rn+daughters

86

4
5

18

Total (rounded) 140

128

Interna 1
irradiation
due to theactivity
deposited
0.6
0.6
0.9
0.9
20
22
0.3
2
9

56

Externa 1
irradiation
due to theactivity
deposited

Total

4

82

l l
5

120

9

200

1.9

3.6
14
0.2

170 (T-B)
49 (P)
120
17
15
30
11

56

90

Table9

Production of phosphate rock in 1977
and reported activity concentrations of natural radionuclides
Production of marketable Activity conc~?trations
rock in 1977
(Bq kg )(10

I.JORLD
China
a/Christmas-Islands
IsraelJordanMorocco (1)

9

kg)

125.7
4.1
1.3
1.2
1.8
17.6

Percentageof the world
production

1.1
1.8
2.9
3.6
24.2

3.3
1.0
1.0
1.4
14.0
0.9
1. 4
2.3
2.9
19. 3

232 Th

150
150
330
300
1500-1700
1300-1850
1700 1700
1500 1500
1700 1570
810
850
1300 1400
1300 1200
590
520

25

90
70
44

(2)

(3)

Kola, phosphorite
47.3
United States
Central Florida (1)Central Florida (2) (pebble)
North Florida, pebble
Florida, land pebble
and soft phosphate
FloridaArkansas
Idaho
Montana
North Carolina
OklahomaSouth Carolina
Tennessee, brown rock,blue rock, white rock,phosphatic limestone
Utah
Wyoming
Viet Nam
1.5

226 Ra

40K

100

(2)
(3)

Nauru
Senegal b/
Togo
Tunisia
USSR
Kola, apatite (1)

Ref.
238u

~7.6

::1sJ
{HS]

7

30
30
20

rJ3]
'03)
r11s J

200

fC2)

10

'P6)
'115)
'f15,

7

67
110

92

1: 100

40
70
30
390

91
92
78

170

25

230

1500
1700
800

1600
2100

16

1900
1300
370
1850
1400
960
300
4800

2000

150
1600
2300

150
1850
2300

1.2

44

410

1800
1500
670
370
4800

59
30
52
30
25
40
30
78

'C2)
'115;
'.P6]
fG6]

'114]
fR4)
rR4]

1000

1270

tc2j
'MS)

'MS]
48

f P6]

rr1s;
rMs;
fMS]

'MS)
filS]
~115]

20

'MS)

30
10

'.MS)
'.f15]'115]

a/ Samples from China, India, and South-East Asia.
b/ Samples from Senegal and other African countries.

129

Table10

Data on discharges from phosphate industry operations
Annua 1
input ofmarketableore
9(10 kg)Type of plant

23 8u

230 rh226 Ra232 Th Ref.

a/

Ore drying plantliet process phosphoric acid plant
Plant A
Plant B b/
Uranium recovery plant

2.7

Airborne annual discharges(MBq)
245
250
250
rP4]

1.2
1.2
0.4

9.2
8.7
6.8
1300 1200
540
350 sma 11 small sma 11

'P4;
rp4J
'D2)

Activity concentrations, in liquid di scha r9es
(Bq m-3 }Phosphate mine and beneficiation plant
Heavy slime: undissolved
dissolved
Effluent:
undissolved
dissolved
Wet process phosphoric acid plant
Plant I: Field survey number I
Untreated process water
Outfall (after chemical treatment)
Field survey number 2
Untreated process water
Outfall (after chemical treatment)
Plant 2:
Untreated process water
Outfall (after chemical treatment)
Plant 3:
Untreated process water
Outfall (after chemical treatment)a/li/

2500(400-80000) fG4'.
J
65(20-80}(G4]
20( 5-40}'G4)
rG4]30 (1-80)
39000
20

2600
20

3000
170

170
1.5

15000
620

3700
30

2000
70

120 'G4]
4 [G4]

68000
12

15000
5

3200
17

230

rG4J

24000
10

320
HD

2000
94

150

[G4J
[G4J

'.G4)
'.G4]

rm [G4J

tm

Reported or estimated.
The airborne discharges from plant Bare very uncertain and likely
to be overestimates.

T a b l e

11

Estimated distribution of the activit
resent,n t e p osp ate ert, 1zers
produced ,n the United States during 1974

[G4]

Mass

Activity (TBq}

Material

Marketable ore used for
fertilizer production
Normal superphosphate
Concentrated superphosphate
Ammonium phosphates 2-I
Phosphoric acid
Other fertilizer production
Gypsum

25.6
3.1
3.4
5.3
10.0
2.0
25.2

8.0
0.6
1.6
2.4
3.1
0.3

40
2.4
2.6
0.37

39
2.3
7.0
13
9.4

40
2.1
5.9
13

0.4
0.07
0.04
0.07

10

I. I

31

5.7

12

0.3

I. I

a/ Does not include phosphoric acid used to produce diammonium phosphates
and concentrated superphosphates.

130

Ta b l e

12oses ar, sRadionuclide

Airborne
discharge(Bq t- 1)

Collective dose corrrnitments per unit mass of phosphate ore (10- 9 man Gy t- 1)
Lungs
a/

Bone
surfaces

Red bonemarrow

Liver

Kidneys

238u
234u
230Th
226Ra
222Rn

90
1.1
90
1.4
90
1.2
90
0.08
1.5 106 [ 172.2(T-B)
(P)

0.01
0. 01
9.5
0.04

0.00090.00090.7
0.003

Ore drying plant
0.000020.005
0.00002
0.006
0.02
0.002
0.00040.0004Total[ 17 (T-B)
6 .0 (P)

9.6

0.7

0.02

0.01

Spleen

G. I.
tract

Other soft
tissues

0.000020.00002
0.002
0.00040.00010.00020.002
0.00060.000020.00002
0.002
0.0004

0.002

0.003

0.002

Wet process phosphoric acid plant (Plant A)
23Bu
234u
230Th
226Ra
222Rn

0.09
0.1
7
0.1
6
0.006
1.5 106 [ 172 .2(T-B)
(P)

Total

[ 17 (T-B)
2 .S (P)

7
7

0.001
0.001
0.7
0.002

0.00006
0.00006
0.06
0.00020.000002
0.000002
0.001
0.000030.00040.00050.00020.000030.000002
0.000002
0.00020.000030.00001
0.00001
0.00020.00004

0.000002
0.000002
0.00020.00003

0.7

0.06

0.001

0.001

0.00020.00030.0002

Wet process phosphoric acid plant (Plant B)
238u
234u
230Th
226Ra
222Rn

1000
13
1000
15
13
960
440
0.4
1.5 106 [ 172.2(T-B)
{P)

Total

[ 17 (T-B)
44 (P)

0.1
0.2
100
0.2

0.009
0.009
8.0
0.02

0.00020.0002
0.2
0.002

0.06
0.07
0.02
0.02

0.00020.0002
0.02
0.002

0.002
0.002
0.02
0.003

0.00020.0002
0.02
0.002

100

8.0

0.2

0.2

0.02

0.03

0.02

Uranium recovery plant
238u
234u
Total

850
850

13

0.1
0.1

0.008
0.008

0.00020.00020.05
0.06

0.00020.0002

0.001
0.002

0.00020.0002

24

0.2

0.02

0.00040.1

0.00040.003

0.000411

al T-B and P stand for bronchial basal cell layer and pulmonary epithelium, respectively.

131Ta b1 e

13
hos hate ore
ans:

oses

Radionuclide

Collective dose corrmitments per unit mass of phosphate ore ( Io- 9 man Gy t - l )Airborne
discharge(Bq t- 1 )External
irradiation
All tissues

Internal irradi~tion
Lungs
a/

Bone
surfaces

Red bonemarrow

Liver

Kidneys

Other soft
tissuesOre drying plant
238u
234u
230Th
226Ra
222Rn

90
90
90
90

I

2.1

Total

0.009
0.009
0.03
0.01
8.6 (T-8)
1.2 (P)

0.2
0.1
0.5
0.4

0.03
0.02
0.04
'0.04

0.009
0.009
0.0005
0.01

0.09
0.09
0.02
0.01

0.009
0.009
0.00050.01

8.6 (T-B)
1.3 (P)

1.2

0.1

0.03

0.2

0.03

Wet process phosphoric acid plant (Plant A)
238u
234u
230Th
226Ra
222Rn

7
7
7
6

I

0.1

Total

0.01
0.00070.01
0.0007
0.04
0.003
0.03
0.0008[ 0.6 (T-B)
0.08 (P)

0.002
0.001
0.003
0.003

0.00070.00070.00004
0.0008

0.008
0.007
0.001
0.00090.00070.00070.00004
0.0009[ 0.6 (T-B)
0.09 (P)

0.009

0.002

0.02

0.002

0.03

Wet process phosphoric acid plant (Plant B)
238u
234u
230Th
226Ra
222Rn

1000
1000
960
440

Total

10

0.1
0.1
0.4
0.06
f 42 (T-B)· 5.6 (P)

1.8
1.6
5.7
2.0

0.3
0.2
0.4
0.2

0.1
0.1
0.005
0.06

1.0
1.0
0.2
0.06

0.1
0.1
0.005
0.06

[ 42 (T-B)
6.3 (P)

11

1.1

0.3

2.3

0.3

Uranium recovery plant
238u
234ll
Total

850
850

0.09
0.08

1.5
1.4

0.2
0.2

0.09
0.08

0.9
0.8

0.09
0.08

0.2

2.9

0.4

0.2

1. 7

0.2

al T-B and P stand for bronchial basal cell layer and pulmonary epithelium, respectively.

132

Ta b l e

14

Acti vit concentrations of natJrall occurrin
in e ose ate ert1 uers
(Bq ~g-1)
Type of fertilizer
TREATEO ROCK PliOSPHATES
ApatitePhosphorite
Conce.ntrate obtained byflotation
Calcined, ground soft,
partly converted rockphosphate, etc. a/radi onuc 1ides

Country 238u 230Th 226Ra 210Pb 210p 0 232Th 40K Ref.
USSR
USSR

30
390

25
380

30
480

60
25

100 !G6]
230 rG6]

USSR

420

390

290

20

73

25

110 'PG J

FRG b/

670

480

[G6)

OHE-COMPOilENT PIIOSPHATE
FERT Ill ZERS
Superphosphate
Superphosphate
Superphosphate
Superphospha te
Triple superphosphate
Triple superphosphate

FRG b/ 529
USSRUSA c/ 740 670
Belgium 1100
FRG b/ 800
USA 2100 1800

PK-FERTILIZERS d/

FRG !:_/

410

370

15 5900 'P6)

llP-FERT Ill ZERS
NP-fertilizers a/
Ammonium phosphate
fli trophosphate
Nitroarrrnonium phosphate
tlonoammon i um phosphate
Diammonium phosphate

FRG b/ 920
USSRUSSR
USSR
USA
2000 1800
USA
2300 2400

310
100
850

48

NPK-FERTILIZERS e/
IIPK
IIPK
NPK

FRG b/
USSR
Belgium

440

270

470

210

15 5200 rp6,•
J1200 !G6)
1<15 5900 rc2•
JBASIC SLAG

Belgium

23

19

'K4]

~/

b/

s./
d/
e/

520
110' 300
790
910
230
780

140 f P6]
120 'G6]
201114 J<25 <180 ic2;
44
52 'PG)48'i~4 J
15

150

44

30
870
15

920
15

20
210

9

15

20

rp5J
'G6J
fG6)
!GG;

41

10
30
63
15

"M4 ~

'114 J

54

Assuming a P2o5-to-fertilizer mass concentration ratio of 0.28.
Federal Republic of Germany.
United States.
Assuming a P o5-to-fertilizer mass concentration ratio of 0.16.
2
Assuming a P2o5-to-fertilizer mass concentration ratio of 0.13.

Tab l e15

Estimated collective dose colllTiitBent er unit mass of marketable rockar1s1ng rem t e use o e ose ate ert1 1zers(10- 7 man Gy t- 1)

Internal irradiation
Lungs
Bone surfaces
Red bone marrow
Liver
Kidneys
Other tissues
External irradiation
All tissues

238u

234u

230Th

226Ra

0.3
5.3
0.9
0.3
3.1
0.3

0.3
4.8
0.6
0.3
2.9
0.3

1.1
18
1.3
0.02
0.6
0.02

0.3
9.0
0.9
0.3
0.3
0.3
1.5

222Rn

210Pb

Total

[ 190 (T-B) 5 0 [190 (T-B)•
26 (P)
33 (P)
66
100
11
15
9.3
10
9.3
16
9.3
10
1.5

133

Ta b 1 e

16

Estimates of collective effective dose e uivalent commitments
per unit mass o mar eta e ore
due to the exploitat1on of phosphate rock(10- 6 man Sv t- 1)

Source of exposure

Atmospheric discharges
from an ore drying plant
Atmospheric discharges from wetprocess phosphoric acid plant A
Atmospheric discharges from wetprocess phosphoric acid plant B
Atmospheric discharges froman uranium recovery plant
Agricultural use ofphosphate fertilizers

Activity deposited

Cloud
passage
Inhalation

Internal
irradiation

External
irradiation

Total

0.04

0.01

0.002

0.05

0.03

0.00090.0001

0.03

0.2

0.06

0.01

0.3

0.05

0.007

0.06

50

15

65

Interna 1
Externa 1
irradiation irradiation
Use of by-product gypsum asbuilding material in homes

17000

Ta b 1 e

16000

Total
33000

17

Activity concentration of naturally occurring radionuclides
1n 6ui101ng materials
expected to give rise to higher-than-average external absorbed doses

Type ofbuilding material

No. ofCountry samples~I

Natural origin
Gran, teGranite bricks
GraniteLi thoid tuff
Pumice stone
Concrete containing
alum shale

34
FRG
UK
7
USSR
2
Italy
FRG
20
Sweden 83

Industrial ori~in
Phosphogypsumrom FRG
39
phosphorite
PhosphogypsumUK
6
Phosphogypsum
USA
Calcium silicate slag Canada Calcium silicate slag USA
Red-mud bricks
FRG
23
Fly-ashFRG
28
Fly-ash type 1
UK
1
type 2UK
1
type 3
1
UK
Blast-furnace slag USSR
29
Slag aggregate c/ Finland 3

~I

,1b/
134

Average activity concentration Absorbed
dose rate(Bq kg-!)in air a/ Ref.
40K
226Ra
232Th
(l0- 8Gy h-l)
1200
1000
1500
1500
1100
850

100
90
110
130
130
1500

80
85
170
120
130
70

30
28
45
40
35
145

(K6 J

110

600

<5

54

[SS]

70

800
1500
2150
1300-1500
280
210
7
140
50
70
100

20
7

330
700
550
550
220
240
190

230
130
40
30
44
20
70

'S5 1

iHil
I

'

'.NS J

;ssJ
(S6)

(HI)
68
126
[G6;
184
(PS)
110-130 IB4]
58
.SS]
1551
42
j
10
20
!Hl J
12
,HI]
11
(K6]
19
:us]

;HI

The absorbed dose rates in air have been calculated assuming a 4 n geometry
and an infinite thickness of material. The values obtained are an index
allowing the comparison between building materials and·not an estin~te ofthe doses that would be received in dwellings constructed with thosebuilding materials.
Federal Republic of Germany• FRG; United Kingdom~ UK; United States= USA.
Mixture of coal clinker, ash, and cement.

Tab l e

18

Variation of the galactic dose rateand dose equivalent rate with altitude[04]

Absorbed dose Dose equivalent
rate
rate
(µGy h- 1)(µSv h-l)

Altitude
(km)

0.14
0.33
0.84
1.75
3.01
4.62
5 .92
7.09
7.72

4

6
8
10
12
14
16
18
20

a/

a/

0.20
0.51
1.35
2.88
4.93
7.56
9.70
11.64
12.75

Values averaged over 2 geomagnetic latitudes (43° and 55°) and over two
periods of solar activity (mininum and maximum).

T a b l e

19

Comparison of calculated cosmic-ray doses
to a erson flying in subsonic and su ersonic aircraft
average soar con itions[W2]

Subsonic flight at 11 km Supersonic flight at 19 km
RouteFlightduration(h)

Dose perround trip
(10- 5 Gy)

Flightduration(h)

Dose perround trip
(10-S Gy)

11.1
8.3
7.4
7.0
5.2
17.4

4.8
3.6
3.1
2.9
1.9
4.4

3.8
2.8
2.6
2.4
1.9
6.2

3.7
2.6
2.4
2.2
1.3
2.1

Los Angeles - Paris
Chicago - Paris
New York - Paris
New York - London
Los Angeles - New York
Sydney - Acapulco

Ta bl eons ace missions

Absorbed dose

Mission or
missionseriesLaunch date

Apollo VII
Apollo VI I IApollo IX
Apollo X
Apollo XIApollo XII
Apollo XIVApollo XV
Vostok 1-6
Voskhad I, 2
Soyuz 3-9

Aug, 1968
Dec. 1968
Feb. 1969
May 1969
July 1969
Nov. 1969
Jan. 1971
July 1971

20

Duration of
missionType of orbit

Dose(10- 5 Gy)

Earth orbital
Ci rcuml unar
Earth orbital
Circumlunar
Lunar landing
Lunar landing
Lunar landing
Lunar landing
Earth orb ta 1
Earth orb ta l
Earth orb tal

120
185
210
470
200
- 200
- 500
- 200
2-80
30,70
62-234

(r)

260
]l7
2'1
192
182
236
209
286

135

Table21

Breakdown of the absorbed dose and dose equivalenton spacecraft mission Apollo XI[E2]Absorbed dose
( 10- 5 Gy)

Component

Dose equivalent(I0- 5 Sv)

150
15

Protons
Stars
Fast neutrons
Heavy nuclei
Electrons andgarrrna rays
TOTAL (rounded)

- l

5
- 30

220
94
- 12
46
- 30

200

400

22

Ta b l e

Consumer products in the Federal Republic of Germany[W3]

The data :refe1• to the yea:rs 1973 Ol' 1975,
dep~mdir.g on the pPOduct.

Produced in the Fed. Rep. of Germany
Type of consumer product

Number of Total activity
andpieces orradionuclide
weightused

Exported

14 106

40 TBq 3H
10 TBq 147 Pm

50 %

7 106
26 10615 GBq 232 Th
3 TBq 85Kr

20 %
50 %

Radioluminous timepieces
Devices containing scales
or dials with luminous
paintElectronic and electricaldevices
High-pressure mercury lamps
Ignition devices forfluorescent lamps
Electronic components
containing radioactive
substances
Electronic tubes
Antistatic devices

8 10 5 ( 3H)l 105 (147Pm)

3 104

210Po

?

Smoke detectorsl40 106 200 ,,, 85 ,,3
147 Pm 40 %11 106 10 TBq H or
232
6
0.2 GBqTh
3 10
7 105 [ 3H, 60Co , 63Ni
147Pm, 226Ra!lumber ofpiecesimported
into theFed.Rep.of
Germany

1 10

5

226Ra, 241 Ani

Ceramic, glassware, alloys,
etc. containing uraniumor thorium
Articles with uranium paints 3 105 0.6 GBq 238 u
Glassware containing uranium 4 10 3 kg 2 GBq 238 u
Glassware containing thorium 16 103 kg 7 GBq 232 Th

Ta b l e

50 %
50 %
10 %

l 10

3 10

6

5

23

Estimated number of radioluminous timepieces
1n use in the various countries

Watches (10 6 )Country

Switzerland
United Kingdom
United States

136

Ref.

Year

1976
1978
1977

2.6
5
27

0.64
0.21

0.07
0.8
negligible

147Pm

226Ra

I. 4

1.6

0. 38

[K9)

0.98

2.3

8.4

[TI)
(M8)

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