background radioactivity in environmental materials
TRANSCRIPT
J. Environ. Radioactivity 9 (1989) 265-280
Technical Report
Background Radioactivity in Environmental Materials
ABSTRACT
This paper presents the results of a literature search to identify information on concentrations of 'background' radioactivity in foodstuffs and other commonly available environmental materials. The review has concen- trated on naturally occurring radioactivity in foods and on UK data, although results from other countries have also been considered where appropriate. The data are compared with established definitions of a 'radioactive' substance and radionuclides which do not appear to be adequately covered in the literature are noted.
INTRODUCTION
This paper represents a summary of work prepared by Associated Nuclear Services (ANS) for the Central Electricity Generating Board (CEGB), under contract no. NW/AWP/F5292 , being a literature search to collate information on background radioactivity in foodstuffs and other common- ly available environmental materials. The review has concentrated on UK items, although relevant data from other countries have been considered. The search has been confined as far as possible to measurements not affected by the Chernobyl accident and to foodstuffs not in the vicinity of nuclear installations, to ensure that they reflect true background concen- trations from naturally occurring radionuclides and residual activity from weapons fallout.
It should be noted that this work makes no attempt to discuss the relative significance of radionuclide concentrations in terms of any poten- tial harm to humans. A given concentration of one radionuclide in a foodstuff does not have the same radiological significance as the same concentration of another radionuclide.
265 J. Environ. Radioactivity 0265-931X/89/$03.50 © 1989 Elsevier Science Publishers Ltd, England. Printed in Great Britain
266 I', R Maul, J, P. O'Hara
L IT E R AT UR E SEARCH
Information has been obtained on background radioactivity in a variety of foodstuffs and other common environmental materials. The radioactivity concentration (Bq/kg) data are presented in detail in Tables 1-4 under the following groupings: Table 1, foodstuffs; Table 2, waters; Table 3, rocks, soils and building materials; and Table 4, miscellaneous materials.
The tables show the radioactivity content by individual radionuclides and in terms of total alpha and beta/gamma content. The individual radionuclides have been classified according to those which are principally alpha-emitters and those which are beta or beta/gamma emitters. For concentrations less than l0 Bq/kg, only one significant figure has been quoted and for other values two significant figures have been quoted.
It is emphasised, for foodstuffs particularly, that the concentrations quoted are for the material 'as purchased', i.e. the values are not per kg 'dry weight'. It should be borne in mind that the water content of some items, e.g. vegetables, does vary and this may affect the concentration of radioactivity in the item.
During the literature search, a number of publications were found giving data on background radioactivity in foodstuffs and environmental materials in countries other than the UK. In the main, such data have not been used unless the foodstuff or material was one which is clearly commonly available in the UK (e.g. rice from India or mineral water from France) or was felt to be sufficiently similar to that in the UK. For example, values of 4°K in bread in the USA have been used but values for 21°pb in Japanese soils have not; this inevitably involves a degree of judgement.
Some of the concentrations in the tables have been derived from reported values of elemental potassium content (for 4°K) or elemental uranium content (for 238U) using the specific activity of the radionuclide in the natural element.
The following points should be noted with regard to the total concentra- tions presented in Tables 1-4.
(a) For many materials, a value for total alpha or total beta/gamma concentration has not been found in the literature. In such cases, the total alpha and beta/gamma values have been arrived at by summing the values for individual radionuclides where this is expected to be representative, i.e. where values for the most important radionuc- lides have been found. For example, 4°K usually contributes around 90% of the total beta/gamma content of foodstuffs (Suvakov et al., 1982), so that where a value of 4°K concentration has been found, the sum of individual beta/gamma radionuclides will be close to the
TA
BL
E
1 B
ackg
roun
d R
adio
acti
vity
in F
oods
tuff
s
Typi
cal
tota
l co
ncen
trat
ions
(r
ange
) (B
q/kg
)
Con
cent
ratio
ns o
f pri
ncip
al n
uclid
es
(ran
ge)
(Bq/
kg)
Alp
ha
Bet
a~ga
mm
a
Foo
ds
Alp
ha
Bet
a/
gam
ma
210p
o 22
0Ra
22
8T
h
238
U
14 C
4o
K
21°p
b R
efer
ence
s
Bre
ad
Cer
eals
Past
a
Ric
e
Mea
t (ex
c. p
oult
ry)
0.3-
5
3 (0
.3-2
1)
0,6
a
(0.0
2-1)
0-2
(0-0
4-0-
3)
63 a
100 ~
62 ~
62 a
100 ~
0.03
0.03
0-
03-0
-1
63
0-05
-3
2 0-
04
100
0.07
62
0-2
0.4
62
0-00
3~,)
-06
0-0
2 0
.03
100
0.09
T
urne
reta
l. (
1958
), M
orse
&
Wel
ford
(197
1),
de B
orto
li &
G
agli
one
(197
2),
Kle
men
t (1
982)
, Sm
ith-B
rigg
s &
B
radl
ey (1
984,
198
6)
0-08
T
urne
reta
l. (
1958
),S
mit
h&
Wat
son
(196
3/64
), H
amil
ton
(197
2),
Ren
ard
& Z
imm
erli
(1
984)
, Sm
ith-B
rigg
s &
B
radl
ey (1
984,
198
6)
0.03
M
orse
&W
elfo
rd(1
971)
,Wat
t &
Mer
rill
(197
5),
Kle
men
t (1
982)
0-
03
Mor
se&
Wel
ford
(197
1),
Ges
ell &
Low
der (
1980
),
Kle
men
t (19
82)
0.04
T
urne
reta
l. (
1958
),M
orse
&
Wel
ford
(197
1), d
e B
orto
li &
G
agli
one
(197
2),
Wat
t &
M
erri
ll (1
975)
, K
lem
ent
(198
2),
Smith
-Bri
ggs
&
Bra
dley
(198
4)
e~
,,,..i
(con
tinu
ed)
TA
BL
E I
---c
ontd
. I-
J
Typi
cal
tota
l co
ncen
trat
ions
(r
ange
) (B
q/kg
)
Con
cent
ratio
ns
of p
rinc
ipal
nuc
lide
s (r
ange
) (B
q/kg
)
Alp
ha
Bet
a~ga
mm
a
Foo
ds
Alp
ha
Bet
a/
gam
ma
21°p
o 22
6Ra
22ST
h 23
8 U
14(_
~ 40
K
Poul
try
10
0 a
0.
01-0
.04
1 O0
Mea
t pro
duct
s 0-
6 (s
ausa
ges,
bac
on,
(0.3
-0.7
) et
c.)
Off
al
4 ~
(0.2
-10)
75"
0.06
0.
01-0
.07
0-06
75
91 ̀+
4
(0.2
-10)
0.
007
0-09
90
Suga
rs a
nd p
rese
rves
0.
7 70
a 0-
02
0.02
-0-4
0.
07
Oils
and
fat
s 0-
4 7"
0.
009-
0-2
Spic
es
Tea
15
(13
-21)
80
" 60
0 ~
5 2
70
80
21op
b
0.04
().0
07
0.7
0-05
0.1
Ref
eren
ces
Mor
se &
Wel
ford
(19
71),
Wat
t &
Mer
rill
(19
75),
Kle
men
t (1
982)
, Sm
ith,
Bri
ggs
&
Bra
dley
(19
84)
Tur
ner
et a
l. (1
958)
, W
att
&
Mer
rill
(19
75),
Sm
ith-
Bri
ggs
&
Bra
dley
(i9
84,
1986
) T
urne
r et
al.
(195
8),
Hil
l (1
965)
. W
att
& M
erri
ll (
1975
),
Smit
h-B
rigg
s &
Bra
dley
(19
84.
1986
) T
urne
r et
al.
(195
8),
Kie
men
t (1
982)
, Sm
ith-
Bri
ggs
&
Bra
dley
(19
84,
1986
) T
urne
r et
al.
(195
8),
Wat
t &
M
erri
ll (
1975
), K
lem
ent
(198
2),
Smit
h-B
rigg
s &
B
radl
ey (
1984
) W
att
& M
erri
ll (
1975
) T
urne
r et
al.
(195
8),
Smit
h &
W
atso
n (1
963/
64),
Kle
men
t (1
982)
, L
alit
eta
l. (
1983
)
g~
TA
BL
E 1
--co
ntd.
Foo
ds
Typi
cal
tota
l C
once
ntra
tions
(r
ange
) (B
q/kg
)
Con
cent
ratio
ns o
f pri
ncip
al n
uclid
es
(ran
ge)
(Bq/
kg)
Alp
ha
Bet
a~ga
mm
a
Alp
ha
Bet
a/
gam
ma
21O
po
226R
a 22
STh
238 U
14
C
40 K
21
opb
Ref
eren
ces
Cof
fee
0.4
1 00
0 a
0.00
8 1
000
Win
e
Pot
atoe
s
Gre
en v
eget
able
s (f
resh
)
Roo
t veg
etab
les
(fre
sh)
Mus
hroo
ms
(dri
ed)
0"2
0-07
(u
p to
0" 1
~)
0.3
50 ~
(inc
. 20
3H
) 10
0 ~
0.00
4
30
0-00
7-0.
1 10
0 0.
02
(40-
240)
~
(0.0
2-3)
0-
01-0
-06
(40-
240)
0.04
13
0"
0-01
4).2
0.
03
130
530 c
' (i
nc.
311
137C
s )
222
(96-
392)
0-03
0-00
8
Tur
ner
etal
. (1
958)
, Wat
t &
M
erri
ll (
1975
), S
mit
h-B
rigg
s &
B
radl
ey (
1984
) de
Bor
toli
& G
agli
one
(197
2),
Ren
ard
& Z
imm
erli
(19
84)
Tur
ner
et a
l. (1
958)
, Mor
se &
W
elfo
rd (
1971
), K
lem
ent
(198
2),
Sm
ith-
Bri
ggs
&
Bra
dley
(19
84,
1986
) Sm
ith
& W
atso
n (1
963/
64),
H
ill (
1965
), S
cott
Rus
sell
(1
966)
, K
lem
ent
(198
2),
Sm
ith-
Bri
ggs
& B
radl
ey (
1984
)
Tur
ner
et a
l. (1
958)
, Sm
ith
&
Wat
son
(196
3/64
), H
ill (
1965
),
Sco
tt R
usse
ll (
1966
), M
orse
&
Wel
ford
(19
71),
Ham
ilto
n (1
972)
, K
lem
ent
(198
2)
Eck
l eta
l. (
1986
)
t~
',D
(con
tinu
ed)
TA
BL
E 1
---c
ontd
. ~ ~
.--
o
Typi
cal t
otal
co
ncen
trat
ions
(r
ange
) (B
q/kg
)
Con
cent
ratio
ns
of p
rinc
ipal
nuc
lide
s (r
ange
) (B
q/kg
)
Alp
ha
Bet
a~ga
mm
a
Bet
a/
Foo
ds
Alp
ha
gam
ma
2101
90
226R
a 22
8Th
278 U
]4
(,
,to K
2w
pb
Ref
eren
ces
Oth
er fr
esh
60
0.04
0-
04-4
).07
50
(I
-1)5
M
orse
& W
elfo
rd (1
971)
, de
ve
geta
bles
B
orto
li &
Gag
lion
e (1
9721
. (i
nclu
des
onio
ns,
Wat
t & M
erri
ll (
1975
), to
mat
oes)
K
lem
ent (
1982
), R
enar
d &
Z
imm
erli
(198
41, S
mit
h-B
rigg
s &
Bra
dley
(198
4, 1
986)
C
anne
d ve
geta
bles
60
" 0.
008-
0.06
6t
) {}
-(i12
M
orse
& W
elfo
rd (1
971)
, K
lem
ent (
1982
), Sm
ith-
Bri
ggs
& B
radl
ey (1
984)
M
ilk
0.7
40"
0-02
-0.2
0.
03-0
.01
40
0-03
T
urne
reta
l. (
1958
), Sm
ith
&
(0.0
4-0-
6)
Wat
son
(196
3/64
), H
ill (
1965
) ~
Mor
se &
Wel
ford
(197
1),
de
Bor
toli
& G
agli
one
(197
2),
Kle
men
t (19
82),
Smit
h et
al.
(198
4),
Srni
th-B
rigg
s &
B
radl
ey (1
984,
198
6)
Dai
ry p
rodu
cts
(inc
. 0.
5 30
~ 0.
04
0.01
-0.1
0-
06
30
(/.0
5 T
urne
reta
l. (
1958
), Sm
ith
&
crea
m, c
hees
e)
(0-~
-0.6
1 W
atso
n (1
963/
64),
Scot
t R
usse
ll (
1966
), K
lem
ent
(198
2),
Smit
h-B
rigg
s &
B
radl
ey (1
984,
198
6)
TA
BL
E l
-.-c
ontd
.
Typi
cal
tota
l co
ncen
trat
ions
(r
ange
) (B
q/kg
)
Foo
ds
Alp
ha
Con
cent
ratio
ns
of p
rinc
ipal
nuc
lide
s (r
ange
) (B
q/kg
)
Alp
ha
Bet
a~ga
mm
a
Bet
a/
gam
ma
21°p
o 22
6Ra
228T
h 23~
U
14 C
40
K
2lop
b R
efer
ence
s
Egg
s 0.
3 30
a 0.
1
Fres
h fr
uit
0.3
Frui
t pro
duct
s (i
nc.
0-4
juic
e, c
anne
d fr
uit)
(0
-3-1
)
Bea
ns
1
5O
(20
-10
0) ~
24
&
60
(30-
200)
a
0-05
q3.2
0-00
9~0.
02
0.02
0-0
3
0.02
~)-4
0-
02
0-2
3O
5O
(20-
100)
240 60
(30-
200)
0.07
T
urne
reta
l. (
1958
),S
mit
h&
~"
Wat
son
(196
3/64
), M
orse
&
~'
Wel
ford
(197
1), d
e B
orto
li &
~.
G
agli
one
(197
2),
Kle
men
t ,~
. (1
982)
, Sm
ith-
Bri
ggs
&
~.
Bra
dley
(19
84,
1986
) 0.
02
Tur
nere
tal.
(19
58),
Mor
se&
~.
W
elfo
rd (1
971)
, de
Bor
toli
&
Gag
lion
e (1
972)
, H
amil
ton
(197
2),
Kle
men
t (19
82),
Ren
ard
& Z
imm
erli
(198
4),
Smith
-Bri
ggs
& B
radl
ey
(198
4),
Eis
enbu
d (1
987)
~.
0.
08
Tur
nere
tal.
(19
58),
Sm
ith&
~"
W
atso
n (1
963/
64),
Mor
se &
W
elfo
rd (1
971)
, K
lem
ent
(198
2),
Smit
h-B
rigg
s &
B
radl
ey (1
984)
0-
03
Tur
ner e
tal.
(19
58),
Mor
se &
W
elfo
rd (1
971)
, K
lem
ent
(198
2)
(con
tinu
ed)
TA
BL
E l
---c
ontd
. -4
Typi
cal
tota
l co
ncen
trat
ions
(r
ange
) ¢B
q/kg
)
Con
cent
ratio
ns o
f pri
ncip
al n
uclid
es
(ran
ge)
(Bq/
kg)
Alp
ha
Bet
a~ga
mm
a
Bet
a/
Foo
ds
Alp
ha
gam
ma
:l°P
o 22
6Ra
228T
h 2~
8U 14
C
4°K
21
°pb
Ref
eren
ces
Fish
6-
200
110 a
6
0.00
9 0-
06
15
90
I). 2
(0
.007
-0-2
)
Shel
lfis
h/se
afoo
d 20
0 a
130 ~
20
0 0.
7-2
0-2
20
90
20
(100
-300
)
Bra
zil n
uts
200
250
50
40
200
(30-
700)
(3
-100
)
Oth
er n
uts
4 15
0 a
0-09
0-
3 15
0 0.
1
Tur
nere
tal.
(19
58),
Mor
se &
W
elfo
rd (
1971
), d
e B
orto
[i &
G
agli
one
(197
2),
Kle
men
t (1
982)
, Woo
dhea
d (1
982)
, Sr
nith
-Bri
ggs
& B
radl
ey (
1984
) T
urne
r et
al. (
1958
), H
ill
(196
5), M
orse
& W
elfo
rd
(197
1), K
lem
ent
(198
2),
McD
onal
d et
al.
(198
6)
Tur
ner
etal
. (19
58),
Sco
tt
Rus
sell
(19
66),
Pen
na-F
ranc
a et
al. (
1968
), G
abay
& I
rvin
g Sa
x (1
969)
, Kle
men
t (1
982)
, R
enar
d &
Zim
mer
li (
1984
) T
urne
r et
al.
(195
8),
Kle
men
t (1
982)
, Ren
ard
& Z
imm
erli
(1
984)
, S
mit
h-B
rigg
s &
B
radl
ey (
1984
)
'qnd
icat
es th
at a
tota
l al
pha
or to
tal
beta
/gam
ma
valu
e is
the
sum
of i
ndiv
idua
l al
pha
or b
eta/
gam
ma
nucl
ides
quo
ted
and
not a
mea
sure
d to
tal
Typ
ical
tota
l co
ncen
trat
ions
(r
ange
) (B
q/kg
)
TA
BL
E 2
B
ack
gro
un
d R
adio
acti
vit
y i
n V
ario
us
Wat
ers
Typ
ical
con
cent
ratio
ns o
f pri
ncip
al n
uclid
es
(ran
ge)
(Bq/
kg)
Alp
ha
Bet
a~ga
mm
a
Bet
a/
Wat
er
Alp
ha
gam
ma
Bot
tled
spa
wat
er
0"06
" (u
p to
1)
UK
dri
nkin
g w
ater
17
0 0-
04
(0.0
(0-8
00)
(0.0
2-0-
2)
UK
dri
nkin
g w
ater
4 a
so
urce
s (2
-11
) G
roun
dwat
er
2 Q (0
.9-3
)
UK
riv
ers
2 ~
7" (
2-11
)
21O
po
222R
n 22
6Ra
232T
h 23
4 U
238 U
0-02
0-
03--
1 0.
009
0.00
5
0-05
17
0 0.
2
2 0-
02
0.01
0-11
2
0-01
~H
WK
0"03
4 0.
01
(2-1
1)
2 (0
-9-3
) 0.
07
(o.o
.~o.
1)
7(2-
11)
0.1
(0-0
1-0-
3)
Sea
wat
er
0-1
12 ~
0-00
0 1
0.00
8 0.
002
0.05
0.
04
0.1
12
(up
to 0
-9)
87R
b 21
Opb
0"03
0"04
0.1
0.00
2
Ref
eren
ces
Pel
leri
n et
al.
(198
0), H
eske
th
(198
2), G
ans
(198
5)
Ken
ny e
t al.
(196
6)
Dep
t. o
f Env
iron
men
t (19
87)
Dep
t. o
f Env
iron
men
t (19
87)
Lab
. of G
over
nmen
t Che
mis
t (1
979)
, Hes
keth
(19
80,
1982
), D
ept.
of E
nvir
onm
ent (
1987
) C
herr
y &
Sha
nnon
(197
4),
UN
SC
EA
R (
1982
),
Woo
dhea
d (1
982)
, Bax
ter
(198
3)
Vin
dica
tes t
hat a
tota
l alp
ha o
r to
tal b
eta/
gam
ma
valu
e is
the
sum
of i
ndiv
idua
l alp
ha o
r be
ta/g
amm
a nu
clid
es q
uote
d an
d no
t a
mea
sure
d to
tal.
TA
BL
E 3
B
ack
gro
un
d R
adio
acti
vity
in
Var
ious
Roc
ks,
Soi
ls a
nd B
uild
ing
Mat
eria
ls
Typ
ical
tot
al
Con
cent
rati
ons
of p
rinc
ipal
co
ncen
trat
ions
nu
clid
es
(ran
ge)
(Bq/
kg)
Alp
ha
Bet
a/
Mat
eria
l A
lpha
ga
mm
a 22
6Ra
232T
h 23
8U
Bet
a/
gam
ma
"U' K
R
efer
ence
s
Roc
ks
Igne
ous
14(Y
' 80
0 ~
48
48
48
Gra
nite
17
fff
90
80
Sed
imen
tary
64
~ 33
0 ~
26
14
San
dsto
ne
Sed
imen
tary
95
" 80
0 ~
40
40
Sha
les
Lim
esto
nes
3&
8&
16
5 P
hosp
hate
ore
1
500 ~
26
0 ~
1 40
0 50
So
ils
Gen
eral
soi
l 55
0 44
(P
70
40
(300
-I 0
00)
(7-1
80)
(4--
I(X
))
Bri
cks
11~
60
(V
60
46
(7-1
70)
( 10-
1 00
0)
(2-9
0)
(3-8
0)
Gyp
sum
s an
d 33
0 °
90 ~
300
25
cem
ents
(3
0-80
0)
(40-
160)
(2
0-80
0)
(8-6
0)
Sand
s an
d gr
avel
s 20
0-2
000
3IY
4
20-2
00
24
15
15
Con
cret
es
90
500"
60
30
500
(4(I
-170
) (2
10--
650)
(7
-140
) (1
,3--
42)
(210
-560
)
8{X
) U
NS
CE
AR
(19
77),
Eis
enbu
d (1
987)
M
eggi
tt (
1983
) 33
0 U
NS
CE
AR
(19
77),
Eis
enbu
d (1
987)
80
0 E
isen
bud
(198
7)
80
Eis
enbu
d (1
987)
26
0 C
liff
et a
l. (1
984)
24
440
May
neor
d et
al.
(196
0),
Bow
en
(8-1
1(I)
(0
-2-1
200
) (1
979)
60
0 M
eggi
tt (
1983
1, C
liff
etaL
(1
0-1
000)
(1
984)
90
M
eggi
tt (
1983
), C
liff
etal
. (4
0-16
0)
(198
4)
20--9
11
30
May
neor
d et
al.
(196
0),
Meg
gitt
(19
83),
Cli
ffet
al.
(198
4)
Cli
ff e
t al.
(198
4)
L
'qnd
icat
es t
hat
a to
tal a
lpha
or
tota
l be
ta/g
amm
a va
hie
is th
e su
m o
f ind
ivid
ual
alph
a or
bet
a/ga
mm
a nu
ctid
es q
uote
d an
d qo
t a
mea
sure
d to
tal
TA
BL
E 4
B
ack
gro
un
d
Rad
iati
on
in
Mis
cell
aneo
us
Mat
eria
ls
Typi
cal
tota
l co
ncen
trat
ions
(r
ange
) ~B
q/kg
)
Bet
a/
Mat
eria
l A
lpha
ga
mm
a
Typi
cal
conc
entr
atio
ns o
f pri
ncip
al n
uclid
es
(ran
ge)
(Bq/
kg)
Alp
ha
Bet
a~ga
mm
a
"Wpo
22
4Ra
22~,
Ra
22
8T
h 2
30
Th
23
2Th
234 U
23
8 U
4o K
-'
topb
R
efer
ence
s
Hum
an o
rgan
s an
d I)
.2"
67 u
0.2
tiss
ues
(inc
. 7
mR
b)
Tob
acco
20
(0
-9 3
0)
0.00
3 0-
000
5 0.
000
2 0.
003
60
0.2
Boo
ks
30"
100 °
20
C
oal
Yor
ks 1
982
60 ~
300"
20
U
K 1
984
82"
170"
13
15
F
lyas
h 1
401I
'~ 1
100"
60
0 20
0 F
erti
lize
r "N
orm
al
2 20
0"
770
supe
rpho
spha
te'
'Con
cent
rate
d 4
600"
80
0 su
perp
hosp
hate
'
Gra
ss
12
300
Dri
ed
600"
10
100
20
20
300
13
12
15
14
170
2(X
I 21
X)
200
500
700
20
740
1 80
0 10
2
000
Sea
wee
d C
ornw
all
17"
0.2
0.04
9
8 G
uern
sey
4"
0.1
0.1
2 2
600
600
27
Ham
ilto
n (1
972)
, U
NS
CE
AR
(1
977,
198
21
Hil
l (19
65),
Sin
gh &
Nil
ekan
i (1
976)
La
lit e
t al.
(198
11
Sal
mon
(19
84)
Sal
mon
(19
84)
UN
SC
EA
R (
1982
)
UN
SC
EA
R (
1982
)
UN
SC
EA
R (
1982
)
Hil
l (1
965)
,Sm
ith-
Bri
ggs
(198
4)
Hi1
1(19
65),
Ren
ard
&
Zim
mer
li(1
984)
Cro
ss &
Day
( 1
981)
C
ross
& D
ay (
1981
)
"Ind
icat
es th
at a
tot
al a
lpha
or
tota
l be
ta/g
amm
a va
lue
is th
e su
m o
f ind
ivid
ual
alph
a or
bet
a/ga
mm
a nu
clid
es q
uote
d an
d no
t a
mea
sure
d to
tal.
276 P. R. Maul, ,I. P O'Hara
actual total beta/gamma concentration. Clearly these calculations are still likely to underestimate total concentrations.
(b) For some items, measurements have concentrated on a small number of specific radionuclides (for example 21°Po in the case of tobacco--See Table 4). In these cases, the actual total concentra- tions will undoubtedly be higher than those which would be obtained by summing over the radionuclides measured and, for this reason, total concentrations are not stated.
(c) In some instances, a value is quoted for total alpha or total beta/ gamma concentration which is significantly greater than the sum of individual radionuclide concentrations. This is due to the presence of radionuclides which have been detected in a total radioactivity measurement but which have not been measured or quoted separ- ately.
In the case of radionuclides from weapons-testing (principally the radionuclides 9°Sr and 137Cs), many publications have been produced giving measurements in the UK over the past 30 years. However, the levels of weapons-testing fallout radionuclides in the environment have declined generally since the peak of weapons testing in 1963-64, so data for these radionuclides have generally not been included in this compilation expli- citly, although residual levels of fallout radionuclides may be present in some of the measured total concentrations described in (c) above.
There are gaps in Tables 1-4 where data have not been found for particular nuclides in some foodstuffs and materials. Some examples of these are:
a4C in foodstuffs other than fish and seafood; beta/gamma activity in UK drinking water; 238U and a28Th in some foodstuffs, e.g. bread, potatoes and vegetables; alpha activity in groundwater; radionuclides in tobacco other than 2I°Po; and alpha-emitting nuclides in grass, other than 2a°Po.
T O T A L C O N C E N T R A T I O N S OF R A D I O A C T I V I T Y
The concentrations given in Tables 1-4 are indicative of the levels of radioactivity present in foodstuffs and other common environmental materials. These values may be compared with levels which are used to define 'radioactive substances' in the Radioactive Substances Act 1960 and Exemption Orders made under this Act.
For instance, the Radioactive Substances (Substances of Low Activity) Exemption Order 1986 exempts persons from registration under section 1
Radioactivity in environmental materials 277
TABLE 5 Classification of Materials According to Levels of Total Background Radioactivity
Total concentration (alpha + beta~gamma) (Bq/kg) a
Between 100 Bq/kg Less than 100 Bq/kg and 400 Bq/kg Greater than 400 Bq/kg
Bread Cereals Pasta Meat Rice Poultry Meat products Potatoes Offal Some green vegetables Sugars and preserves Root vegetables Oils and fats Some fresh fruit Spices Fruit products Wine Some beans Some green vegetables Fish Other fresh vegetables Some shellfish Canned vegetables Some Brazil nuts Milk Other nuts Dairy products Some UK drinking water Eggs Some rocks Some fresh fruit Some bricks Some beans Some gypsums Some UK drinking water Some concretes UK river water Cement Seawater Sands and gravels Some bricks Books Human organs and tissues Coal
Tea Coffee Dried mushrooms Some shellfish Some Brazil nuts Some UK drinking water Some rocks UK soils Some bricks Most gypsums Some concretes Flyash Fertilizers Dried grass
aFor details see Tables 1-4.
o f the R a d ioa c t i ve Subs tances Ac t 1960 ' in r espec t o f the k eep in g and use on any p remises o f solid r ad ioac t ive mate r ia l , o t h e r t han a c losed sou rce , which is subs tan t ia l ly inso luble in wa te r , the act ivi ty o f which does no t e x c e e d 0.4 b e c q u e r e l s pe r g ram ' . T h a t is, a solid insoluble ma te r i a l is e x e m p t if its act ivi ty is less t han 400 Bq/kg. U n d e r this def in i t ion a n u m b e r o f the mate r ia l s l is ted in the tables would no t be e x e m p t f r o m con t ro l u n d e r the R a d i o a c t i v e Subs tances Ac t , for e x a m p l e tea and co f fee , so m e bui ld ing mate r i a l s , fer t i l izers and some r o c k s .
T h e Ac t is m o r e explici t for some m e m b e r s of the na tu ra l ly occur r ing u r a n i u m and t h o r i u m series in tha t it def ines a subs tance as a ' r ad ioac t ive ma te r i a l ' if ( fo r solids) it con ta ins m o r e than:
740 Bq/kg lead; or 370 Bq/kg p o l o n i u m ; or 370 Bq/kg r ad ium; or
27~ t" R. Maul, J. P~ O'Hara
2590 Bq/kg thorium; or 11 100 Bq/kg uranium.
Under this definition, flyash would be a radioactive material (by virtue of its polonium content).
For comparative purposes, the foodstuffs and other environmental materials identified in the literature search have been grouped in Table 5 into three classifications; first those with total (alpha plus beta/gamma) concentration less than 100 Bq/kg, i.e. materials of very low radioactivity; secondly, those which have total concentration between 100 Bq/kg and 400 Bq/kg; and, thirdly, those materials which have a total concentration in excess of 400 Bq/kg. It should be noted that this grouping is for illustrative purposes only and does not relate to any potential radiological significance.
It should also be noted that some of these materials may be subject to large variations in water content and this can affect their concentration of radioactivity per unit mass.
A C K N O W L E D G E M E N T S
The authors wish to express their gratitude to E, J. Bradley of NRPB, Dr R. A. Mercer of NPL and Professor M. S. Baxter of the Scottish Universi- ties Research and Reactor Centre for sources of information used in the literature search and to Dr P. J. Coughtrey and Dr A. Phillips of ANS for useful discussions and comments . The paper is published with the permis- sion of the Central Electricity Generating Board.
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P, R. Maul Central Electricity Generating Board,
Sudbury House, 15 Newgate Street,
London EC1A 7AU, UK
& J. P. O'Hara* Associated Nuclear Services,
Eastleigh House, 60 East Street,
PO Box 67, Epsom, Surrey
KT17 1HA, UK
(Received 13 October 1988; revised version received 6 January 1989; accepted 13 January 1989) *Present address: Institution of Chemical Engineers, 166--71 Railway Terrace, Rugby CV21 3HQ, UK.