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Risks from naturally occurring radionuclides in the Nordic diet With focus on seafood and the NKS NANOD project
Mari Komperød (Stockholm, 16.01.2019)
Recent work in Norway:
• Report on radiation doses to the Norwegian public (all sources)
• Scientific paper on ingestion doses
• Risk assessment by Scientific Committee for Food Safety
Currently:
• NKS NANOD on natural radioactivity in fish and shellfish consumed in Nordic countries
Ingestion makes a significant contribution
Naturally occurring radionuclides cause majority of ingestion exposure, but receive little attention
External radiation
(terrestrial and building
materials)
Cosmic radiation
Other radionuclides in
air
[KATEGORINAVN]
[KATEGORINAVN]
Anthropogenic radionuclides
in diet
Average exposure from environmental sources in Norway
Average effective dose
Groups with elevated exposure
Radioactivity in food and drinking water can cause substantially higher doses for some
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
Average adult
High consumption of wild foodsfrom contaminated area
High seafood consumption
Air crew
High consumption of reindeerfrom contaminated area
High natural radioactivity indrinking water
High radon levels in indoor air
Dose (mSv/y)
External radiation (terrestrial andbuilding materials)Cosmic radiation
Other radionuclides in air
Rn-222 in air
Natural radioactivity in the diet
Anthropogenic radioactivity inthe diet
Average ingestion dose per radionuclide
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
⁴⁰K
*
²¹⁰P
o
²²²R
n
²²⁸R
a
²¹⁰P
b
¹³⁷C
s
¹⁴C
²²⁶R
a
²³⁰T
h
²³²T
h
²³⁴U
²²⁸T
h
²³⁸U
⁹⁰S
r
²³⁵U
⁹⁹Tc
Dose (
mS
v/y
ear)
Adults
Children
Infants
= Anthropogenic
*Constant 40K dose regardless of diet, due to homeostatic K regulation in the body (and constant 40K:K ratio)
Average dose per food group
Fish and shellfish
Drinking water
Plants and mushrooms
Meat
Other foodstuffs
Dairy products
Average dose by food category in Norway (minus 40K)
Fish and shellfish is the food group causing largest ingestion dose in several countries*
Due to relatively high levels 210Po and other natural radionuclides
*Assessments from e.g. Norway, France, Japan, UK
Ingestion doses
National estimates vary Partly due to differences in
intake of fish/shellfish
Little data on naturally occurring radionuclides in Nordic food
a. UNSCEAR 2008; b. Watson et al. 2005; Komperød &
Skuterud 2018; Renaud et al. 2015; Ota et al. 2009
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
UNSCEAR(a)
UK (b) Norway (c) France (d) Japan (e)
mS
v/y
Average ingestion dose from naturally occurring radionuclides
210Po in fish and shellfish
• 210Po binds to surfaces of particles, including plankton
• Primary route in fish/shellfish via diet
Organisms with diet consisting of e.g. plankton, bottom substrates etc. generally have highest concentrations
Plankton photomontage by Kils at Wikipedia.com CC 3.0.
(https://commons.wikimedia.org/wiki/File:Plankton_collage.jpg)
210Po in fish and shellfish
210Po varies considerably between species
Important to use species actually consumed when performing dose assessments!!
Examples (muscle / edible parts) Po-210
(Bq/kg fw)
Atlantic coda 0.35
Atlantic mackerelb 3.5
European pilchard (sardine)b 66
Blue musselsa 37
Lobsterc 62
Common periwinkle (snail)b 283
a. Dahlgaard 1995
b. Carvalho 2011
c. Rollo et al. 1992
NKS NANOD project
Natural Radioactivity in the Nordic Diet (NANOD)
Objective: More data to improve dose assessments for fish/shellfish and total diet in the Nordic countries
Partners
• Denmark: Technical University of Denmark (DTU)
• Sweden: University of Gothenburg (GU)
• Iceland: Icelandic Radiation Safety Authority (IRSA)
• Finland: Radiation and Nuclear Safety Authority (STUK)
• Norway: Norwegian Radiation and Nuclear Safety Authority (DSA)
NKS NANOD project
Consumption
data
Existing data
Expected high
levels
Sampling
~ 10 species in
each country
Analyses: 210Po, 210Pb, 226Ra, 228Ra
Results and
improved dose
assessments
Criteria
NKS NANOD - consumption
Total and species-specific consumption varies
Preferred fish species (> 5 g/d):
0
10
20
30
40
50
60
Denmark Finland Iceland Norway Sweden
Con
su
mp
tio
n g
/da
y
Fish
Shellfish
Denmark: Herring, tuna, mackerel
Finland: Salmon, trout
Iceland: Haddock, cod
Norway: Cod, salmon
Sweden: Cod, mackerel
Note: Large individual variation!
NKS NANOD - samples
Collected samples 2018
NKS NANOD – preliminary results 210Po
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Euro
pe
an
pla
ice
Atlan
tic
herr
ing
Atlan
tic
ma
cke
rel
Atlan
tic c
od
Hake
Saith
e
Hadd
ock
Atlan
tic
sa
lmo
n
Rain
bo
w t
rout
(farm
ed
)
Po
lon
ium
-21
0 in f
ish (
Bq/k
g f
w)
Baltic Sea
North Sea
Norwegian Sea
Kattegat/Skagerrak
0
10
20
30
40
50
60
70
80
90
Blu
e m
usse
l
Nort
hern
pra
wn
Bro
wn c
rab
Gre
at
sca
llop
Po
lon
ium
-21
0 in s
he
llfis
h (
Bq/k
g f
w)
Norwegian Sea
Kattegat/Skagerrak
NKS NANOD – preliminary results 210Po
Possible factors for variations within the same species:
• Location?
• Size?
• Season?
Uncertainties in assessing ingestion doses
• Representative values for activity concentration
• Reliable consumption data
• Dose coefficients (ICRP)
?
?
?
Uncertainties in assessing ingestion doses
Effect of food preparation?
By Superbass - Own work, CC BY-SA 4.0,
https://commons.wikimedia.org/w/index.php?curid=37744930
?
?
By Archangel12 - Normandy '10: Saint-Vaast-la-Hougue, CC BY 2.0,
https://commons.wikimedia.org/w/index.php?curid=31868904
Uncertainties in assessing ingestion doses
Delay from harvest until consumption
(210Po halflife = 138 days)
Lotus Head [GFDL
(http://www.gnu.org
/copyleft/fdl.html),
CC-BY-SA-3.0 via
Wikimedia
Commons ?
By Daniel Case,
CC BY-SA 3.0,
https://commons.wi
kimedia.org/w/inde
x.php?curid=58393
92
Nordic seafood in global market
> 10 % of fish export in world market
IAEA, FAO, WHO: joint project on guidelines for natural radioactivity
Already frequent requests for documentation of anthropogenic radionuclides – increased need for documentation of natural radionuclides in future?
By Strebe CC BY-SA 3.0 via Wikimedia Commons)
Summary
• Ingestion contributes a significant share of average dose, primarily through naturally occurring radiouclides
• For some, the ingestion dose is substantially higher
• Fish and shellfish is a major contributor to ingestion dose
• It is important to use species actually consumed
Way forward
NANOD: Remaining analyses, dose assessments and Final Report 2019
For improved dose assessments:
• More data on naturally occurring radionuclides in food
• Obtaining reliable consumption data (incl. percentiles)
• Futher examining effects of delay and food preparation on radionuclide levels