United Nations Scientific Committee on the Effects of Atomic Radiation

ATTACHMENT C-15

COMPILATION OF INGESTION DOSE RESULTSUNSCEAR 2013 Report, Annex A, Levels and effects of radiation exposure dueto the nuclear accident after the 2011 great east-Japan earthquake and tsunami,
Appendix C (Assessment of doses to the public)Content
This attachment describes the results of ingestion dose estimation for the public exposed toradiation from the accident at the Fukushima Daiichi nuclear power station (FDNPS) in
March 2011. The assessment was conducted for the UNSCEAR 2013 Report, although thispaper describing the detailed results was issued subsequently.
The population data were taken from the Japan Census [MIC, 2011].
Notes
The designations employed and the presentation of material in this publication do not imply theexpression of any opinion whatsoever on the part of the Secretariat of the United Nations
concerning the legal status of any country, territory, city or area, or of its authorities, orconcerning the delimitation of its frontiers or boundaries.
©

United Nations, January 2015. All rights reserved, worldwide.

This publication has not been formally edited.

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Contents
CONTENT ................................................................................................................................... 1
NOTES ......................................................................................................................................... 1
I. MAIN ASSESSMENT RESULTS ........................................................................................ 3
II. ADDITIONAL RESULTS FOR FIRST YEAR BASED ON DATABASE ON
ACTIVITY CONCENTRATIONS IN FOOD ....................................................................... 6
III. RESULTS OBTAINED USING FARMLAND MODEL AND MEASUREDDEPOSITION DENSITIES FOR JAPAN ........................................................................... 13
IV. VARIABILITY AND UNCERTAINTY IN ESTIMATED DOSES FROMINGESTION BASED ON MODELLING ........................................................................... 16
V. DOSES FROM INGESTION ESTIMATED FROM ATMOSPHERIC
TRANSPORT, DISPERSION AND DEPOSITION MODELLING .................................. 20
VI. DOSES FROM INGESTION OF MARINE FOODS.......................................................... 20
VII.

DOSES FROM DRINKING WATER ........................................................................... 22

VIII.

COLLECTIVE DOSES FROM INGESTION OF TERRESTRIAL FOODS ............... 25

REFERENCES ........................................................................................................................... 27

I.

MAIN ASSESSMENT RESULTS a

1.
The ingestion dose estimates for members of the public were derived from two primarysources. Dose estimates for the first year were based on the FAO/IAEA/MAFF database ofactivity concentrations in food (attachment C-8), while dose estimates for subsequent years
were based on the application of the FARMLAND model [Brown and Simmonds, 1995] tomeasured deposition rates to the ground. Doses were estimated for Fukushima Prefecture, thefive neighbouring or nearby prefectures combined (Chiba, Gunma, Ibaraki, Miyagi andTochigi) and for the rest of Japan; in each case three age groups were considered and effective
doses and equivalent doses to the thyroid and red bone marrow were calculated. Account was
taken of the restrictions on food supplies introduced by the Japanese authorities. These dose
estimates were subsequently combined with estimates of doses due to other exposure pathways
to obtain the total estimated doses for the representative individuals of the public with average
dietary habits.
aPlease note throughout this compilation, although results are given to two or three significant figures, this degreeof precision do not imply such a level of accuracy for the estimated doses, which are considerably more uncertain.

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

Table 1. Ingestion doses for characteristic individuals in Fukushima Prefecture
Values in brackets assume only 25% consumed is locally marketed
Age group
Time period

Infant (1-year old)Child (10-year old)

Adult

Effective
dose (mSv)

Absorbed doseto thyroid (mGy)

Effective
dose (mSv)

Absorbed dose tothyroid (mGy)

Effective
dose (mSv)

Absorbed dose tothyroid (mGy)

1 year

1.90 (0.61)

32.8 (10.0)

1.16 (0.39)

15.2 (4.7)

0.94 (0.32)

7.78 (2.3)

10 year

1.96

32.9

1.24

15.3

1.01

7.86

Lifetime

2.00

32.9

1.27

15.4

1.04

7.89

Age group
Time period

Infant (1-year old)Child (10-year old)

Adult

Absorbed dose to
red bone marrow (mGy)

Absorbed dose to
red bone marrow (mGy)

Absorbed dose to
red bone marrow (mGy)

1 year

0.23 (0.09)

0.36 (0.14)

0.55 (0.20)

10 year

0.28

0.43

0.63

Lifetime

0.31

0.46

0.66

Table 2. Ingestion doses for characteristic individuals in 5 prefectures (Chiba, Gunma, Ibaraki,
Miyagi and Tochigi) neighbouring Fukushima Prefecture
Values in brackets are assume only 25% consumed is locally marketed
Age group
Time period

Infant (1-year old)Child (10-year old)

Adult

Effective
dose (mSv)

Absorbed doseto thyroid (mGy)

Effective
dose (mSv)

Absorbed dose tothyroid (mGy)

Effective
dose (mSv)

Absorbed dose tothyroid (mGy)

1 year

0.53 (0.27)

9.38 (4.3)

0.31 (0.18)

4.34 (1.96)

0.21 (0.13)

2.11 (0.92)

10 year

0.55

9.40

0.33

4.36

0.22

2.13

Lifetime

0.55

9.40

0.33

4.37

0.23

2.13

Age group
Time period

Infant (1-year old)Child (10-year old)

Adult

Absorbed dose to
red bone marrow (mGy)

Absorbed dose to
red bone marrow (mGy)

Absorbed dose to
red bone marrow (mGy)

1 year

0.05 (0.05)

0.08 (0.07)

0.10 (0.09)

10 year

0.07

0.10

0.12

Lifetime

0.07

0.10

0.12

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Table 3. Ingestion doses for characteristic individuals in the rest of JapanAge group
Time period

Infant (1-year old)Child (10-year old)

Adult

Effective
dose (mSv)

Absorbed doseto thyroid (mGy)

Effective
dose (mSv)

Absorbed doseto thyroid (mGy)

Effective
dose (mSv)

Absorbed dose tothyroid (mGy)

1 year

0.18

2.57

0.13

1.17

0.11

0.53

10 year

0.19

2.58

0.14

1.17

0.11

0.53

Lifetime

0.19

2.58

0.14

1.17

0.11

0.53

Age group
Time period

Infant (1-year old)Child (10-year old)

Adult

Absorbed dose to
red bone marrow (mGy)

Absorbed dose to
red bone marrow (mGy)

Absorbed dose to
red bone marrow (mGy)

1 year

0.05

0.07

0.09

10 year

0.05

0.07

0.09

Lifetime

0.05

0.07

0.09

2.

The following should be noted for tables 1 to 3:(a) The use of two decimal places does not imply this degree of accuracy;(b) All doses include the effects of ageing on the dose estimation, i.e., the lifetime dose for
adult (assumed to be 20 years old at the time of the accident) was for a period of
60 years, for the 10-year old child it was for a period of 70 years and for a 1-year-old
infant it was for a period of 80 years; this assumed average length of life was 80 years;(c) All dose estimates included the effects of food restrictions (simulated using the
FARMLAND model) or were for foods as marketed (based on the FAO/IAEA/MAFF
database);(d) The first year dose estimates were based on the values from the database on activity
concentration in food and any food that was not marketed was assumed not to be
consumed in the region of interest. The additional ingestion doses for subsequent years
were estimated based on modelling from measured deposition densities and assume that
25% of food consumed was locally produced and 75% was produced elsewhere in
Japan. The values in brackets for the first year show the effect of assuming that 25% of
the food consumed was locally produced in the assessment of doses using the database.
In all cases account was taken of the amount of particular foods that were imported into
Japan;(e) Dose estimates did not include contributions from ingestion of drinking water, which isconsidered separately below.

3.

The following points could be noted:− Effective doses for one-year-olds were up to about a factor of two higher than thecalculated doses for adults, with doses for 10-year-old children in between these twovalues;− Absorbed doses to the thyroid were about a factor of 4 higher for the one-year-old thanthe calculated doses for adults;

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS− Estimated doses for Fukushima Prefecture were about a factor of 4 higher than those
calculated for the 5 neighbouring prefectures and a factor of 10 higher than those for the
rest of Japan;− Nearly the entire estimated dose was delivered in the first year, with little increase in
the estimate after integration over 10 years or over a lifetime;− The main doses presented in tables 1 to 3 for the first year assumed that the foodsampled was representative of the food eaten in the prefecture and no allowance wasmade for a proportion of the food being consumed from elsewhere in Japan. If, as forthe dose assessment based on modelled activity concentration in food, it was assumed
that only 25% of food was locally produced and the remaining 75% was from the restof Japan, then the dose estimates would be lower. The estimates for the first year’s
doses assuming that 25% of food only is locally marketed are given in brackets intables 1 and 2 above.

II.

ADDITIONAL RESULTS FOR FIRST YEAR BASED ONDATABASE ON ACTIVITY CONCENTRATIONS IN FOOD

4.
Using the database of activity concentrations in food, ingestion doses were calculated
as a function of time for the first year following the accidental releases from FDNPS for arange of organs and age groups. The full results are given in the following tables, all based onfood marketed in the location of interest allowing for the proportion of each food type that is
imported into Japan.
5.

The following points could be noted in relation to table 4:− The doses from ingestion in the first month following the accident contributed the
major part of the doses for the first year. For example, for infants, over 90% of the firstyear’s effective dose was delivered in the first month and for adults, over 80% of theeffective dose was delivered in the first month.
− The doses for each month after the first month were all significantly lower than thedoses for the first month and showed some fluctuation from month to month. The
values for months 2 to 4 and then for 5 to 12 were essentially the same given theuncertainties in the dose assessment. Variations would be expected that reflect theuncertainties in the measurement data combined with some variability depending on
which foods were produced at different times. However, of more importance is likely tobe the use of a constant value of 10 Bq/kg for measurements below the limits ofdetection. This value was used for 131I, 134Cs and 137Cs for the first four months
following the accident, but only for the two caesium isotopes after 4 months; this wasprobably the reason for the observed reduction in doses in the fifth and subsequentmonths, particularly for the absorbed dose to the thyroid.
− These results also reflect the impact of the restrictions on food supplies because theproducts from the areas most affected by the accident were excluded from the market
and these would likely have been above limits of detection and therefore showed thegreatest variation with time.

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Table 4. Ingestion doses for the first year following the accident based on the database ofactivity concentrations in food — results for Fukushima Prefecture
OrganTime after theaccident

1st month

2nd month

3rd month

4th month

5th month

6th month

Absorbed to organ (Gy) or Effective dose (Sv)Infant (1-year old)
-4Child (10-year old)
3.97 × 10

Adult

-4

5.23 × 10-4

Lower large intestine wall

4.32 × 10

Colon

3.37 × 10-4

3.49 × 10-4

4.82 × 10-4

Red bone marrow1.61 × 10-4

2.59 × 10-4

4.15 × 10-4

Lungs

1.70 × 10-4

2.58 × 10-4

4.02 × 10-4-2-2

7.42 × 10-3

Thyroid3.12 × 10

1.45 × 10

Effective dose

1.74 × 10-3

1.01 × 10-3

7.85 × 10-4

Lower large intestine wall

1.58 × 10-5

1.40 × 10-5

1.53 × 10-5-5-5

1.41 × 10-5

Colon

1.23 × 10

1.23 × 10

Red bone marrow

5.95 × 10-6

9.12 × 10-6

1.21 × 10-5

Lungs

6.25 × 10-6

9.08 × 10-6

1.18 × 10-5

-4

-4

9.13 × 10-5

Thyroid

5.37 × 10

2.35 × 10

Effective dose

3.37 × 10-5

2.15 × 10-5

1.66 × 10-5

Lower large intestine wall

1.78 × 10-5

1.51 × 10-5

1.74 × 10-5

Colon

1.39 × 10-5

1.33 × 10-5

1.60 × 10-5

-6-6

1.38 × 10-5

Red bone marrow6.70 × 10

9.85 × 10

Lungs

7.03 × 10-6

9.81 × 10-6

1.34 × 10-5

Thyroid5.26 × 10-4

2.30 × 10-4

8.95 × 10-5

Effective dose

3.41 × 10-5

2.20 × 10-5

1.81 × 10-5

Lower large intestine wall

2.01 × 10-5

1.78 × 10-5

2.32 × 10-5

Colon

1.57 × 10-5

1.57 × 10-5

2.14 × 10-5

Red bone marrow

7.56 × 10-6

1.16 × 10-5

1.84 × 10-5

-6-5

1.78 × 10-5

Lungs

7.94 × 10

1.16 × 10

Thyroid

5.00 × 10-4

2.20 × 10-4

8.93 × 10-5

Effective dose

3.37 × 10-5

2.33 × 10-5

2.26 × 10-5

Lower large intestine wall

1.17 × 10-5

1.02 × 10-5

1.05 × 10-5

Colon

9.16 × 10-6

8.95 × 10-6

9.69 × 10-6-6-6

8.35 × 10-6

Red bone marrow

4.46 × 10

6.65 × 10

Lungs

4.67 × 10-6

6.62 × 10-6

8.08 × 10-6

Thyroid5.36 × 10-6

7.11 × 10-6

8.37 × 10-6

Effective dose

5.45 × 10-6

7.16 × 10-6

8.62 × 10-6

Lower large intestine wall

1.70 × 10-5

1.51 × 10-5

1.65 × 10-5

Colon

1.33 × 10-5

1.33 × 10-5

1.52 × 10-5

-6-6

1.31 × 10-5

Red bone marrow

6.47 × 10

9.87 × 10

Lungs

6.77 × 10-6

9.83 × 10-6

1.27 × 10-5

Thyroid7.62 × 10-6

1.05 × 10-5

1.31 × 10-5

Effective dose

7.91 × 10-6

1.06 × 10-5

1.35 × 10-5

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

OrganTime after theaccident

Lower large intestine wall

Months 7 to 9

Months 10 to 12

Total dose in thefirst year

6.

Absorbed to organ (Gy) or Effective dose (Sv)Infant (1-year old)Child (10-year old)Adult

4.45 × 10-5

3.85 × 10-5

4.12 × 10-5-5-5

3.79 × 10-5

Colon

3.48 × 10

3.39 × 10

Red bone marrow

1.69 × 10-5

2.52 × 10-5

3.27 × 10-5

Lungs

1.77 × 10-5

2.51 × 10-5

3.17 × 10-5

Thyroid1.99 × 10-5

2.68 × 10-5

3.27 × 10-5

Effective dose

2.07 × 10-5

2.71 × 10-5

3.37 × 10-5

Lower large intestine wall

4.87 × 10-5

4.21 × 10-5

4.55 × 10-5-5-5

4.19 × 10-5

Colon

3.80 × 10

3.70 × 10

Red bone marrow

1.84 × 10-5

2.75 × 10-5

3.61 × 10-5

Lungs

1.93 × 10-5

2.74 × 10-5

3.50 × 10-5

Thyroid2.17 × 10-5

2.92 × 10-5

3.61 × 10-5-5-5

3.72 × 10-5

Effective dose

2.25 × 10

2.96 × 10

Lower large intestine wall

6.08 × 10-4

5.49 × 10-4

6.92 × 10-4

Colon

4.74 × 10-4

4.83 × 10-4

6.38 × 10-4

-4

-4

5.49 × 10-4

Red bone marrow

2.27 × 10

3.59 × 10

Lungs

2.40 × 10-4

3.58 × 10-4

5.32 × 10-4

Thyroid3.28 × 10-2

1.52 × 10-2

7.78 × 10-3

Effective dose

1.90 × 10-3

1.16 × 10-3

9.35 × 10-4

The following points could be noted in relation to table 5:− Again the dose for the first month was the major contributor to the overall dose for all
age groups and organs but this was slightly less marked than for Fukushima Prefecture.
For example, for infants, over 70% of the first year’s effective dose was due toingestion in the first month, while, for adults, this fraction was just less than 50%. Thisdifference might reflect the lower levels of activity concentration in measured
foodstuffs outside Fukushima Prefecture, and hence the substitution of a measurement
value of less than the limit of detection with an assumed value of 10 Bq/kg (thisassumption that the minimum concentration was given as the lower detection limit iscalled ‘MDL assumption’ hereafter) affects a larger proportion of measurements, andhence the implied dose.
− The same pattern in dose beyond 4 months was seen for these prefectures as for
Fukushima Prefecture, probably reflecting the inference that for after 4 months allmeasurements of 131I less than limits of detection were considered to be zero rather than
10 Bq/kg.

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Table 5. Ingestion doses for the first year following the accident based on the database ofactivity concentrations in food — results for 5 prefectures neighbouring Fukushima Prefecture
OrganTime after theaccident

1st month

2nd month

3rd month

4th month

5th month

6th monthMonths 7 to 9

Absorbed to organ (Gy) or Effective dose (Sv)Infant (1-year old)
-5Child (10-year old)
1.11 × 10

Adult

-5

1.13 × 10-5

Lower large intestine wall

1.55 × 10

Colon

1.17 × 10-5

9.56 × 10-6

1.03 × 10-5

Red bone marrow

4.91 × 10-6

6.93 × 10-6

8.85 × 10-6

Lungs

5.47 × 10-6

7.08 × 10-6

8.58 × 10-6

-3

-3

1.79 × 10-3

Thyroid

7.81 × 10

3.62 × 10

Effective dose

3.95 × 10-4

1.95 × 10-4

9.97 × 10-5

Lower large intestine wall

8.19 × 10-6

6.97 × 10-6

6.55 × 10-6

-6-6

6.04 × 10-6

Colon

6.39 × 10

6.14 × 10

Red bone marrow

3.06 × 10-6

4.55 × 10-6

5.20 × 10-6

Lungs

3.23 × 10-6

4.54 × 10-6

5.04 × 10-6

Thyroid4.91 × 10-4

2.13 × 10-4

8.34 × 10-5-5-5

9.35 × 10-6

Effective dose

2.81 × 10

1.57 × 10

Lower large intestine wall

9.58 × 10-6

8.13 × 10-6

7.79 × 10-6

Colon

7.46 × 10-6

7.16 × 10-6

7.18 × 10-6

-6-6

6.18 × 10-6

Red bone marrow

3.58 × 10

5.31 × 10

Lungs

3.77 × 10-6

5.30 × 10-6

5.98 × 10-6

Thyroid5.45 × 10-4

2.35 × 10-4

8.71 × 10-5-5-5

1.05 × 10-5

Effective dose

3.14 × 10

1.76 × 10

Lower large intestine wall

8.95 × 10-6

7.64 × 10-6

7.19 × 10-6

Colon

6.98 × 10-6

6.73 × 10-6

6.63 × 10-6

Red bone marrow

3.35 × 10-6

4.99 × 10-6

5.71 × 10-6

-6

-6

5.53 × 10-6

Lungs

3.53 × 10

4.98 × 10

Thyroid4.92 × 10-4

2.12 × 10-4

7.67 × 10-5

Effective dose

2.85 × 10-5

1.61 × 10-5

9.51 × 10-6

Lower large intestine wall

8.76 × 10-6

7.67 × 10-6

7.55 × 10-6

-6-6

6.96 × 10-6

Colon

6.86 × 10

6.77 × 10

Red bone marrow

3.34 × 10-6

5.03 × 10-6

6.00 × 10-6

Lungs

3.50 × 10-6

5.01 × 10-6

5.81 × 10-6-6-6

6.00 × 10-6

Thyroid3.93 × 10

5.34 × 10

Effective dose

4.08 × 10-6

5.41 × 10-6

6.19 × 10-6

Lower large intestine wall

1.41 × 10-5

1.24 × 10-5

1.39 × 10-5-5-5

1.28 × 10-5

Colon

1.10 × 10

1.09 × 10

Red bone marrow

5.36 × 10-6

8.12 × 10-6

1.11 × 10-5

Lungs

5.62 × 10-6

8.09 × 10-6

1.07 × 10-5

-6

-6

1.11 × 10-5

Thyroid6.32 × 10

8.63 × 10

Effective dose

6.56 × 10-6

8.74 × 10-6

1.14 × 10-5

Lower large intestine wall

3.85 × 10-5

3.40 × 10-5

3.71 × 10-5

Colon

3.02 × 10-5

3.00 × 10-5

3.43 × 10-5-5-5

2.95 × 10-5

Red bone marrow

1.47 × 10

Lungs

1.54 × 10-5

2.22 × 10-5

2.86 × 10-5

Thyroid1.73 × 10-5

2.37 × 10-5

2.95 × 10-5-5-5

3.04 × 10-5

Effective dose

1.79 × 10

2.23 × 10

2.40 × 10

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

OrganTime after theaccident

Lower large intestine wall

Months 10 to 12

Total dose in thefirst year

Infant (1-year old)Child (10-year old)Adult

3.66 × 10-5

3.23 × 10-5

3.44 × 10-5-5-5

3.17 × 10-5

Colon

2.87 × 10

Red bone marrow

1.40 × 10-5

2.12 × 10-5

2.73 × 10-5

Lungs

1.46 × 10-5

2.11 × 10-5

2.64 × 10-5

Thyroid1.64 × 10-5

2.25 × 10-5

2.73 × 10-5-5-52.85 × 10

2.82 × 10-5

Effective dose

1.71 × 10

Lower large intestine wall

1.40 × 10-4

1.20 × 10-4

1.26 × 10-4

Colon

1.09 × 10-4

1.06 × 10-4

1.16 × 10-4

-5-5

2.28 × 10

9.98 × 10-5

Red bone marrow

5.22 × 10

Lungs

5.51 × 10-5

7.82 × 10-5

9.66 × 10-5

Thyroid9.38 × 10-3

4.34 × 10-3

2.11 × 10-3

-4

-42.05 × 10-4

Effective dose

7.

Absorbed to organ (Gy) or Effective dose (Sv)

5.29 × 10

7.84 × 10

3.05 × 10

The following points could be noted in relation to table 6:− Again the dose received in the first month was the major contributor to the overall dose
for all age groups and organs, but this is less marked than in Fukushima Prefecture. For
example, for infants, over 30% of the first year’s effective dose was from ingestion in
the first month while for adults this was less than 20%. This difference probably
reflected the lower levels measured outside Fukushima Prefecture and hence theemployment of the MDL assumption as a greater proportion of measurements were lessthan the limit of detection and were ascribed an assumed value of 10 Bq/kg value.
− The same change in monthly effective dose beyond 4 months was seen as for
Fukushima Prefecture and the neighbouring prefectures. This reflects the inference thatafter 4 months all measurements of 131I that were less than the limits of detection wereconsidered to be 0 rather than 10 Bq/kg, and this finding is borne out by considering thedoses for other organs. For example, doses to the thyroid were two orders of magnitude
greater in months 1 to 4 than in month 5. As 131I was the major contributor to thethyroid dose, this was not surprising. After month 5 the dose to the thyroid was very
similar to the value for the dose to all other organs, which reflected the uniform
distribution of radiocaesium in the body. For other organs the step change in dose from4 to 5 months was not seen to any extent, which is consistent with the doses being due
to the caesium isotopes, for which the MDL assumption (i.e., adoption of 10 Bq/kg as
the minimum concentration) continued to be used.
− The possible impact of the inference can be seen by considering the potential dose if all
food had been consumed with the limit of detection value. Allowing for the foodimports and only including 131I for the first four months then the total effective dose to a
one year old in a year could be 0.21 mSv with the dose to the thyroid being 2.9 mGy.
These estimates include rice but it is known that rice was not harvested in the earlymonths following the accident. If rice is excluded completely then the annual doses to a
one year old decrease to 2 mGy to the thyroid (due to 131I only) and 0.15 mSv effective
dose (summed for the three radionuclides). For comparison with the tables above themonthly thyroid dose due to 131I at 10 Bq/kg is estimated to be 0.5 mGy without rice
(0.725 mGy with rice) while the monthly effective dose in the first four months would
be 0.029 mSv (summed for the three radionuclides) without rice and for the last

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11

8 months would be 0.0058 mSv per month from the two caesium isotopes with rice.
These doses are slightly higher than the doses presented in the tables above for the restof Japan as they assume that all food is contaminated at the 10 Bq/kg level but showthat the estimated doses beyond the first month are significantly affected by theassumption that all reported measurements at or below the limit of detection are treatedas 10 Bq/kg.
Table 6. Ingestion doses for first year following the accident based on the database of activity
concentrations in food — results for the rest of Japan
Organ

Time after theaccident

1st month

2nd month

3rd month

4th month

5th month

6th month

Absorbed to organ (Gy) or Effective dose (Sv)Infant (1-year old)
-6

Child (10-year old)
7.85 × 10

Adult

-6

7.29 × 10-6

Lower large intestine wall

9.52 × 10

Colon

7.39 × 10-6

6.90 × 10-6

6.71 × 10-6

Red bone marrow

3.48 × 10-6

5.10 × 10-6

5.78 × 10-6-6

-6

5.60 × 10-6

Lungs

3.70 × 10

5.11 × 10

Thyroid1.17 × 10-3

5.28 × 10-4

2.38 × 10-4

Effective dose

6.24 × 10-5

3.26 × 10-5

1.78 × 10-5

Lower large intestine wall

8.13 × 10-6

6.86 × 10-6

6.27 × 10-6

Colon

6.34 × 10-6

6.05 × 10-6

5.78 × 10-6

Red bone marrow

3.05 × 10-6

4.49 × 10-6

4.98 × 10-6

-6

-6

4.82 × 10-6

Lungs

3.22 × 10

4.48 × 10

Thyroid4.69 × 10-4

2.03 × 10-4

7.81 × 10-5

Effective dose

2.70 × 10-5

1.51 × 10-5

8.86 × 10-6

-6-6

6.68 × 10-6

Lower large intestine wall

8.54 × 10

7.17 × 10

Colon

6.66 × 10-6

6.31 × 10-6

6.16 × 10-6

Red bone marrow

3.20 × 10-6

4.68 × 10-6

5.31 × 10-6

Lungs

3.37 × 10-6

4.67 × 10-6

5.13 × 10-6

-4

-4

7.68 × 10-5

Thyroid4.84 × 10

2.08 × 10

Effective dose

2.79 × 10-5

1.56 × 10-5

9.12 × 10-6

Lower large intestine wall

8.57 × 10-6

7.39 × 10-6

6.82 × 10-6-6-6

6.30 × 10-6

Colon

6.69 × 10

6.51 × 10

Red bone marrow

3.22 × 10-6

4.83 × 10-6

5.42 × 10-6

Lungs

3.39 × 10-6

4.82 × 10-6

5.25 × 10-6

Thyroid4.10 × 10-4

1.77 × 10-4

6.73 × 10-5-5-58.75 × 10-6

Effective dose

2.42 × 10

1.41 × 10

Lower large intestine wall

8.17 × 10-6

7.09 × 10-6

6.64 × 10-6Colon

6.40 × 10-6

6.25 × 10-6

6.13 × 10-6

-6

-6

5.28 × 10-6

Red bone marrow

3.12 × 10

4.65 × 10

Lungs

3.26 × 10-6

4.63 × 10-6

5.11 × 10-6

Thyroid3.93 × 10-6

5.02 × 10-6

5.31 × 10-6

Effective dose

3.82 × 10-6

5.01 × 10-6

5.45 × 10-6

-5-6

8.48 × 10-6

Lower large intestine wall

1.01 × 10

8.71 × 10

Colon

7.83 × 10-6

7.58 × 10-6

7.75 × 10-6

Red bone marrow

3.74 × 10-6

5.60 × 10-6

6.69 × 10-6-6-6

6.51 × 10-6

Lungs

3.90 × 10

5.57 × 10

Thyroid

4.37 × 10-6

5.93 × 10-6

6.69 × 10-6

Effective dose

4.57 × 10-6

6.02 × 10-6

6.86 × 10-6

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

OrganTime after theaccident

Absorbed to organ (Gy) or Effective dose (Sv)Infant (1-year old)Child (10-year old)Adult

3.57 × 10-5

3.15 × 10-5

3.26 × 10-5-5-5

3.01 × 10-5

Lower large intestine wall

Months 7 to 9

Months 10 to 12

Total dose in thefirst year

Colon

2.80 × 10

2.78 × 10

Red bone marrow

1.36 × 10-5

2.07 × 10-5

2.59 × 10-5

Lungs

1.43 × 10-5

2.06 × 10-5

2.51 × 10-5

Thyroid1.61 × 10-5

2.20 × 10-5

2.59 × 10-5-5-5

2.67 × 10-5

Effective dose

1.67 × 10

2.23 × 10

Lower large intestine wall

3.61 × 10-5

3.19 × 10-5

3.30 × 10-5

Colon

2.83 × 10-5

2.81 × 10-5

3.04 × 10-5-5-5

2.62 × 10-5

Red bone marrow

1.38 × 10

2.09 × 10

Lungs

1.44 × 10-5

2.08 × 10-5

2.54 × 10-5

Thyroid1.63 × 10-5

2.22 × 10-5

2.62 × 10-5-5-5

2.71 × 10-5

Effective dose

1.69 × 10

2.25 × 10

Lower large intestine wall

1.25 × 10-4

1.09 × 10-4

1.08 × 10-4

Colon

9.76 × 10-5

9.56 × 10-5

9.94 × 10-5

Red bone marrow

4.72 × 10-5

7.10 × 10-5

8.56 × 10-5-5-5

8.29 × 10-5

Lungs

4.96 × 10

7.07 × 10

Thyroid2.57 × 10-3

1.17 × 10-3

5.25 × 10-4

Effective dose

1.83 × 10-4

1.33 × 10-4

1.11 × 10-4

8.
An analysis was also carried out to determine which foods and radionuclides
contributed to the doses. This was complicated, because of the way that the database results
were used to assess the doses and because results were only available for the different periodsin the year that were considered and not for the year as a whole. The breakdown by food typewas also only available for each radionuclide separately. The following table shows thecontribution of the different radionuclides to the effective doses in Fukushima Prefecture forparticular periods for the three age groups considered.
Table 7. Percentage contribution of different radionuclides to effective doses from ingestion in
Fukushima Prefecture based on the database of measurement results
Time period

Infants (1-year old)
131

I

134

Cs

Adults
137

131

134

137

Cs

I

Cs

Cs

Month 1

88.9

6.3

4.8

45.7

32.2

22.1

Month 4

72.8

15.2

12.0

16.1

48.5

35.4

Month 6

0

55.7

44.3

0

57.7

42.3

Months 10–12

0

54.5

45.5

0

56.4

43.6

9.
The differences in contributions for the different age groups is because of differences in
the relative magnitudes of the dose coefficients for the three radionuclides with age, as well as— to a lesser extent — differences in the diets with age. In all cases 131I was the main
contributor to dose in the first four months, but then owing to radioactive decay (and theassumptions on limits of detection) its contribution became negligible. The slightly higher
contribution of 134Cs was because of its higher dose coefficient than that for 137Cs, but theeffect was slightly reduced with time owing to the faster radioactive decay of 134Cs (initiallythere were roughly equal proportions of the two radionuclides).

ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

13

10.
The contribution of different foods to effective dose was only available for eachradionuclide, age group and time period separately. The following table gives some illustrative
results to show the contribution of the major foods at different times.
Table 8. Percentage contribution of different foods for each radionuclide to effective doses fromingestion in Fukushima Prefecture based on the database of measurement results
Infants (1-year old)Time
periodKey foods

Adults

131

134

137

131

134

137

I

Cs

Cs

I

Cs

Cs

Month 1

Leafy vegetables
Root and other vegetables

73.1
25.0

84.8
13.6

85.1
13.4

77.1
21.8

87.5
11.7

87.7
11.5

Month 4

Milk
Crustacea and molluscs
All vegetables
Fruit

38.5
1.9
32.6
6.8

16.4
41.4
15.5
7.8

15.5
42.4
15.0
8.1

15.1
3.9
49.3
6.3

4.3
57.2
15.8
4.9

4.1
57.9
12.2
5.0

Month 6

Milk
Mushrooms
All vegetables
Rice

No dose

19.7
15.7
17.6
21.9

18.6
17.7
16.9
21.2

No dose

6.3
20.2
21.5
26.5

5.9
22.5
20.6
25.3

Months
10–12

Fruit
Milk
All vegetables
Rice

No dose

8.3
20.8
31.7
23.3

9.3
18.6
34.2
21.7

No dose

6.5
6.9
38.7
29.1

7.1
6.1
40.9
26.8

11.
Different foods contributed at different times with various types of vegetables
contributing relatively significantly to the dose for both age groups at all times. For 6 months
and later rice was an important contributor to the total dose, reflecting its importance in theJapanese diet and the fact that nearly all rice consumed in Japan was produced in Japan[MAFF, 2012]. Crustaceans were important for only a limited period, while the contribution
from fish was very variable from month to month, being greater for the caesium radioisotopes
than for those of iodine and making a minor contribution overall. In the database considerable
attention had been paid to concentrations of radionuclides in beef, but the contribution to thedoses from ingestion of beef were relatively small. Milk was a significant contributor to dose,particularly for 1-year-old infants and for 131I, except in the first month after the releases; thisfitted with the known agricultural practices, where in March cows are kept indoors and given
stored feed, which would have had relatively low levels of activity.

III. RESULTS OBTAINED USING FARMLAND MODEL AND
MEASURED DEPOSITION DENSITIES FOR JAPAN12.
The primary set of results assumed that restrictions on food consumption had beensuccessful and that for domestically produced food, 25% had been locally produced with theremaining 75% coming from the rest of Japan. The proportion of imported food was based on
2010 national data and imported food was [MAFF, 2012] considered to have no activity.
Results are available for each prefecture of Japan where measurements of deposition density
were available. Tables 9 to 11 give the calculated ingestion doses for Fukushima Prefecture,
the average range for the five neighbouring prefectures, and the average for the rest of Japan,
for comparison with the results based on the FAO/IAEA/MAFF database. The results beyond
the first year were used to develop tables 1 and 3. Tables 12 to 14 give the same set of results,
but for absorbed dose to the thyroid.

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

Table 9. Effective doses from ingestion for characteristic individuals in Fukushima Prefecture,
based on the FARMLAND model and measured deposition densities with and without
restrictions
Effective dose (mSv) for each age groupTime
periodInfant (1-year old)Child (10-year old)

Adult

With
restrictions

No
restrictions

With
restrictions

No
restrictions

With
restrictions

No
restrictions

1 year

0.10

6.40

0.076

3.48

0.061

2.00

10 years

0.17

6.50

0.16

3.61

0.14

2.10

Lifetime

0.20

6.53

0.19

3.64

0.17

2.13

Table 10. Effective doses from ingestion for characteristic individuals in the five neighbouring
prefectures, based on the FARMLAND model and measured deposition densities with andwithout restrictions
Effective dose (mSv) for each age groupTime
periodInfant (1-year old)With
restrictions

Child (10-year old)No
restrictions

With
restrictions

No
restrictions

Adult
With
restrictions

No
restrictions

1 year

0.12

0.70

0.080

0.40

0.057

0.25

10 years

0.13

0.72

0.10

0.42

0.074

0.26

Lifetime

0.14

0.72

0.11

0.43

0.080

0.27

Table 11. Effective doses from ingestion for characteristic individuals in the rest of Japan, basedon the FARMLAND model and measured deposition densities with and without restrictions
Effective dose (mSv) for each age groupTime
periodInfant (1-year old)Child (10-year old)

Adult

With
restrictions

No
restrictions

With
restrictions

No
restrictions

With
restrictions

No
restrictions

1 year

0.038

0.074

0.025

0.043

0.016

0.027

10 years

0.040

0.076

0.028

0.046

0.018

0.029

Lifetime

0.041

0.076

0.028

0.046

0.019

0.030

Table 12. Absorbed dose to the thyroid from ingestion for characteristic individuals inFukushima Prefecture, based on the FARMLAND model and measured deposition densities withand without restrictions
Thyroid dose (mGy) for each age groupTime
periodInfant (1-year old)With
restrictions

No
restrictions

Child (10-year old)With
restrictions

Adult

No
restrictions

With
restrictions

No
restrictions

1 year

1.49

120

0.71

55.6

0.35

27.6

10 years

1.55

120

0.79

55.8

0.43

27.7

Lifetime

1.58

120

0.82

55.8

0.46

27.7

ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

15

Table 13. Absorbed dose to the thyroid from ingestion for characteristic individuals in thefive neighbouring prefectures, based on the FARMLAND model and measured deposition
densities with and without restrictions
Thyroid dose (mGy) for each age groupTime
periodInfant (1-year old)Child (10- year old)

Adult

With
restrictions

No
restrictions

With
restrictions

No
restrictions

With
restrictions

No
restrictions

1 year

1.82

12.6

0.86

5.89

0.44

2.94

10 years

1.83

12.6

0.88

5.91

0.45

2.96

Lifetime

1.84

12.6

0.89

5.92

0.46

2.96

Table 14. Absorbed dose to the thyroid from ingestion for characteristic individuals in the rest ofJapan, based on the FARMLAND model and measured deposition densities with and without
restrictions
Thyroid dose (mGy) for each age groupTime
periodInfant (1-year old)With
restrictions

No
restrictions

Child (10-year old)With
restrictions

No
restrictions

Adult
With
restrictions

No
restrictions

1 year

0.63

1.31

0.29

0.61

0.14

0.31

10 years

0.63

1.31

0.30

0.62

0.14

0.31

Lifetime

0.63

1.31

0.30

0.62

0.15

0.31

13.

The following points can be noted in relation to the results in tables 9 to 14:(a) The introduction of restrictions on food supplies had a significant impact on theestimated doses. For example, in Fukushima Prefecture for a 1-year-old infant, theeffective dose due to ingestion in the first year would have been 6.4 mSv without
restrictions, but if the restrictions had been completely introduced then this would havebeen reduced to 0.1 mSv. For the more distant prefectures there was still a reduction in
the estimated doses because of the restrictions, but this was less marked than for
Fukushima Prefecture (e.g. a reduction of about a factor of two in the effective dose to a
1-year old child in the rest of Japan);(b) The doses estimated for the first year using the modelling approach and assuming
restrictions were completely effective were lower than the doses estimated using thedatabase. However, the estimated doses assuming no restrictions in Fukushima
Prefecture were significantly higher than the doses based on the measurement database.
For example, for a 1-year-old infant in Fukushima Prefecture the estimated effective
dose using the database was 1.9 mSv, using the model the estimated dose was 0.1 mSv
assuming full restrictions and 6.4 mSv assuming no restrictions. For the fiveneighbouring prefectures the corresponding results were: 0.53, 0.12 and 0.7 mSv,
respectively, while for the rest of Japan they were: 0.18, 0.038 and 0.074 mSv,
respectively. There are a number of different factors that may have lead to thesedifferences;(c) The main contribution to the doses estimated from the database of measurements wasfrom intakes of 131I in the first month, particularly for Fukushima Prefecture. However,there were limited numbers of these early measurements and attention had beennecessarily focussed on the areas with highest deposition densities where restrictions
were or might have been required. This could have led to some overestimation of doses

16

ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

from ingestion based on measurements, because levels of radionuclides in food fromother areas would have been lower;(d) The database does contain some measurements in marketed foods that were above thelevels introduced for restrictions because it was not possible to make these completely
effective in the early period after the accident. This leads to higher estimated doses
from the database than from the modelling where restrictions were assumed to becompletely effective;(e) For areas away from Fukushima Prefecture assuming that all measurements at or below
limits of detection were 10 Bq/kg is likely to have overestimated the actual levels andhence doses. If it were assumed that all foods eaten had 10 Bq/kg of 131I for the first
four months and 10 Bq/kg of both 134Cs and 137Cs throughout the year then theestimated effective doses for a 1-year-old infant would have been between 0.15 and0.21 mSv depending on whether rice was included in the estimate. This result is similar
to the doses obtained using the database and indicates that they might be overestimates.
14.
The estimated doses for the first year based on modelling were not used in the main
assessment for combining with the estimated doses from other pathways. However, theestimated doses for beyond the first year based on modelling were used and are included intables 1 to 3. The increase in integrated doses from 1 to 10 years or over a lifetime was
generally small. For the thyroid doses the lifetime dose was virtually all delivered in the firstyear following the accident. The increase in the integrated dose was greatest for effective doses
in Fukushima Prefecture when restrictions were taken into account. This is because theestimated dose for the first year was significantly reduced. The increase in the integrated dose
was a factor of two to three over a lifetime. Without restrictions the first year’s dose provided
most of the lifetime dose. This was particularly the case for the thyroid dose to a 1-year-old
infant in Fukushima Prefecture where the doses for the first year, integrated to 10 years andover a lifetime were estimated to be the same if restrictions were not applied.

IV. VARIABILITY AND UNCERTAINTY IN ESTIMATED DOSES FROMINGESTION BASED ON MODELLING
15.
For the standard modelling results presented in section III it was assumed that 25% offood was from the prefecture where the individual lived and 75% from elsewhere in Japan;
allowance was also made for foods being imported into Japan. Results were also obtained for
Fukushima Prefecture assuming that 100% of the food was locally produced both with andwithout allowing for imported food. The effect of this on adult effective doses is seen intable 15.
Table 15. Adult effective doses for Fukushima Prefecture assuming 100% of food is locally
produced (using modelling approach)
Adult effective dose (mSv) with food restrictions values without restrictions in brackets

Time
(a)

Standard result: 25% local

100% local but allowing for imports

100% local no allowance for imports

1 year

0.061 (2.0)

0.20 (7.91)

0.27 (12.8)

10 years

0.14 (2.1)

0.50 (8.33)

1.38 (14.0)

Lifetime

0.17 (2.13)

0.62 (8.45)

1.55 (14.2)

16.
Assuming all foods consumed (but allowing for imports) were produced locallyincreased the estimates of adult effective doses by about a factor of 4 when restrictions aretaken into account. If no allowance was made for food imports, the increase in estimated doses

ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

17

was up to a factor of 9 for lifetime doses with a smaller effect in the first year. This reflects anincreased estimated dose in each year when more locally produced food is assumed to be eaten.
If restrictions on food supplies were not taken into account then there was still a significant
increase in the estimated doses at all times. In Japan, the vast majority of people eat food fromsupermarkets which would have been sourced and distributed throughout Japan and which
would contain significant amounts of imported produce [MAFF, 2012]. Therefore, the above
dose estimates do not apply to characteristic individuals. However, some individuals might
have consumed food that they produced themselves or obtained locally and their doses mighttheoretically approach the values shown above. Table 16 gives similar results for infant thyroid
doses in Fukushima Prefecture showing the effects of assuming 100% local food consumption.
For doses to the thyroid the contribution from the dose in the first year was dominant and so
only the first year results were estimated assuming greater local food consumption.
Table 16. Absorbed doses to thyroid for infants in Fukushima Prefecture assuming 100% of foodis locally obtained (using modelling approach)
Time
(a)

Infant thyroid dose (mGy) with food restrictions values without restrictions in brackets
Standard result: 25% local

100% local but allowing for imports

100% local no allowance for imports

1 year

1.49 (119)4.07 (474)4.97 (587)

10 years

1.55 (119)--Lifetime

1.58 (120)

-

-

17.
It should be recognized that in addition following the accident many people avoided
produce from Fukushima Prefecture or even from Japan, and for these individuals the doses
from ingestion would have been much lower than those given above and for some would havebeen effectively zero.
18.
It took a few days for food restrictions to be introduced in Japan and so it is possiblethat people did eat food above the restriction levels during this time. However, the accident
occurred in March and so there was very limited fresh produce available, and livestock would
have been kept indoors and fed on stored feed. The possible exception is that some types ofgreen vegetables, for example spinach, would have been growing at that time and people could
have eaten their own vegetables from the garden. This possibility has been examined byconsidering the effect on the modelled doses of assuming that restrictions were not introduced
until 7 days after the time of deposition for two locations in Fukushima Prefecture: Iitate
village in the extended evacuation zone and Koriyama City, which is outside the evacuation
areas. Tables 17 and 18 show the results for adult effective doses and infant thyroid doses,
respectively.
Table 17. Adult effective doses in Iitate village and Koriyama city, assuming restrictions did notoccur until 7 days after deposition and only local produce was consumed (based on modelling)
Adult effective dose (mSv) (with food restrictions)Time (d)Bans implemented from 0 days
IitateKoriyama

Bans implemented from 7 days
IitateKoriyama

7

0.00

0.00

11.0

1.82

365

0.57

0.15

11.6

1.97

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

Table 18. Infant thyroid doses in Iitate village and Koriyama city, assuming restrictions did notoccur until 7 days after deposition and only local produce is consumed (based on modelling)
Infant thyroid dose (mGy) (with food restrictions)Time (d)Bans implemented from 0 days
IitateBans implemented from 7 days

Koriyama

IitateKoriyama

7

0.00

0.00

731

123

365

0.33

0.08

732

123

19.
At both locations considered, there would be a significant increase in estimated doses if
local food had been eaten in the first 7 days following the time of deposition, confirming theimportance of intakes in the early period after deposition. However, it should be recognizedthat this is a very cautious estimate because it is assumed that all of the vegetables eaten are
freshly produced, which is unlikely. Also the model assumes that the vegetables would havebeen in the open and so there would have been deposition directly onto the edible portions. The
Committee understands that at this time, in Iitate village, for example, vegetables were likely tohave been grown in greenhouses or were protected from frost and snow by being covered withsoil. For both these situations, levels of radionuclides in the vegetables would have beensignificantly lower than assumed here. Nevertheless, this analysis shows that it is possible thatsome individuals could have received considerably higher doses than the characteristic doses
assessed in the main study.
20.
The contribution of the different radionuclides and foods to the ingestion doses would
have varied with location and time, and on whether restrictions were effective. Some
illustrative results for Iitate village and Koriyama City making different assumptions are givenin the following tables.
Table 19. Contribution of three radionuclides to adult effective doses from ingestion in Iitate
municipality (inside extended evacuated area) with and without food restrictions

Contribution to adult effective dose (with food restrictions)

Time
131

I (%)

134

Cs (%)

137

Cs (%)

Total dose (Sv)

7 days---0.00 × 10+00

1 year

0.1

54.8

45.2

5.69 × 10-4

60 years

0.0

42.5

57.4

7.52 × 10-3

Time

Contribution to adult effective dose (without food restrictions)
131

I (%)

134

Cs (%)

137

Cs (%)

Total dose (Sv)

7 days

80.8

11.3

7.9

1.10 × 10-2

1 year

31.3

38.1

30.6

4.81 × 10-2

60 years

26.8

38.7

34.5

5.62 × 10-2

ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

19

Table 20. Contribution of three radionuclides to adult effective doses from ingestion in Koriyama
municipality (south-west of evacuated area) with and without food restrictions
Contribution to adult effective dose (with food restrictions)

Time

131

I (%)

134

Cs (%)

137

Cs (%)

Total dose (Sv)

7 days---0.00 × 10+00

1 year

0.0

56.2

43.8

1.48 × 10-4

60 years

0.0

43.6

56.4

1.29 × 10-3

Contribution to adult effective dose (without food restrictions)
Time

131

I (%)

134

Cs (%)

137

Cs (%)

Total dose (Sv)

7 days

82.5

10.3

7.1

1.82 × 10-3

1 year

33.8

36.8

29.4

7.50 × 10-3

60 years

29.1

37.6

33.3

8.72 × 10-3

Table 21. Contribution of different foods to adult effective doses from ingestion in Iitate
municipality (inside evacuated area) with and without food restrictions
Contribution to adult effective dose (with food restrictions)Time
Rank 1 (%)

Rank 2 (%)

Rank 3 (%)

Total dose (Sv)

7 days---0.00 × 10+00

1 year

Potatoes (49.3)

Green vegetables (37.2)

Rice (12.4)

5.69 × 10-4

60 years

Grain (58.9)

Green vegetables (10.3)

Pork (9.8)

7.52 × 10-3

Contribution to adult effective dose (without food restrictions)Time
Rank 1 (%)

Rank 2 (%)

Rank 3 (%)

Total dose (Sv)

7 daysGreen vegetables (100)--1.10 × 10-2

1 yearGreen vegetables (47.3)

Grain (34.0)

Pork (5.6) / Milk (5.3)

4.81 × 10-2

60 years

Green vegetables (41.5)

Grain (37.0)

Pork (6.1) / Milk (5.7)

5.62 × 10-2

Table 22. Contribution of different foods to adult effective doses from ingestion in Koriyama
municipality (south-west of evacuated area) with and without food restrictions
Contribution to adult effective dose (with food restrictions)Time
Rank 1 (%)

Rank 2 (%)

Rank 3 (%)

Total dose (Sv)

7 days---0.00 × 10+00

1 yearGreen vegetables (63.8)

Potatoes (28.4)

Rice (7.1)

1.48 × 10-4

60 years

Grain (51.7)

Green vegetables (13.9)

Pork (8.6)

1.29 × 10-3

Contribution to adult effective dose (without food restrictions)Time
Rank 1 (%)

Rank 2 (%)

Rank 3 (%)

Total dose (Sv)

7 daysGreen vegetables (100)--1.82 × 10-2

1 yearGreen vegetables (49.2)

Grain (32.8)

Pork (5.4) / Milk (5.2)

7.50 × 10-3

60 years

Green vegetables (43.3)

Grain (35.5)

Pork (5.9) / Milk (5.5)

8.72 × 10-3

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

21.
The effect of the restrictions is marked for both locations and demonstrates that the
restrictions would have essentially removed all of the contribution of 131I from the estimateddoses and also the initial contribution of green vegetables to the total dose from ingestion. The
results in tables 19 to 22 are broadly consistent with the results in tables 7 and 8 above for thedoses derived from the database for the first year after the accident.
22.
The results above show the importance of the estimated levels of 131I in green
vegetables in the first week or so following the accidental releases. Table 23 below shows theestimated peak activity concentrations of 131I in green vegetables at Koriyama City and Iitate
village according to the FAO/IAEA/MAFF database. These levels are well above the limits
used by the Japanese authorities to introduce restrictions on food supplies and are the sameorder as some measurements reported for vegetation in the period shortly after the releases.
Table 23. Peak activity concentration of iodine-131 in green vegetables in key locations
Activity concentration in green vegetables (Bq kg-1)
Iitate village
3.4 × 10

5

Koriyama City
5.6 × 104

V. DOSES FROM INGESTION ESTIMATED FROM ATMOSPHERIC
TRANSPORT, DISPERSION AND DEPOSITION MODELLING
23.
The FARMLAND model results were also used with values for deposition densities
derived from the estimated source term and atmospheric transport, dispersion and deposition
modelling (ATDM) results (attachment C-9). For Fukushima Prefecture the estimated effective
and thyroid doses were generally a factor of 2 to 3 times higher than those based on themeasured deposition densities, with some lower ratios because of the effects of foodrestrictions. These differences demonstrate the known tendency of the atmospheric dispersion
results to overestimate the measured deposition densities in many locations in Fukushima
Prefecture. In addition, the ingestion dose results for a number of prefectures distant from
Fukushima Prefecture were zero because the atmospheric dispersion results predicted nosignificant deposition. This also applied to the nearby countries where no significant deposition
was predicted. Therefore, the Committee considered that the results based on the ATDM weresuch that no further analysis should be undertaken of these estimated ingestion doses.

VI. DOSES FROM INGESTION OF MARINE FOODS24.
The estimated doses from ingestion of radionuclides in marine foods are included in theestimated doses derived from the database for the first year following the accident. Their
contribution to the total dose was assessed to be not greater than 10% overall (see table 8
above). This reflects the restrictions put in place on seafood from Fukushima Prefecture.
25.
Using predictions of the levels of 137Cs in seawater over the next 10 years [Nakano andPovinec, 2012] and beyond based on experience of fallout from nuclear weapons testing in the
middle of the twentieth century, it was possible to make very rough predictions of futureradiation doses from ingestion of seafood. The predictions in table 24 are given to two
significant figures but this is for computational reasons and as elsewhere this degree of
accuracy should not be implied.

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21

Table 24. Predicted effective doses to different age groups from consumption of radionuclides
in marine foods at various times after accident in 2011
Time after the accident (a)Annual effective dose to different age groups (Sv/a)
Infant (1-year old)
-8Child (10-year old)

Adult

2

1.4 × 10

2.1 × 10

3.9 × 10-8

5

3.1 × 10-9

4.3 × 10-9

8.2 × 10-9

10

1.2 × 10-9

1.7 × 10-9

3.2 × 10-920

8.6 × 10-10

1.2 × 10-9

2.3 × 10-9

50

-10

-10

8.1 × 10-10

3.1 × 10

4.3 × 10

-8

26.
These estimated effective doses are all very low and are less than the doses that havebeen estimated from ingestion of terrestrial foods, even 2 years after the accident. This isbecause of the significant dilution of caesium in the ocean water, which leads to very low
concentrations of radiocaesium in seawater and therefore in the marine food away from theimmediate area of the FDNPS site. Concentrations of radiocaesium in marine food are
predicted to be less than 0.1 Bq/kg two years after the accident, which is 100 times less than
the 10 Bq/kg assumed for the first year in the main dose assessment when concentrations were
below detection limits. This creates an artificial gap between the doses assessed for the firstyear, which might be significantly overestimated, in particular for the last few months of thefirst year when a lot of measurements were below detection limits. However, at the end of thefirst year, measurements were reported for some fish species that were still significantly above
detection limits, which is believed to result from the biological half-life of the radioactive
material in these fish species. For those fish species, the concentrations might beunderestimated by the present method, at least two years after the accident. Nevertheless, therestrictions still in place ought to prevent such marine foods reaching the market. In later years
it is likely that the concentrations in seawater will tend to decrease more slowly and be
homogeneous over large areas, reducing the potential for locally high values.
27.
Before the accident, the concentration of 137Cs in the western North Pacific Ocean was
about 1 to 2 mBq/L. In other words, the impact of the releases from FDNPS became rapidly
negligible at the scale of the North Pacific Ocean compared to the pre-existing levels from theatmospheric nuclear weapons tests. The reason is the enormous input of 137Cs from the tests;
the inventory was assessed to be about 69 PBq before the accident [Aoyama et al., 2012],
which can be compared with the releases from the accident, assessed as a few petabecquerels
by most authors (see appendix B).
28.
The concentration factors used to estimate the doses are typical of marine foodcategories, namely algae, fish and crustaceans/molluscs. However, it is known that different
species show different concentration factors, e.g. pelagic fish compared to benthic fish or
crustacean compared to molluscs. The modelling results for 137Cs dispersion in seawater are
given for surface waters of the ocean. The levels may be inhomogeneous on the vertical scale
and the concentrations in the marine food may differ from results derived from surface watermodelling.
29.
The current dose assessment method assumed that concentrations of radionuclides inthe seawater was homogeneous in the North Pacific Ocean. Results of the dispersion models
showed that the activity levels exhibit local significant horizontal gradients, at least during thefirst years after the accident.

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

30.
There are several sources of uncertainty and the main ones are discussed here. One of
the main sources is in the estimate for the amount of 137Cs discharged into the sea from the
FDNPS site. To avoid these uncertainties, the dispersion model is understood to have used themeasured concentration of this radionuclide at the release point [Bailly du Bois et al., 2012,213] as a "boundary condition" in the grid cell where such point is located in the computational
mesh. Kawamura et al. [Kawamura et al., 2011] assumed that the observed concentration at theoutlet extended over an area of 1.5 km2 in front of the plant. Since the grid cell surface is larger
than 1.5 km2, a correction factor was introduced to ensure that the total activity in the release
grid cell was the same as if the discharge was homogeneous over a 1.5 km2 area. Given theshallow waters at the outlet point, it was also assumed that the 137Cs concentration there wasvertically homogeneous. These assumptions are likely to be sources of uncertainty for thisassessment, but they are hard to quantify. Another source of uncertainty is the deposition onto
seawater of radiocaesium released to the atmosphere. However, Periáñez et al. [Periáñez et al.,2012] showed that direct releases to the sea dominated those from atmospheric deposition on
the surface and this source of uncertainty should be limited. Another factor is the interaction of
caesium with sediment. The dispersion model included processes such as radioactive decay,
adsorption and desorption of radionuclides by suspended matter, settling to the seabed andresuspension of sediments. The interactions with suspended matter and seabed sediment aresources of uncertainty. The sediment will be a long-term source of 137Cs remobilizing in themarine environment. Periáñez et al. [Periáñez et al., 2012] derived the half-time of 137Cs in thesediment from the assessment of the total inventory of this nuclide in the sediment of the area
close to FDNPS where the concentrations were higher. They estimated a half-time of 167 days,a value of the same order of magnitude as the 137Cs half-time for the sediment in the English
Channel derived using the same kind of water/sediment interaction model. This secondary
source of radiocaesium therefore is expected to become negligible after a few years and thus
not considered to be a major long-term source of uncertainty.

VII. DOSES FROM DRINKING WATER
31.
The Committee's assessment of doses from drinking water was based on measurements
carried out in a number of locations. The doses from drinking water depended on the source of
the water, the degree of treatment of the water supply and any measures taken to restrict
supplies or provide alternate sources of water. The Committee's assessment was based on theavailable measurement data and took account of the restrictions applied. Doses were estimatedfor specific locations and a population-weighted dose was also estimated for Fukushima
Prefecture. Some districts within Fukushima Prefecture were evacuated following the accident
and therefore no measurement data were available for these locations. No attempt was made toestimate doses for these districts and the citizens of these districts were excluded from the
population-weighted averages. Table 25 below shows the range of estimated doses for
Fukushima Prefecture.
Table 25. Range of estimated effective and thyroid doses to a characteristic individual drinking
water from Fukushima Prefecture
Infant (1-year old)Child (10-year old)

Adult

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Effective dose (Sv)0.00 × 10+00

4.79 × 10-4

0.00 × 10+00

1.94 × 10-4

0.00 × 10+00

1.65 × 10-4

Thyroid dose (Sv)0.00 × 10+00

9.57 × 10-3

0.00 × 10+00

3.72 × 10-3

0.00 × 10+00

3.20 × 10-3

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23

32.
In each case the maximum dose was assessed to be to people living in Iitate village. A
further analysis was carried out for Iitate as shown below. However, in this case the results
were decay-corrected assuming that drinking water levels would have been elevated from thetime that the radioactive plume was overhead on 16 March 2011. This slightly increases theestimates of dose as shown in table 26.
Table 26. Estimated effective and thyroid doses for Iitate Village allowing for decay correction
Dose (Sv)Infant (1-year old)Child (10-year old)

Adult

Total effective dose

7.80 × 10-4

3.10 × 10-4

2.63 × 10-4

Total thyroid dose

1.56 × 10-2

5.95 × 10-3

5.12 × 10-3

33.

Assumptions used in the above calculation:− Drinking water restrictions were followed. For Iitate these were in place from 21 March
to 10 May (infants) and 21 March to 1 April 2011 (adults).
− The first recorded measurements of water were taken on 20 March 2011. Modelling
data shows the plume passed over Iitate on 15 March 2011. Therefore concentrations ofradionuclides in water for 16 March to 19 March were estimated using theconcentration in water measured on 20 March and correcting for radioactive decay.
− To back-calculate 132I concentrations, it was assumed that 132I was in equilibrium with132
Te on 20 March 2011. The decay correction was applied using the 132Te half life.

34.
The estimated adult effective doses from drinking water were slightly less than theestimated doses from ingestion of terrestrial foods in Iitate village assuming that locally
produced food is eaten but that restrictions were in place (see table 17) and significantly lower
than the effective doses from ingestion of terrestrial foods if it was assumed that locally
produced vegetables were eaten in the first week following the accident. For infants, the doseto the thyroid from drinking water was estimated to be higher than the dose due to ingestion of
locally produced food if restrictions were applied, but significantly less than the possible
thyroid doses if infants ate green vegetables in the first week following the deposition. Thisfurther illustrates that there would have been significant variability in the doses received in
Iitate Village depending on the behaviour of the individuals. As well as estimating ingestion
doses at specific locations a population-weighted dose from ingestion of drinking water was
also calculated and the results are given in table 27.
Table 27. Estimated population-weighted, median, minimum and maximum doses for Fukushima
Prefecture due to drinking water

Doses

Effective dose (Sv)(all radionuclides)

Thyroid dose (Gy)(all radionuclides)

Infant(1-year old)Child
(10-year old)

Adult

Infant(1-year old)Child
(10-year old)

Adult

Population-weighted

5.63 × 10-5

2.82 × 10-5

2.46 × 10-5

1.12 × 10-3

5.34 × 10-4

4.60 × 10-4

Median (districts)

2.55 × 10-6

9.84 × 10-7

1.37 × 10-6

4.76 × 10-5

1.76 × 10-5

1.52 × 10-5

Minimum (district)

0.00 × 10+00

0.00 × 10+00

0.00 × 10+00

0.00 × 10+00

0.00 × 10+00

0.00 × 10+00

Maximum (district)

4.79 × 10-4

1.94 × 10-4

1.65 × 10-4

9.57 × 10-3

3.72 × 10-3

3.20 × 10-3

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ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

35.
The estimated population-weighted dose from drinking water is small compared withthe estimated dose from ingestion of food (table 1). For example for a 1-year-old infant in thefirst year the estimated effective dose from ingestion of food was 1.9 mSv and the weighted
dose from ingestion of drinking water was 0.056 mSv. However, for some districts thecontribution was more significant, although still less than the estimated dose from ingestion offoods. The main results included in the overall dose assessment therefore do not include any
contribution from drinking water.
36.
Two papers reported average doses from drinking water to Japanese citizens. Murakami
and Oki [Murakami and Oki, 2012] estimated absorbed doses to the thyroid from a number ofpathways including ingestion of drinking water for citizens of Tokyo for the year following the
Fukushima accident. Amano et al. [Amano et al., 2012] estimated committed effective doses
due to inhalation and ingestion of tap water in the two months directly following the accident
for Chiba residents. A comparison of these results with the dose estimated in this assessment isgiven in table 28. The doses estimated for adults and infants in both papers show good
agreement with those estimated here. Doses to children do not agree as well. This may be dueto the use of different ingestion dose coefficients for children. This report uses dosecoefficients for a 10-year-old child. Murakami and Oki [Murakami and Oki, 2012] havedefined a child as being aged 0–9 years old while Amano et al. [Amano et al., 2012] define achild as aged 2–7 years. Therefore it is possible that dose coefficients for a 1- or 5-year oldhave been used for these calculations. There are also slight variations in the start and end datefor dose estimates that may have made a difference to the final results.
Table 28. Comparison of doses calculated in this assessment to those in published literature foringestion of drinking waterWith restrictions – Tokyo
Reference

Average absorbed dose to the thyroid (mSv)
Infant (1-year old)Child (10-year old)

Adult

Murakami and Oki[Murakami and Oki, 2012]

0.47

0.54

0.19

This assessment

0.54

0.21

0.18

Date

2011-03-21 to 2012-03-20
2011-03 to 2012-03

With restrictions – Chiba
Reference

Average effective dose (mSv)

DateInfant (1-year old)Child (10-year old)

Adult

Amano et al. [Amano et al.,
2012]

0.043

0.055

0.017

This assessment

0.044

0.020

0.017

2011-03-15 to 2011-05-14
2011-03 to 2012-05

ATTACHMENT C-15: COMPILATION OF INGESTION DOSE RESULTS

25

VIII. COLLECTIVE DOSES FROM INGESTION OF TERRESTRIAL
FOODS
37.
The Committee has made estimates of the collective dose from ingestion of terrestrial
foods based on the production of food in different regions of Japan. The activity concentrations
were those calculated using the modified FARMLAND model based on the measured
deposition density data for Japan. The collective doses were estimated for the population ofJapan taking account of the proportion of the population who were adults, children and infants.
The collective doses were integrated to 1, 10 and 80 years following the accident and both
effective doses and absorbed doses to the thyroid were considered. The effect of introducing
food restrictions was also considered (see table 29). The per-caput doses ( the collective dose
divided by the number of people in the population) are also presented to provide alternative
estimates for the average dose to the population of Japan from ingestion.
Table 29. Estimated collective doses due to ingestion of terrestrial foods in JapanA stable age distribution was assumed as described in attachment C-12: adult 85.1%, child 9.1%, infant 5.8%
Note: The population of Japan was taken as 128 million people to estimate the per caput doses

Effective dose
Integration period

Collective dose(man Sv)

Thyroid dose

Per caput dose overperiod (mSv)

Collective dose(man Gy)

Per caput dose overperiod (mGy)With food restrictions
1 year

6 500

0.051

49 7000.39

10 years

10 3000.080

53 4000.42

80 years

11 1000.087

54 2000.42

Without food restrictions
1 year

70 4000.55

931 000

7.3

10 years

75 2000.59

936 000

7.3

80 years

76 1000.59

937 000

7.3

38.
These estimated per caput doses are less than the doses presented in tables 1 to 3, where
the first year’s doses were estimated from the measurement database, particularly for
Fukushima Prefecture and the neighbouring prefectures. However, the results are broadly
consistent with the estimated individual doses given in tables 9 to 14 being greater than thedoses estimated for the rest of Japan and less than those for Fukushima Prefecture. Theseestimates of per caput doses based on the total food production in Japan support allowing forfood imports into Japan in the dose estimation.

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27

References
Amano, H., M. Akiyama, B. Chunlei et al. Radiation measurements in the Chiba Metropolitan
Area and radiological aspects of fallout from the Fukushima Dai-ichi Nuclear Power
Plants accident. J Environ Radioact 111: 42-52 (2012).
Aoyama, M., D. Tsumune and Y. Hamajima. Distribution of 137Cs and 134Cs in the North
Pacific Ocean: impacts of the TEPCO Fukushima-Daiichi NPP accident. J Radioanal
Nucl Chem 296(1): 535-539 (2012).
Bailly du Bois, P., P. Laguionie, D. Boust et al. Estimation of marine source-term following
Fukushima Dai-ichi accident. J Environ Radioact 114: 2-9 (2012).
Brown, J. and J.R. Simmonds. FARMLAND a dynamic model for the transfer of radionuclides
through terrestrial foodchains. NRPB-R273. National Radiological Protection Board,
Chilton, 1995.
Kawamura, H., T. Kobayashi, A. Furuno et al. Preliminary numerical experiments on oceanic
dispersion of 131I and 137Cs discharged into the ocean because of the Fukushima Daiichi
nuclear power plant disaster. J Nucl Sci Technol 48(11): 1349-1356 (2011).
MAFF. 2010 Food Self-Sufficiency Table. Ministry of Agriculture, Forest and Fisheries.
[Internet] Available from (http://www.e-stat.go.jp/SG1/estat/List.do?lid=000001089812) on
March 2013. (Japanese).
MIC. The basic information about the population census for 2010 in Japan. Ministry of Internal
Affairs and Communications. [Internet] Available from (http://www.stat.go.jp/data/
kokusei/2010/special/english/index.htm) on 6 December 2011.
Murakami, M. and T. Oki. Estimation of thyroid doses and health risks resulting from theintake of radioactive iodine in foods and drinking water by the citizens of Tokyo after
the Fukushima nuclear accident. Chemosphere 87(11): 1355-1360 (2012).
Nakano, M. and P.P. Povinec. Long-term simulations of the 137Cs dispersion from the
Fukushima accident in the world ocean. J Environ Radioact 111: 109-115 (2012).
Periáñez, R., K.S. Suh and B.I. Min. Local scale marine modelling of Fukushima releases.
Assessment of water and sediment contamination and sensitivity to water circulation
description. Mar Pollut Bull 64(11): 2333-2339 (2012).