REPORT2011 report on radioactivity
monitoring in French
Polynesia
Summary of results from the IRSN monitoring
network
PRP-ENV/SESURE/2013-08

Radiation Protection Division - Environment
Environmental Radioactivity Studies and Monitoring Department (SESURE)

The following persons contributed to this report :
Name

Unit

P. Bouisset
S. Bernagout

Environmental Radioactivity Studies andG. Leclerc

Monitoring Department (SESURE)

J. RuaP. Delabbaye
X. Cagnat

Environmental Sample Processing and Metrology
Department (STEME)

Sampling would not be possible without the contribution of I. Jonhson, G. Taputu,
H. Paeamara, R. Tamarii, T. Temarohirani, T. Flores, the laboratory's island assistants
based in the various archipelagoes of French Polynesia.

Contact:
For more information, please contact :Laboratoire d’étude et de suivi de l’environnement
IRSN/PRP-ENV/SESURE/LESE
BP 18298725 Vairao – Tahiti – Polynésie française
patrick.bouisset@mail.pf

ABSTRACTRadiological monitoring of the French environment is one of IRSN's permanent tasks as part of public
policy on nuclear safety and radiological protection. It helps to guarantee the best possible
protection for the population.
Carried out in Polynesia since 1962, this monitoring focuses on seven islands (Tahiti, Maupiti, Hao,
Rangiroa, Hiva Oa, Mangareva and Tubuai) which are representative of the five archipelagoes. It
consists in taking monthly samples of various kinds from the different environmental compartments(air, water, soil, food, etc.) with which the population may be in contact.
Regarding food, the samples analyzed are representative of the diet of Polynesians living in the fivearchipelagoes of the region and are taken from the marine environment of the open sea, the lagoon
environment and the terrestrial environment.
Almost all samples are measured at the IRSN Laboratory for the Study and Monitoring of theEnvironment, based in Vairao on the island of Tahiti, plus a few samples at the IRSN Orsay
Laboratory.
The year 2011 was marked by the Fukushima nuclear accident, which occurred on March 11. Within
this context, IRSN stepped up its monitoring activities in French Polynesia and was able to confirm
the absence of radiological impact in New Caledonia and Polynesia. As the results of these analyses
were published in the previous annual report (report DEI/SESURE 2011-40), this report does notinclude all the data and results relating to the accident, but provides a summary for the year 2011.
As in recent years, levels of radioactivity, which fell steadily as of 1974 when French atmosphericnuclear weapons testing came to an end, were stable and very low in 2011. The residual
radioactivity is mainly due to 137Cs. In terms of additional dose, this artificial and residual
radioactivity is lower than 5 µSv.yr-1 (5 microsieverts per year). This corresponds to less than 0.5% of
exposure due to natural radioactivity in Polynesia (approximately 1000 µSv.yr-1).

RESUME
La surveillance radiologique de l’environnement français est une mission permanente de l’IRSN dansle cadre des politiques publiques de sûreté nucléaire et de radioprotection, participant à garantir au
mieux la protection des populations.
Exercée depuis 1962 en Polynésie, cette surveillance, qui concerne sept îles (Tahiti, Maupiti, Hao,
Rangiroa, Hiva Oa, Mangareva et Tubuai) représentatives des cinq archipels, consiste à prélever
régulièrement des échantillons de nature variée dans les différents milieux (air, eau, sol, aliments…)
avec lesquels la population peut être en contact.
En ce qui concerne les denrées, les échantillons analysés sont représentatifs de la ration alimentairedes polynésiens vivant dans les cinq archipels de ce territoire, et proviennent du milieu marin depleine mer, du milieu marin lagonaire et du milieu terrestre.
La quasi-totalité des échantillons prélevés sont mesurés au Laboratoire d’Etude et de Suivi del’Environnement de l’IRSN, implanté sur l’île de Tahiti à Vairao, quelques échantillons étant mesurésau laboratoire d’Orsay de l’IRSN.
L’année 2011 a été marquée par l’accident nucléaire de Fukushima, survenu le 11 mars. Dans ce
contexte, l’IRSN a réalisé une surveillance renforcée de la Polynésie française, confirmant ainsil’absence d’impact radiologique en Polynésie et en Calédonie. Les résultats des analyses liés à cettesurveillance renforcée ayant été publiés dans le bilan annuel précédent (rapport DEI/SESURE 201140), le présent rapport ne reprend pas l’ensemble des données et résultats relatifs à cet accident,
mais établit une synthèse pour cette année.
Après une diminution régulière des niveaux de radioactivité depuis l’arrêt, en 1974, des essais
atmosphériques français d’armes nucléaires, l’état radiologique constaté en 2011 est stable, dans lacontinuité des années antérieures récentes, et se situe à un très bas niveau. Cette radioactivité
résiduelle est essentiellement attribuable au césium 137. La dose efficace annuelle liée à laradioactivité d’origine artificielle est inférieure à 5 µSv.an-1 (5 microsieverts par an), soit moins de
0,5 % de la dose associée à l’irradiation naturelle en Polynésie (environ 1 000 µSv.an -1).

CONTENTS
1 INTRODUCTION ................................................................................. 6
1.1 OVERVIEW OF IRSN MISSIONS .....................................................................................6
1.2 LESE, IRSN'S POLYNESIAN BRANCH ...............................................................................8

2 BRIEF DESCRIPTION OF FRENCH POLYNESIA AND ITS POPULATION'S LIFESTYLE .10
3 SELECTED LOCATIONS AND SAMPLES......................................................12
3.1 SELECTED LOCATIONS ............................................................................................ 12
3.2 SELECTED SAMPLES ............................................................................................... 123.2.1 physical environmental SAMPLES ......................................................................... 12
3.2.2 biological environmental SAMPLES ....................................................................... 13

4 RADIOACTIVITY LEVELS AND CHANGES ...................................................14
4.1 PHYSICAL ENVIRONMENT ........................................................................................ 14
4.1.1 Airborne radioactivity ...................................................................................... 14
4.1.2 Radioactivity in water ...................................................................................... 17
4.1.3 Radioactivity in sediments ................................................................................. 17
4.2 BIOLOGICAL ENVIRONMENT ..................................................................................... 18
4.2.1 Marine environment ......................................................................................... 18
4.2.2 Terrestrial environment .................................................................................... 21

5 POPULATION EXPOSURE TO IONIZING RADIATION IN FRENCH POLYNESIA .........24
5.1 GENERAL INFORMATION ......................................................................................... 24
5.2 DOSES RECEIVED BY POPULATION DUE TO ARTIFICIAL RADIOACTIVITY ................................. 25
5.2.1 Effective annual dose due to external exposure ....................................................... 25
5.2.2 Effective annual dose due to inhalation................................................................. 26
5.2.3 Effective annual dose due to ingestion .................................................................. 26

CONCLUSION .....................................................................................28
REFERENCES ......................................................................................30

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1 INTRODUCTION
1.1 OVERVIEW OF IRSN MISSIONSThe French Institute for Radiological Protection and Nuclear Safety was set up under Act 2001-398 of
May 9, 2001. It contributes to public policies concerning nuclear safety and security, and health andenvironmental protection against ionizing radiation, and interacts with all parties concerned by thesepolicies.
In France, nuclear and radiological risk prevention is based on four complementary pillars :Operators are responsible for the safety of
their nuclear facilities. They must demonstrate
the relevance of technical and organizational
resources applied for this purpose (safety files andrelease impact studies).
Public authorities define nuclear safety andradiation protection policies. They organize andimplement inspection activities.
IRSN, a public centre of expert appraisal of
nuclear and radiological risks, assesses reports
submitted by operators for the various competentauthorities. It continuously analyzes plant
operating experience feedback as well as humanand environmental radiation exposure. IRSN expertise is based on its research efforts, which areusually part of an international effort, and ensure it outstanding investigational resources.
Local information committees (CLI) bring together stakeholders concerned by a specific nuclear
facility. They have special access to information and monitor safety, health and environmental
protection issues.
IRSN is a public authority with industrial and commercial activities, placed under the joint authority of:
the Ministry of Ecology, Sustainable Development and Energy (see the Ministry website) ;the Ministry of Industrial Renewal (see the Ministry website) ;the Ministry of Higher Education and Research (see the Ministry website) ;the Ministry of Defense (see the Ministry website) ;the Ministry of Social Affairs and Health (see the Ministry website).
Its budget : €210.8 million of its total budget of €282 million in 2011 was financed by a subsidy from
the Ministry of Ecology under the constitutional bylaw on budget acts (mission: "Research and higher
education", program: "Research on energy and sustainable development and energy", action: "Researchon risks"). This subsidy is supplemented by national, European and international public or private
financing assigned to specific research or expert appraisal programs. IRSN has almost 1,700 employees,
including over one thousand experts and researchers.
Resource allocation :40.2 % for research. The most intensive programs requiring research reactors and considerable
resources (fuel performance, accident simulation, etc.) are shared jointly at international
level ;
50.2 % for technical support for public authorities ;9.6 % for assessments and studies carried out under contract.

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IRSN's activities cover the following fields :nuclear safety: reactors, fuel cycle, waste, medical applications;safe transportation of radioactive and fissile materials;
protection of workers exposed to ionizing radiation: IRSN manages data on the personal
exposure of around 350,000 workers;
protection of the population and the environment against ionizing radiation risks;
protection and control of nuclear materials;
protection of nuclear facilities and radioactive and fissile material shipments against malicious
acts.
IRSN contributes to nuclear transparency :its activities include keeping the public informed. Its Internet portal (www.irsn.fr) provides
readers from many backgrounds with a wide variety of information;
IRSN has signed a framework agreement with the French National Federation of Local
Information Committees, the ANCCLI, to make its expertise accessible to stakeholders and thus
facilitate understanding of often complex technical files;
at the request of the public authorities, IRSN coordinates interdisciplinary expert groups on
potential socially controversial issues.

Figure 1: Map of IRSN sites

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1.2 LESE, IRSN'S POLYNESIAN BRANCHLESE, IRSN's Polynesian branch, moved to Vairao in the summer of 2009 after 44 years in Mahina. It has
carried out continuous radioactivity monitoring in French Polynesia since 1962.
From the outset, this activity has been part of the broader French global radiological monitoring
network (RMFSR) initiative.
An annual report on this monitoring - excluding the experimental sites of Mururoa and Fangataufa - hasbeen submitted to UNSCEAR through the French Ministry of Foreign Affairs since 1966.

IRSN's activities in French Polynesia have a twofold objective :-to monitor levels of artificial radioactivity in all the environmental
compartments where Polynesians live and in the main foodstuffs
they consume;-to help assess doses received by Polynesians.

Monitoring was set up at a time when atmospheric nuclear weapons testing was being carried out by
the major powers (the United States, the Soviet Union, the United Kingdom, France and China). The
tests led to radioactive fallout on a planetary scale over several years. In French Polynesia, IRSN
focused particularly on fallout from the 41 tests carried out by France in this part of the world
between 1966 and 1974, and on its impact on the population.
Today, just as in metropolitan France, LESE continues this work as part of IRSN's continuousradiation protection monitoring activities.
Monitoring focuses on seven islands (Tahiti, Maupiti, Hao, Rangiroa, Hiva Oa, Mangareva and Tubuai),
which are representative of the five archipelagoes. It consists in taking monthly samples of various
kinds from the different environmental compartments (air, water, soil, food, etc.) with which the
population may be in contact.
A reinforced environmental strategy
However, falling levels of artificial radioactivity detected in the environment, together with pressure
from society for improved characterization of pollution, no matter how slight, have led LESE to
gradually shift the focus of its monitoring strategy from human health measurements to increasingly
precise measurements of radioactivity levels still detectable in the environment today.
Since 2009, LESE has therefore been working to develop an observatory of pollutants in Polynesianlagoons, in partnership with IFREMER and CRIOBE (CNRS). The aim of this project, funded by the
Secretary of State for the French Overseas Departments and Territories from 2009 to 2011, then by thejoint State-Country project contract from 2012 to 2014, is to monitor contamination of a biologicalindicator (nacre) by metals, radioactive substances, hydrocarbons, and organochloride compounds.
The project was selected as one of the top priorities of GOPS, the South Pacific Integrated Observatory
for the Environment and Terrestrial and Marine Biodiversity, of which IRSN has been a part further toan agreement signed in Paris on March 9, 2010. The project was also among the priorities for the 20102013 action plan defined as part of the Grenelle de la mer marine environment round table in French
Polynesia.

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Supporting the public authorities in emergencies
LESE also carries out specific assessments, such as conducting analyses on the quality of theenvironment around sites, or radiological inspections, for the public authorities and private
enterprises.
Given the small number of nuclear facilities in the southern hemisphere, and their distance from
France, a radiological emergency is highly unlikely. However, even if an accident were to occur in thenorthern hemisphere, monitoring would be required because of trade and fish migration.
In 2011, reinforced monitoring had to be set up in French Polynesia and New Caledonia [3] in the wakeof the Fukushima nuclear accident in Japan. This operation confirmed that the accident had had noradiological impact in these regions. Pelagic fish are still being monitored as they could carryradioactive traces when they migrate southwards from the North Pacific.
Chapter 2 of this 2011 report includes a brief description of French Polynesia in terms of geography,
climate and habitat, together with an overview of the main dietary habits of the region's three mainareas: Tahiti, the other high islands, and the low islands or atolls.
Chapter 3 describes the seven sampling zones in the different archipelagoes (two islands each for theSociety Islands and the Tuamotu Islands, one of the Gambier Islands, one of the Austral Islands, and oneof the Marquesas Islands).
The three main types of samples are also presented, namely samples from the physical, marine andterrestrial environments. Almost all samples of the last two types enter into the Polynesian population's
diet.
Levels of radioactivity are given in Chapter 4. The first results for 2012 in the oceanic marine
environment reveal no traces of radioactivity in French Polynesian territorial waters that can be
attributed to the Fukushima nuclear accident.
Chapter 5 discusses the dosimetric significance of these radioactivity levels.
Chapter 6 summarizes the main results for 2011.
Another document relating to this report (Report PRP-ENV/SESURE 2012-18) can be consulted on the
IRSN website to find out more about radioactivity and radiation protection, together with theradioactivity monitoring results in French Polynesia for 2011. It includes:
activity levels in the physical environment;
activity levels in the biological environment;dose calculation results.

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2 BRIEF DESCRIPTION OF FRENCH POLYNESIA AND ITSPOPULATION'S LIFESTYLE
French Polynesia is made up of 118 islands, 76 of which are inhabited, divided into five archipelagoes:
the Society, Tuamotu, Gambier, Austral and Marquesas Islands. The islands are scattered over an areaof five million square kilometers in the South Pacific (see Figure 2), with a total emerged land area ofaround 3,500 sq km. The islands are not heavily populated; according to the August 2007 census, there
are fewer than 260,000 inhabitants. Most of the population (70%) lives on the island of Tahiti.
Polynesia has a wet tropical climate with no extremes. Average annual temperatures are moderate (21to 28°C) and there is little temperature difference between seasons. Average rainfall is high, although
not excessive: 1,800 to 2,000 mm per year. The islands are very sunny, with 250 sunshine hours permonth on the west coast of Tahiti. The lagoons are warm, with water temperatures between 23 and27°C all year round. These conditions are conducive to an outdoor lifestyle. In view of the long
distances, small populations and differences in lifestyle, seven islands of volcanic origin andrepresentative of the five archipelagoes were selected as sampling areas.


Tahiti and Maupiti, high islands in theSociety Islands;

Mangareva, a high island in the GambierIslands;Tubuai, a high island in the Austral
Islands;

Hiva Oa, a high island in the Marquesas
Islands.

The high islands (e.g. Hiva Oa shown opposite) aremade up of mountains that can be more than
2,000 m high and deep, narrow valleys, so most of
the population is concentrated along the coasts.
Market gardening, fruit growing and somelivestock farming are carried out there.
People in Tahiti have a varied diet and can find an abundance of produce from all over Polynesia. There
are two markets in Papeete and its suburbs, which alone provide some 40,000 people with local
produce such as fish and shellfish, vegetables, fruit, and pork, both from Tahiti and the other islands.
Many well-stocked food stores can also be found there selling local and imported foods. The other highislands have access to a wide range of local produce including fruit, vegetables, and fish, as well as
imported essentials such as rice, flour, oil and sugar, which are shipped in regularly.


Hao and Rangiroa (photo opposite), two
inhabited atolls in the Tuamotu Islands.

These low islands or atolls are simply ring-shaped
coral reefs, almost level with the sea, and for themost part are planted with coconut trees.
Their population lives mostly on locally caught fish,coconuts and some chicken and pigs from family
livestock farms. Imported produce is not so varied
and is shipped in less regularly.

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Figure 2 : Map of French Polynesia showing the various archipelagoes and sampling points

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3 SELECTED LOCATIONS AND SAMPLES
3.1 SELECTED LOCATIONSThe seven islands selected had to meet certain essential criteria, namely :ensure geographical coverage of all of French Polynesia, i.e. nearly 3,000 km from east to west
and 2,000 km from north to south, and a total area of more than 5,000,000 sq km ;take into account the two types of islands: high islands and atolls ;allow for the highly irregular population distribution ;take into account the location of the Mururoa and Fangataufa atolls, where French nuclear
weapons testing was carried out between 1966 and 1974, and the prevailing easterly tradewinds, which have a major impact on the trajectories of fallout from these tests ;select the most populated islands of each archipelago; Maupiti was selected in addition to
Tahiti in the Society Islands because it is the westernmost island, and Hao was selected inaddition to Rangiroa in the Tuamotu Islands to allow for the very wide area covered by thisarchipelago and because it is nearer to the former nuclear test sites.

3.2 SELECTED SAMPLES
Samples are selected on the basis of two monitoring objectives in French Polynesia :to monitor levels of artificial radioactivity in the environment ;to estimate population exposure to this artificial radioactivity.
Six permanent assistants work with the laboratory to collect and send samples. Samples from Tahiti aregathered by laboratory staff.
In 2011, a total of 177 samples were taken; 24 from the physical environment and 153 from thebiological environment.
In view of falling environmental radioactivity levels, analyzing the same samples taken from the sameisland several times a year is no longer justified. For this reason, the number of lagoon fish samples
was reduced compared to previous years in favor of analyses on nacre from Pinctada margaritifera.
These analyses are to be used in a planned network for monitoring pollutants, radioactive substances,heavy metals, and organochloride compounds [1]. The network is currently being implemented incollaboration with IFREMER and CRIOBE (CNRS) teams. In 2011, five gamma spectrometry analyses,
supplemented by chemical pollutant analyses, were carried out at two stations, one in Vairao and theother in Papeete port.

3.2.1 PHYSICAL ENVIRONMENTAL SAMPLES
Physical samples included air samples obtained byfiltering, sea, rain (photo opposite), river andspring water samples taken in Tahiti, andsediment samples from the various islands.
Rainwater analyses were performed monthly until
2009, then on a half-yearly basis as of 2010.
Sampling was carried on uninterruptedly but thecollection surface area was reduced.

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3.2.2 BIOLOGICAL ENVIRONMENTAL SAMPLES
The number of biological samples taken in 2011 per island was as follows : 67 for Tahiti, 17 for Maupiti,
14 for Tubuai, 8 for Rangiroa, 19 for Hiva Oa, 13 for Mangareva and 7 for Hao. A further eight samples
were taken of imported produce consumed throughout the archipelagoes.
Of the 153 samples taken in 2011, 23 concerned three categories of the marine environment, namely
pelagic fish, lagoon fish and other marine samples (shellfish, etc.) and 130 were terrestrial samples(photos below).
Pelagic fish samples
Three samples of pelagic (or open sea) fish (yellowfin tuna).
Lagoon fish samples
Seven samples of fish living in the lagoon or in its immediate vicinity close to the reef,
exclusively loaches and groupers. Several different species were analyzed until 2010, including
snappers, emperors and trigger fish. Loaches and groupers were taken as bioindicators of 137Csconcentrations in lagoon water as they are the most likely to concentrate cesium in their flesh[2].
Other marine samples
Thirteen samples of mollusks and shellfish: 6 giant clams (tridacna), 5 nacres and 2 octopuses.
Terrestrial samples
One hundred and thirty samples broken down as follows: 31 drinks (4 drinking waters,
8 coconut waters, 1 beer, 1 fruit juice, 1 soda and 16 milk samples), 35 vegetables (11 leaf
vegetables, 14 fruit vegetables, and 10 root vegetables), 32 fruits, 4 meats and eggs,
11 pasture grasses and 8 additional samples concerning imported produce (1 beer, 1 milk,
3 meats and 3 other products : bread, rice, and potato).

Grapefruit tree

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4 RADIOACTIVITY LEVELS AND CHANGESAll radioactivity measurements in Polynesia were performed by LESE, except for the gamma spectral
analyses performed by the IRSN Environmental Radioactivity Measurement Laboratory (LMRE) in Orsay,
France (Essonne - 91).
To perform these measurements, LESE has various equipment for direct measurement via gamma
spectrometry or after selective radiochemistry for Pu and 90Sr analyses.

Gamma spectrometry
Proportional counting (90Sr)

4.1 PHYSICAL ENVIRONMENT
4.1.1 AIRBORNE RADIOACTIVITY
Continuous aerosol sampling was performed byfiltering on a high-flow aerosol collector
station (approximately 300 m3/h).
Table 1 below lists the annual mean activity
levels obtained over the past three years for137
Cs, 7Be, 22Na, 40K and 210Pb. The indicateduncertainties are due to the measurement
techniques and not natural variations. These
results are compared with the levels obtainedin Orsay, near Paris.
The monthly mean activity levels, along withthe sampled air volume for each period for the
Tahiti and Orsay stations, are shown in
Tables AI 1 and AI 2 of the Appendix report,
which can be found on the IRSN website(report PRP-ENV/SESURE 2012-18).

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Table 1 : Annual mean activity levels (µBq.m-3) from 2009 to 2011 for the 5 radionuclides detected in thecontinuous aerosol samples obtained in Tahiti and Orsay. These activity levels are calculated based on theweighted monthly mean activity levels for the sampled air volumes.

TahitiRadionuclide
137

Cs
Be
22
Na
40
K
210
Pb
7

2009
0.08 0.04
3970 1180
0.46 0.20
8.1 3.1
121 362010
0.08 0.04
2990 930
0.26 0.11
8.0 2.6
78 25

Orsay
2011
0.10 0.06
3260 950
0.29 0.12
8.3 2.7
86 26

2009

2010

0.15 0.073680 1060
0.46 0.18
6.2 2.2
380 1100.15 0.06
3550 990
0.44 0.17
5.4 2.1
350 100

2011
3.9
3900
0.33
7.0
550

1.6
760
0.14
3.2
120

The only artificial radionuclide that is still detected in French Polynesia is 137Cs. This indicates thepersistence of fallout from atmospheric nuclear weapons testing. No changes were detected in theatmospheric concentration of this radionuclide over the 2009-2011 period. However, two values slightly
above "normal" were recorded from August 1 to 10 (0.43 0.15 µBq.m-3) and August 10 to 20 (0.14
0.06 µBq.m-3). If the increased concentration of 137Cs was linked to the accident in Fukushima, otherradionuclides that "accompany" 137Cs and which are characteristic of the accident would also have been
detected; but no other artificial radionuclide, and in particular 134Cs, were detected. This increased
concentration is therefore not linked to the Fukushima accident. The resuspension of dust carrying old
137
Cs deposits (from the Taravao plateau, for example) may explain this observation.
In metropolitan France, a sharp increase was noted in the concentration of airborne 137Cs following theaccident at the Fukushima nuclear power plant, which affected the entire northern hemisphere. Other
radionuclides that are characteristic of this accident were also detected ( 131I, 132I, 134Cs, 136Cs, 121Te,
129m
Te and 132Te) [3].
The four natural radionuclides come from the upper atmosphere ( 7Be, 22Na) and lower atmosphere (40K,
210
Pb).
The following figures show variations in 137Cs activity levels in aerosol samples taken in Tahiti (Figure 3)
and in Essonne, France (Figure 4) over the past 40 years. The effects of the Chernobyl and Fukushima
accidents on activity levels in France can be noted. Overall, the concentrations have decreased by afactor of 1000 over the past four decades, with activity levels in France remaining approximately fivetimes higher than in Polynesia.

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Figure 3 : 137Cs activity levels (µBq.m-3) in aerosol samples taken in Tahiti from Jan 1971 to Dec 2011

Figure 4 : 137Cs activity levels (µBq.m-3) in aerosol samples taken in Orsay (Essonne) from Jan 1971 to Dec 2011

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4.1.2 RADIOACTIVITY IN WATER
A 360-liter seawater sample was taken in 2011 south of Tahiti (at Vairao) in the lagoon at a depth of
1.5 meters. The value of 1.05 0.05 mBq.L-1 measured for 137Cs (Table AI-3 of the Appendix available
on the IRSN web site – PRP-ENV/SESURE 2012-18) is compliant with the values generally obtained in thisregion of the Pacific Ocean, and with the values obtained in previous years north of Tahiti (at Point
Venus – Mahina sampling station).
This year, commercial spring water from Tahiti, which is widely consumed on all the archipelagoes, wasanalyzed. The artificial radionuclide 137Cs was not detected in this sample, nor in the freshwater
samples (rainwater and spring water collected in Tahiti and drinking water collected in Tubuai, Hiva Oa
and Maupiti). All these results are below detection limits (DL) (Table AI-3). River water collected on thepeninsula was analyzed in 2011. An extremely low 137Cs concentration (0.10
0.02 mBq.L-1) was
detected in the sample. These results were the same as those obtained in 2009 and 2010 from samplingat the same location. This value is close to the detection limit, and is nearly the same as themeasurements taken in previous years north of Tahiti (Papenoo).
Only naturally-occurring 40K is systematically detected in these samples.

4.1.3 RADIOACTIVITY IN SEDIMENTS
Sediments are not systematically sampled each year. From 2009 to 2011, a sediment sampling campaign
was conducted at various points on the seven islands in the radioactivity monitoring network, and also
on one of the other Tuamotu islands (Apataki).
The gamma spectrometry results cover 19 marine sediment samples taken in the lagoons of Tahiti,
Maupiti, Tubuai, Hao, Mangareva (Gambiers), Rangiroa and Apataki, and also ocean sediments from Hiva
Oa and Rangiroa. For artificial radionuclides (Table AI-4 for 2011 results and reference [5] for the otherresults), only 137Cs was detected at low activity levels (< 0.25 Bq.kg -1 for dry sample) in four locations :Tahiti (the port of Papeete and the black sands of Vairao), Tubuai and Gamblers . The other 15 results
are expressed at the detection limit (pink dots on figure 5).

Gravelines

Brest (29)Pornichet(44)

Figure 5 : Activity levels for 137Cs in marine sediments from French Polynesia (Rangiroa, Tahiti, Hao, Gambiers,
Hiva Oa, Maupiti, Tubuai and Apataki) and in France (Pornichet, St Pierre d’Oléron, Brest, Jobourg,
Herqueville, Cherbourg and Gravelines).

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Figure 5 shows a comparison of the results obtained in French Polynesia with the results from marine
sediments taken from beaches of the Atlantic and the English Channel in France in 2009 [4]. The
concentration levels in Polynesia are 10 to 20 times lower than those found in France, which wasaffected by the Chernobyl accident and greater atmospheric fallout from nuclear tests in the northernhemisphere.

4.2 BIOLOGICAL ENVIRONMENT
The analyses of biological samples, primarily foodstuffs, covered the edible parts. The 153 samples
were measured by gamma spectrometry, including 19 that were subject to radiochemistry followed byalpha spectrometry to determine the plutonium isotope doses. The 90Sr measurements for these19 samples could not be completed due to difficulties procuring the gas (Ar-CH4) required to operate
the counters. These results will be included in the 2012 report.
Only a few traces of 137Cs and plutonium were measured in these samples. The samples analyzed in2011 contained no traces of 60Co, which has only been detected in a few samples of giant clams(tridacna) in recent years.

4.2.1 MARINE ENVIRONMENT
4.2.1.1 Pelagic fish

In 2011, three samples of yellowfin tuna(Thunnusalbacares, see picture opposite) fromcoastal fisheries in Mangareva, Hao and Rangiroa
were analyzed by gamma spectrometry. Tables AII1 to AII-7 in the Appendix report available on the
IRSN website (report PRP-ENV/SESURE 2012-18) list
detailed results for each island.

The 137Cs values are the same as the values observed in recent years, and the residual levels remain
fairly uniform, 0.1 to 0.2 Bq.kg-1 for a wet sample. The maximum level (0.20 Bq.kg-1 on wet sample)
was detected in the sample from Hao.
For the other gamma-emitting artificial radionuclides, such as 60Co, alpha emitters, 238Pu and 239+240Pu(three samples analyzed), the results are below the detection limits.

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FOCUS
Monitoring the impact of Fukushima on the marine environment in French Polynesia
In response to the accident at Fukushima-Dai-ichi, special monitoring was implemented by IRSN-LESE in
French Polynesia and New Caledonia [3, 5]. The purpose of the monitoring was to detect any
atmospheric contamination between March and July 2011.
Beginning in September 2011, special attention was given to pelagic fish that may have conveyed
contamination from the North to the South Pacific. Fish samples were taken at an increased frequency,
and seawater sampling is performed on a monthly basis.
The monitoring is focused on the primary radionuclides that were released to the environment during
the accident in Japan in March 2011: cesium-134 and cesium-137.
The cesium-137 isotope has a radioactive half-life of 30 years, and has remained in the environment
since atmospheric nuclear tests (1.3 x 1018 Bq released into the environment between 1945 and 1980).
Other sources of cesium-137 include fallout from the Chernobyl accident (less than 10 17 Bq, foundmainly in Europe) and releases from fuel reprocessing plants and nuclear power plants (1.3 x 108 Bq in
1999 for a 1300 MWe reactor). The impact of the Fukushima accident is characterized by the detectionof cesium-134 (radioactive half-life of 2.1 years) and an increased concentration of 137Cs.
Seawater
In French Polynesia, the concentration of 137Cs is measured once a year by LESE in a single sample,
taken at the Pointe Venus sampling station north of Tahiti until 2008, and taken at Vairao south of
Tahiti since 2009. Since January 2012, the sampling has been performed once a month. To account for
the low concentrations of 137Cs in seawater, several hundred liters of seawater were sampled.

1,8
1,6

Accident de Fukushima

Activité de 137Cs en mBq.L-1

2

1,4
1,2
1
0,8
0,6
0,4
0,2
0

déc- juin- déc- juin- déc- juin- déc- juin- déc- juin- déc- juin06
07
07
08
08
09
09
10
10
11
11
12

Concentration of 137Cs in seawater from Tahiti

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Pelagic fish
Pelagic fish samples are provided by the local fishing industry, a long-standing partner of LESE. The fish
are provided from all five archipelagoes of French Polynesia. These are non-industrial fish caught for
local consumption in the vicinity of the islands in question. The species of fish is variable (tuna, bonito,
swordfish, Mahi-mahi, etc.). In addition, as part of the "Pakaihi i te moana" oceanography campaign, 6
samples were taken from the waters off the Marquesas Islands in February 2012.
The only artificial radionuclide detected in fish in 2010, prior to the Fukushima accident, was 137Cs atvery low levels (between 0.34 and 1.32 Bq.kg -1 for a dry sample, the latter figure being the equivalentof 0.44 Bq.kg-1 for a wet sample). The maximum permitted levels for cesiums in foodstuffs is 500 Bq.kg-1(Commission Implementing Regulation (EU) no. 351/2011 of 11 April 2011). The admissible level was
reduced to 100 Bq.kg-1 (Commission Implementing Regulation (EU) no. 284/2012 of 29 March 2012) in
response to the regulations recently implemented by the Japanese authorities.
The samples taken in Polynesian waters following the Fukushima accident, from September 2011 to May
2012, show no traces of 134Cs. The detection limits (DL) are between 0.16 and 0.68 Bq.kg-1 for a dry
sample. The activity levels for 137Cs are consistent with the results obtained in previous years, between
0.34 and 0.85 Bq.kg-1, on a dry sample.
Recent data obtained concerning fish caught off the coast of California [6] indicate that the releases
from the Fukushima accident had an impact on the flesh of bluefin tuna (Thunnus orientalis) in 2011,
with a mean 134Cs value of 4.0 1.4 (SD), and 6.3 1.5 (SD) Bq.kg-1 of 137Cs on a dry sample, whereas
the measurements in 2008 indicated ‘0’ and 1.4 0.2 respectively for 134Cs and 137Cs. However, analysesof yellowfin tuna (Thunnus albacares) do not show any contamination in 2011. The passage of certain
species through contaminated waters and their rapid migration explain these observations.

Concentration of 137Cs in pelagic fish, for all species, sampled off Polynesian coast

Other samples are scheduled for 2012 in order to confirm these observations. It is probable that, if
some of the species that were initially contaminated in Japanese coastal waters or in the Kuroshio
ocean current had been caught in the South Pacific, the concentrations would have been difficult to
detect. The competition between the duration of the migration period and the biological half-life ofcesium in the muscles of the fish may significantly reduce the possibility of measuring any signs ofcontamination for species caught in the South Pacific.

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4.2.1.2 Fish and other marine products in the lagoon environment

Twenty samples were taken in 2011, 7 fish(groupers and loaches only) and 13 other products(giant clam, octopus and nacre). All were
measured by gamma spectrometry. The seven fishand six giant clams underwent plutonium analysis.
Tables AII-1 to AII-7 in the Appendix reportavailable on the IRSN website (report PRPENV/SESURE 2012-18) provide detailed results ofactivity levels.

Radioactivity levels remain low for all the samples and all the locations.


It is still possible to quantify 137Cs in all the fish from the analyzed lagoons, but rarely in theother lagoon samples. The higher concentration levels found in fish than in other marineorganisms, in particular mollusks, can be explained by the fact that fish is higher up the foodchain and by the active retention of 137Cs, a chemical equivalent of potassium, in fish muscle.
Values are always higher in the flesh of groupers or loaches than in other fish, which is why it
has been decided that samples will only be taken from these fish. The highest values wereobserved in groupers at Hao (0.33 Bq.kg-1 wet) and Tubuai (0.22 Bq.kg-1 wet).

In recent years, 60Co has only rarely been quantified in the analyzed samples. The only
quantifications possible were for giant clams, which contain concentrations of radionuclides
due to the fact that they filter seawater. In 2011, all the results were below the detection limitof 0.04 Bq.kg-1 wet.

It was possible to quantify 238Pu in five of the six giant clams analyzed, and 239+240Pu in all six
giant clams. These radionuclides were not detected a single time in the flesh of the lagoon fish
analyzed in 2011.

4.2.2 TERRESTRIAL ENVIRONMENT
4.2.2.1 Cow’s milk
In response to the accident in Fukushima, weekly analyses were performed from March 16 to May 11,2011, and then monthly through the end of the year, on milk samples taken from the Taravao plateau
in Tahiti. Levels of 137Cs remained consistent with those measured prior to the accident, and no traceof 134Cs, 60Co or 131I was detected in these samples. The activity levels for 137Cs were comparable to thevalues observed in New Zealand in 2010 [7].
A sample of UHT (or "long-life" milk) from France was measured, providing a detection limit of
0.2 Bq.L-1. Table AII-7 in the Appendix report available on the IRSN website (report PRP-ENV/SESURE
2012-18) lists the detailed results.

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Figure 6 : 137Cs activity levels since 1970 for cow's milk from the Taravao plateau

A very slow decrease in radioactivity can be observed since the 1990s (blue slope). This decrease ismuch slower than that observed following the atmospheric nuclear tests in the 1970s (pink slope). As inprevious years, the concentration of 137Cs in locally produced milk was slightly higher in 2011 than in
the imported UHT milk (0.05 Bq.L-1 measured in a 2010 sample from France). This observation is linked
to soil-plant transfer factors, which are approximately 100 times greater than those normally measured
in Europe [8]).

4.2.2.2 Other terrestrial samples
In 2011, 95 samples were taken from foodstuffs
produced locally and regionally on the fivearchipelagoes:
15 drinks (not including milk),
35 vegetables,
32 fruits,
4 meats,
11 grass samples,
7 samples of imported products (notincluding milk).


The results of gamma spectrometry analyses, (alpha for Pu) are shown in the tables inAppendix III. Beginning in 2011, only the copra samples underwent analysis for plutonium. Morethan half the analyses still have quantifiable traces of 137Cs, and six measurements showedvalues above 1 Bq.kg-1 wet (2 in 2009 and 2010, 6 in 2008 and 10 in 2007). Phenomena causing
dilution of this radionuclide in the environment make it increasingly difficult to measure, as its
durability is several hundred years due to its radioactive half-life.



60



In the 6 measured copra samples, 238Pu has never been detected, and there was only one resultfor 239+240Pu, close to the detection limit, at a value of 0.06 0.03 mBq.kg-1 wet.

Co was never quantified in these terrestrial samples.

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General comment concerning measured concentrations of radionuclides in foodstuffs
For informational purposes, the maximum permitted levels of radioactive contamination are indicatedfor foodstuffs and feed for livestock. These levels are set by regulation No. 3954/87 (Euratom), andwere modified following the Fukushima accident (Commission Implementing Regulation (EU) no.
284/2012 of March 29, 2012). In Table 2 below, the levels are compared with the maximum values
found in food produce consumed in French Polynesia.
Table 2 : Maximum permitted levels (MPL) of radioactive contamination for foodstuffs (left-hand column)
compared with maximum concentration levels measured in 2011 for foodstuffs in Tahiti (right-handcolumn)MPL in Bq.kg-1 (LH column)/maximum concentrations measured in foodstuffs(RH column) in French Polynesia in Bq.kg-1
Radionuclide
137

Milk, baby food

Other foodstuffs

Liquids

Cs or 60Co

50

0.4±0.041

100

52

10

0.032±0.0143

Plutonium andalpha emitters

1

nm4

80

1.7±0.25

20nm

It should be noted that the maximum values measured in the foodstuff samples are well below the
maximum permissible levels

1

Measured value on milk sample from Tahiti
Measured value on copra sample from Tubuai
3
Measured value on pineapple juice sample from Tahiti
4
nm: Pu was not detected in any milk sample or other drink
5
Measured value in a giant clam sample from Tubuai
2

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5 POPULATION EXPOSURE TO IONIZING RADIATION IN FRENCHPOLYNESIA
5.1 GENERAL INFORMATIONAll sources of natural and artificial radioactivity contribute to exposure levels. Exposure to naturalradioactivity may come from several different sources. In Polynesia, naturally-occurring radioactivity
is primarily due to:Cosmic radiation, resulting in external exposure that varies depending on altitude, ofapproximately 0.3 mSv/year at sea level ;Exposure through ingestion of natural radionuclides in food and water, of approximately
0.25 mSv/year (approximately 0.18 mSv/year due to potassium-40 alone) ;The presence of natural radionuclides in soils, a cause of terrestrial radiation and external
exposure (239U, 235U, 232Th, 40K, etc.): this radiation varies a great deal with the type of soil, andis relatively low in French Polynesia (less than 0.05 mSv), whereas it may reach levels as high as
several mSv/year in some parts of the globe (8 to 17 mSv/year in Brazil, for example) ;Radon, a noble radioactive gas produced by the disintegration of uranium in the Earth's crust, iswidely abundant in air and can accumulate in enclosed, poorly ventilated spaces. Very little
radon is detected in Polynesia due to the soil types (non-granitic with low uranium content) andthe local lifestyle: the houses are very open and well-ventilated, meaning that there are only
negligible quantities of radon accumulation. The radon dose for French Polynesia is relatively
low, and is estimated at 1 mSv/year.
It is estimated that natural radioactivity in French Polynesia results in a cumulative exposure of 1 to
2 mSv/year. A comparison should be made between exposure to natural radiation and exposure to
artificial radioactivity. Considering the specific nature of nuclear activities in French Polynesia (noindustrial nuclear facilities, nuclear weapons testing from 1966 to 1974), artificial radioactivity
mainly results from the following factors :Residue from atmospheric fallout due to nuclear weapons testing, a source of 137Cs, 90Sr, 3H, 14C
and uranium and plutonium isotopes :othe percentage of these radionuclides found in the air as aerosols is now negligible. The
majority are found in soil deposits or in the substrate, and contribute to externalradiation ;oThey are then incorporated in the region's fish and locally produced foodstuffs(primarily copra, lagoon fish, coconut water, milk and beef) and become a source ofcontamination through ingestion.

Radionuclides in local foodstuffs and drinks that have been imported. In which case, it ispossible to find, in addition to the radionuclides present in French Polynesia, other isotopes
produced by nuclear activities outside of Polynesia ;Medical examinations and treatments: in industrialized countries, a person receives an averageof 1.6 mSv per year, and the worldwide average is approximately 0.6 mSv.year-1.
The purpose of the following chapters is to estimate the doses received by local populations from
artificial radioactivity via ingestion of local and imported foodstuffs, from external exposure toradionuclides present in the air and ground, and from the inhalation of radionuclides in the air.

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5.2 DOSES RECEIVED BY POPULATION DUE TO ARTIFICIALRADIOACTIVITY
The effects on individuals exposed to radionuclides are not measured directly. They are quantified using
the effective dose for the entire body. The standard measurement unit for this dose is the sievert (Sv),or more often its sub-units: the millisievert (1 mSv = 0.001 Sv) and the microsievert (1 µSv = 0.000001
Sv). With some radionuclides, the dose can also be calculated for a specific organ when the organ ismore sensitive to the effects of radiation than the whole body (such as iodine for example, for which
the target organ is the thyroid gland).
A distinction is made between external and internal exposure, depending on how the radiation comes
into contact with the organism. External exposure is when an individual is exposed to sources ofradiation that remain outside the body (for example, exposure to radionuclides in the air or in soil
deposits); the received dose depends on exposure time.
In the case of internal exposure, the radionuclide enters the organism - normally through ingestion or
inhalation. The resulting internal radiation then continues beyond the moment when the radionuclide
enters the body, and will decrease based on the radioactive half-life of the incorporated radionuclide
and the rate at which it is eliminated.
For an internal contamination by a radionuclide with a long half-life, the confirmed dose is calculated.
This dose indicates, at the moment the contamination occurs, all the different "future" doses theindividual will be exposed to over the entire time period required to completely eliminate theradionuclide. In cases where the radionuclide will remain in the body, the calculated period will thenbe the lifetime of the individual, ranging from 50 years for an adult to 70 years for a child 0-1 years old.
The annual effective doses due to residual artificial radioactivity that are calculated in this reportcomprise three elements :external exposure, due mainly to activity in the soil ;inhalation, due to radioactivity carried by aerosols ;ingestion, from food and drink.
By convention, the detection limit (DL) values are included in the calculations if the measured values
are below the DL. It should be noted that this simplified calculation method is not precise, and may
result in biases when estimating the received dose. The methodology for calculating doses is to bereviewed in the near future.
The dose coefficients per inhaled activity unit and per ingested activity unit are those recommended by
the ICRP 71 [9] and ICRP 67 [10].
The tables in Appendix III show all the raw results. The doses are indicated for each sampling site andfor two populations: adults and children under the age of five.

5.2.1 EFFECTIVE ANNUAL DOSE DUE TO EXTERNAL EXPOSURE
External ambient exposure in French Polynesia comes primarily from natural sources. A small amountof artificial sources also exist due to fallout from former nuclear weapons testing in the atmosphere.
The additional effective dose from artificial sources due to external exposure, estimated based on
137
Cs deposits (the only artificial radionuclide still detectable in the soil), does not exceed a fewµSv/year. The external dose values are for 137Cs activity levels in soil samples taken in 2000 in Faa’a
for the island of Tahiti, and in 2005-2006 for the other islands [11].

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5.2.2 EFFECTIVE ANNUAL DOSE DUE TO INHALATION
The additional effective artificial dose due to inhalation, calculated based on the concentration of137
Cs measured in the air in Tahiti, is less than 10 -5 µSv/year, both for adults and children under theage of five. It is considered negligible in comparison with the other two components (ingestion andexternal exposure).

5.2.3 EFFECTIVE ANNUAL DOSE DUE TO INGESTION
The additional effective artificial dose due to ingestion is calculated based on food intake (1982 survey[12] updated in 1991), which makes a distinction between products that are only produced locally,
regional products from Polynesia, and imported products.
All imported produce, except for yogurt and pasta, were measured in 2011. Local yogurt production
has grown significantly, and the imported product is now rare and expensive. It can no longer bejustified as an imported product in the food intake. The analysis is performed every five years for
pasta, the same as for local products when the quantity in the food intake is less than 5 kg [2].
When the sample is not taken, the dose is calculated using the sampling results from the previous year
(or from previous years) on the same island, or, if this is not possible, with the results obtained for thesame matrix on another island.
For radioactivity levels as low as those observed in French Polynesia, the sampling variability is themain source of the temporal and geographic differences found in the calculated doses in recent years.
In order to limit this effect, high quantities are sampled (several kilograms). In addition, theradioactivity analyses for these samples have been improved (longer measurement periods, more
effective detector) in order to reduce the detection limits.
Figure 7 shows that the dose contributions for adults (the same trends can be observed for children)from local and imported produce have decreased from 2008 to 2009 compared with the two previous
years. However, these findings do not indicate any changes in radioactivity in the environment. They
mainly indicate variations in concentration levels measured in certain foodstuffs. They also result from
improved analysis protocols which have made it possible to obtain lower detection limits since 2009. In
particular, a longer counting period was introduced for the most consumed products when performing
gamma spectrometry measurements (137Cs and 60Co) to reduce detection limits to a minimum (it ranges
from 24 to 72 hours, depending on the samples).

Figure 7 : Additional ingested doses from 2006 to 2011 for adults due to consumption of local and imported
products on the various islands.

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Values increased significantly in 2010 [5], mainly for the islands (all except Hao and Rangiroa) where
beef from Tahiti is included in the food intake.
In 2011, the concentration of 137Cs in beef was 3 Bq.kg-1 wet (8.8 in 2010 and 0.9 in 2009), which meansa lower dose in 2011 compared with 2010. This decrease was compensated for by the increased doses
measured in imported rice and UHT milk, and also an increase in the local beer due to worse 137Cs and60
Co detection limits that year.
In addition, slightly higher 137Cs values in a single product, such as lettuce in Hiva Oa or fish from the
Hao lagoon, also increase the annual dose for consumers on these islands.
And finally, the difference in dose contributions between local and imported foodstuffs are, in general,
not only due to different concentrations of radioactivity, but also to the respective portions they
represent in food intake. For example, fish consumption is up to eight times higher on the atolls than on
the upper islands. As a result, the calculated dose may be up to eight times higher on these atolls forthe same concentration level measurements.
In 2011, the estimated doses due to the consumption of Polynesian products was between 0.5 and1.8 µSv.year-1 (Maupiti and Tubuai) for adults, and between 0.29 and 0.9 µSv.year -1 for children on thesame islands.
In 2011, as in previous years, the same foodstuffs were the primary contributors to the dose for adults :beef from Tahiti (0.04 µSv.year-1), also
consumed in even larger quantities on Maupiti(0.13 µSv.year-1), Mangareva (0.24 µSv.year-1)
and Tubuai (0.29 µSv.year-1) ;pork from Tahiti (0.11 µSv.year-1 in 2011,0.38 µSv.year-1 in 2010) ;copra from Rangiroa (0.75 µSv.year-1) andTubuai (0.24 µSv.year-1) ;Drying copra in Tuamotu

fish from the Hao lagoon (0.72 µSv.year-1)
and Rangiroa (0.41 µSv.year-1), due to the factthat consumption of this product (85.5 kg peryear) is 4 to 10 times higher than on the otherislands ;lettuce from Hiva Oa (0.37 µSv.year-1). In 2010, it was cabbage that had the highest value(0.11 µSv.year-1) ;And finally, in 2011, higher values were recorded for papaya from Mangareva (0.2 µSv.year-1).
Over the past six years, no foodstuff has contributed an additional artificial dose greater than
1 µSv.year-1. In 2006, values greater than 1 µSv.year-1 were still measured for two samples(1.3 µSv.year-1 for pineapple consumption by adults in Tahiti and 1.2 µSv.year -1 for copra consumption
in Rangiroa).
To put these values into perspective, they should be compared with the dose of natural radioactivity
presented in Chapter 5.1. This dose is approximately 1 to 2 mSv.year -1 if all sources are taken into
account (radon, radiation of cosmic or terrestrial origin, natural radionuclides such as 40K, etc.).

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CONCLUSION
In 2011, IRSN once again performed radiological monitoring in French Polynesia, excluding the Mururoa
and Fangataufa sites. Monitoring covered seven islands from five archipelagoes, with 70% of theterritory's population concentrated in Tahiti. In response to the Fukushima accident, monitoring was
stepped up over a four-month period to determine whether releases from the damaged plant had any
impact on the population.
The implemented radioactivity measurements (gamma spectrometry measurements for 137Cs and 60Co
and alpha emitter measurements for Pu isotopes) cover almost the entire range of artificial
radionuclides likely to be detected in the considered environment.
Twenty-four samples were taken from the physical environment (air, water and sediments) and 153
from the biological environment, which included pelagic fish, lagoon fish and other lagoon products,
and land samples (fruit and vegetables, milk, various drinks). The sampling was used to address two
objectives :determine the levels of artificial radioactivity in all compartments of the environment and inmajor foodstuffs ;assess the additional dosimetric impact in this environmental situation: for the additional dose
due to ingestion, all the samples from Polynesian diet were taken into account. For external
exposure and inhalation, dose estimates are based on measurements from the physicalenvironment.
The radioactivity levels measured in 2011 were not markedly different from those measured in 2010.
The observed differences should be considered in light of the high natural variability, as was observed
for beef [5].
137

Cs was detected the most often. The maximum values obtained in 2011 are less than 0.4 Bq.kg -1 wet
for fish (pelagic and lagoon), and ten times lower for other lagoon products. These values show that the
Fukushima accident had no radiological impact on French Polynesia.
The values remain extremely low, in general less than 1 Bq.kg -1 wet, and often less than 0.01 Bq.kg-1
wet for solid foodstuffs. Six out of 153 results analyzed in 2011 were greater than 1 Bq.kg-1 of 137Cs wet:
5 for copra and 2.5 for taro from Tubuai, 3.3 for beef from Tahiti, 2.1 for lettuce and 1.3 for papaya
from Hiva Oa, and 1.4 for copra from Rangiroa (values in Bq .kg-1 wet).
No 60Co was detected in any sample.
When Pu activity levels were detected, they were extremely low. Beginning in 2011, Pu was measured
in three selected matrices [2]: the grouper and giant clam for lagoon environments, and copra for land
environments.
The Pu isotopes 238Pu and 239+240Pu were measured in very small concentrations in samples taken on six
islands (except for 238Pu, which was at the detection limit for the sample from Tahiti). All the otherresults for lagoon fish (grouper) and for copra, except for a trace of 239+240Pu detected in copra from
Mangareva, were below the detection limit.
Population exposure to this residual artificial radioactivity is mainly due to ingestion and external
exposure. Exposure via inhalation is negligible (direct fallout and resuspension of radioactive dust are
now extremely low, and practically undetectable).
No food product was a source of a dose through ingestion greater than 1 Sv.year-1. Some food productsthat are consumed in greater quantities may result in a dose of over 0.1 Sv.year-1. This was the case in2011 for beef from Tahiti that is also consumed in Tubuai, Mangareva and Maupiti, pork from Tahiti,
copra from Tubuai and Rangiroa, lagoon fish from Hao and Rangiroa, lettuce from Hiva Oa and papaya
from Mangareva.

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In general, the annual total dose that can be attributed to artificial radioactivity (Appendix IV), which isthe sum of external exposure, inhalation and ingestion doses, is comparable for all five archipelagoes
over the past twenty years. Overall, the average values for this period are approximately 3.5 µSv.year -1
for children and 4.5 µSv.year-1 for adults.
This order of magnitude comprises all three components of the "additional" dose, and can be comparedwith the total dose (natural and artificial) of 1,000 µSv per year on average in the South Pacific, as
established by the SPREP (South Pacific Regional Environment Program) in 1983 [13]. The "additional"
dose due to artificial radionuclides in French Polynesia therefore represents less than 0.5% of the total
average dose for the region.
In light of these findings, monitoring will evolve and diversify (radiological reports, nacre networks) tocontinue providing the most detailed information possible concerning radiological conditions in French
Polynesia and to meet the concerns of the local population, who are increasingly conscious ofenvironmental quality. Furthermore, discussions are already underway to adapt the estimation
methodologies for assessments both in French Polynesia and in France.
The concerns of the population were heightened after March 11, 2011 as to the radiologicalconsequences for the South Pacific following the accident at the Fukushima nuclear power plant. IRSN
employed its technical means in the French overseas departments and territories and in France toevaluate any possible radiological impact on the environment, and to inform the public of the resulting
observations and analyses. Specific sampling plans covering the atmospheric environment (air, rain) andterrestrial environment (grass, cow's milk) were implemented for several weeks after radioactive
release to the atmosphere stopped. All the results, together with their interpretation, and information
about the current situation in Japan were immediately made available on the site www.irsn.fr.
The monitoring of South Pacific marine environments will continue to be reinforced in 2012 to detect
any impacts due to the significant radioactive releases in the sea that occurred during the disaster inFukushima.

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report CP/URMPF/12.003 (2012) 63p.

[2]

Bouisset P., Bernagout S., Evolution de la stratégie de la surveillance de la radioactivité en
Polynésie française (Changes in strategy for radioactivity monitoring in French Polynesia).
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[3]

DEI work group. Analyse de l’impact de l’accident de Fukushima en France (métropole et
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[5]

Bouisset P., Bernagout S. Bilan de la surveillance de la radioactivité en Polynésie française
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Caledonia from March to May 2011). DEI/SESURE report 2011-40 (2012) 45p.

[6]D.J. Madigan, Z. Baumann, N.S. Fisher. Pacific bluefin tuna transport of Fukushima-derived
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Hermanspahn N., Environmental radioactivity in New Zealand and Rarotonga – Annual
Report 2010, NRL-F/90 (2011) 8p.

[8]Descamps B., Soil-to-plant, plant-to-milk and plant-to-meat transfers for the oxisols in
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