people and ionizing radiation - accueil - irsn...irradiation dose. these are necrotic and...

114 Scientific and Technical Report 2007 - IRSN

People and ionizing radiation3

3 PeoPle and ionizing radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3.1 "TranslaTional" research to improve the prognosis and treatment of radiation burns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.2 risk of childhood leukemia in the vicinity of nuclear installations 9

3.3 The eNVIRhoM PRogRaM: new knowledge in the field of human radiation protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.4 TRIage of exPosed PoPulaTIoNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.5 radiaTion proTecTion in the workplace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

newsflashnewsflashnewsflashnewsflashnewsflashnewsflash

3.6 diagnosTic reference levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.7 Whole body counT intercomparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.8 KeY daTes: Dissertations defended and other major events . . . . . . . . . . . . . . . . . 39

IRsN - Scientific and Technical Report 2007 115

116 Scientific and Technical Report 2007 - IRsN

PeoPle and ionizing radiation

Assessing the health risks associated with the use of ion-izing radiation in the industrial, research and medical sec-tors is an ongoing scientific and technical challenge. Despite the existence of an extensive body of knowledge and an interna-

tional system with a broad consensus among international com-

missions in the field, maintaining expertise in human radiation

protection requires constant technical renewal and the continuation

of dedicated research programs. Unlike other international structures

concerned with human radiation protection, IRSN has opted to

maintain the highest possible technical standards at its reference

metrology laboratories and to enhance its academic expertise by

developing specific experimental research activities within its

laboratories.

The following articles describe some of the main scientific activities

of IRSN's Human Radiation Protection Division (DRPH) in the

various areas of accident and low-dose radiation protection:

medical response after a radiation accident, and population

triage based on a dosimetric approach;

health effects other than cancer after chronic contamination

with radionuclides;

risk of childhood leukemia in the vicinity of nuclear installations;

methodology for dosimetry at the workplace;

dose level mapping for diagnosis in radiotherapy and nuclear

medicine facilities;

whole body count intercomparison between laboratories.

The two articles on medical assistance in the event of accidental

irradiation illustrate the quality of IRSN's expertise and show how

the Institute's wide range of methodology was used to support

the hospital structures where victims were treated.

Through the creation of a scientific , clinical and operational

network including the Percy Military Hospital, with its burn treat-

ment center and plastic surgery and hematology services, the

Military Blood Transfusion Center, Saint-Antoine Hospital and

IRSN, French expertise in the medical management of radiation

accidents and in research and development relating to new

therapeutic methods such as adult stem cell grafting is acknowl-

edged all over the world.

The article on the health-related aspect of the ENVIRHOM research

program discusses an experimental program that attempts to answer

one of the most controversial questions in the field of radiation

protection: Is the international radiation protection system (based

mainly on the epidemiological studies of Hiroshima and Nagasaki)

robust enough with regard to continuous and chronic environmen-

tal exposure to radionuclides? Two models were studied: uranium,

which is a radionuclide representative of heavy radioactive metal

contamination, where both chemical and radiological toxicity must

be considered, and cesium, a major radionuclide in the event of a

nuclear accident, as demonstrated by the Chernobyl accident.

Patrick GourmelonHuman Radiation Protection Division


esis of infection due to the mixing of populations around nuclear

sites, it is still difficult to determine the causes of the excess of

leukemia cases observed locally near such sites, due to insufficient

knowledge of the risk factors concerning childhood leukemia. Large-

scale national or international analytical studies should therefore

be conducted in this field.

Experimental results show that biological effects, apart from cancer,

observed during chronic exposure via ingestion cannot be extrapo-

lated from knowledge of acute exposure effects. These biological

effects concern the main physiological functions of the body and

depend on the type of contaminant (uranium or cesium). Whether

these biological responses are simply adaptive responses of the

body to environmental stress or whether they are related to a

genuine health impact remains an open issue.

The article concerning the risks of childhood leukemia in the vicin-

ity of nuclear installations addresses a recurrent question on the

effects of low-dose exposure. For over 20 years now, epidemiologists

in nuclear countries have attempted to confirm or disprove the

existence of a causal relation between the aggregates of leukemia

cases observed in the vicinity of certain sites and the environmen-

tal impact of the nuclear installations present in these sites. A joint

effort by the INSERM and IRSN has led to the first ever epidemio-

logical study in France on the incidence of childhood leukemia in

the vicinity of nuclear sites.

The completion of such studies and the publication of their results

help bring social issues into radiation protection appraisal. Since

this article was written, a German study published in late 2007 has

pointed to a high risk of leukemia in children under 5 years of age

living less than 5 km from German nuclear plants. Following the

publication of this study, the Nuclear Safety Authority asked IRSN

to conduct a critical review of studies published on the subject.

This analysis shows that there are many types of epidemiological

studies and that they often exhibit significant methodological

limitations, making it difficult to prove any relation of cause and

effect. Although there seems to be most support for the hypoth-


3. 1

how can early diagnosis and prognosis be improved?

Conventional burn prognosis techniques in current use, such as

infrared thermography or doppler laser techniques, can neither detect

radiation burns more than two days after irradiation nor predict how

they will evolve. IRSN proposes two lines of research to overcome

these limitations.

The first line of research consists in acquiring tools to distinguish

between irradiated and non-irradiated skin regions as soon as pos-

sible. The research conducted by IRSN in collaboration with the

University of Créteil and the Ecole Polytechnique has led to the

development of a new experimental system based on the use of

optical techniques (polarimetry in particular) to assess the biophysi-

cal properties of the skin sample. We have shown that speckle fields

are novel mathematical tools allowing in vivo and non-invasive distinc-

tion between irradiated and healthy tissues during the clinically silent

latency period of the radiation burn (Figure 1). Histological studies

have correlated measured physical parameters with the structural

modifications in the skin generally observed after irradiation: edema

formation, thickening of the epidermis, collagen deposition, changes

Marc Benderitter, Radia Iamarat, Odile Carvalho, Olivier GuipaudRadiopathology Laboratory

The past few years have seen an increase in the frequency of localized irradiation accidents due to overdosage

during radiotherapy treatment (Poland 2001) or lost radioactive sources (Georgia 2001, Chile 2005, Dakar 2006).

Although the number of people concerned is limited, the clinical treatment of radiation burns is particularly

complex and the evolution of such lesions may be catastrophic. France has acquired widely acknowledged

expertise in dealing with localized irradiation accidents, based on highly specialized medical services (such as

the Burn Treatment Center at the Percy Military Hospital).

The pathogenesis of the cutaneous effects of ionizing radiation is well documented, but the medical response

for this type of pathology is extremely complex and delicate. Skin exposure to doses above 25 Gy represents the

most critical situation, due to necrosis of the cutaneous tissue associated with successive waves of inflamma-

tion. The clinical treatment of such burns highlights two problems: a) the extreme difficulty in making a reliable

prognosis of how lesions will evolve, and b) the limited range of therapeutic tools available. Improved medical

management of these lesions requires reliable prediction - at the earliest possible stage - of the evolution of

cutaneous damage so that the most suitable therapeutic strategy can be rapidly chosen.

"TRaNslaTIoNal" ReseaRch to improve the prognosis and treatment of radiation burns

People and ionizing radiation


3. 1

in vascularization. These experiments were performed using the pig

as experimental model under a contract with the DGA. A patent

application has been filed.

The second line of research is aimed at predicting the evolution

and severity of cutaneous lesions from a simple blood sample. To

achieve this objective, the Radiopathology Laboratory is develop-

ing an approach based on a proteomic analysis. Proteomics is a

new, fast-growing technology used to separate and measure

quantitative and qualitative variations in thousands of proteins

at the same time. The most "interesting" proteins can be rapidly

identified by mass spectrometry. This technology is very promis-

ing for the identification of diagnosis and prognosis markers, or

even treatment response markers, for numerous pathologies

(cancers, neurodegenerative diseases, autoimmune diseases, car-

diovascular diseases, etc.). Drawing on preclinical and clinical

studies on humans, the laboratory develops tools to identify

biomarkers indicating the severity of the evolution of radiation-

induced lesions.

A model of localized skin irradiation in mice has been designed

to study the development of cutaneous irradiation severity mark-

ers that could be used in humans [Guipaud et al., 2007]. In this

model, the mouse skin is stretched so that it can be irradiated

without affecting the rest of the organism (Figure 2a). Lesions of

increasing severity are experimentally induced by modulating the

irradiation dose. These are necrotic and non-necrotic lesions that

may or may not be repaired (Figure 2b). The model and pro-

teomic analysis tools were developed in the laboratory based on

a first series of experiments using a single irradiation dose of

40 Gy. This analysis, conducted on serums from blood samples

taken at various times following irradiation (from 24 hours to 1

month), showed that, based on the hundreds of different proteins

viewed, changes in protein profiles could be detected as of the

first 24 hours, i.e. long before the clinical manifestation of the

lesions, and up to 1 month after irradiation (Figures 3a and 3b).

The 20 main proteins varying after irradiation (approximately 60

protein stains) were identified by mass spectrometry (collabora-

tion with the Biological Mass Spectrometry and Neuroproteomics

Laboratory of the École supérieure de physique et de chimie indus-

trielles in Paris). Quantitative variations in proteins involved in

acute-phase inflammatory response (haptoglobin, hemopexin,

apolipoprotein A1, etc.), in coagulation (antithrombin III, throm-

bospondin 1, etc.) and in cell defense systems (gelsolin, peroxy-

redoxin 2, etc.) were detected as from the day after irradiation.

All the proteins identified during this phase of the project provide

a preliminary basis for the subsequent identification of diagnos-

tic and/or predictive markers of cutaneous lesion severity in

humans.

Two clinical studies are currently in progress. One is aimed at

finding a skin sensitivity signature during breast cancer radio-

therapy (collaboration with the Oscar-Lambret Center in Lille) to

predict the potential skin complications observed in 30% of

J22 J29 J38 J45 J52 J58 J69 J78 J84 J94 J101 J108

0 Gγ40 Gγ

Extension of moist desquamation

Regression of moist desquamation

Edema

Moist desquamation

0.65

Hurst coefficient

0.7

0.75

0.80

0.85

0.9

F Figure 1 a: Photographs of the irradiated area and control area. b: Analysis of the main components of the physical measurements taken on a pig irradiated with a local dose of 40 Gy. The red dots correspond to measurements taken in the irradiated area, and the blue dots to those taken in the non-irradiated area. The healthy area and the irradiated area can be distinguished as of day 58, before the first clinical signs appear (see the photographs above, where no clinical signs are visible on day 69). c: Linear representation of the HURST coefficient (one of the speckle parameters) as a function of time after irradiation.

a c

b


3. 1

the initial damage: complete tissue repair (scarring), pathological

tissue repair, if the lesion evolves toward a cutaneous fibrosis process

in the long term, or absence of tissue repair, in which case tissue

necrosis occurs, calling for surgical action to limit the growth of

the lesion. Tissue repair is the result of dynamic integration of

numerous biological processes. These processes simultaneously

involve the extracellular matrix of the injured tissue, cytokines and

growth factors that modulate the various cell compartments, the

cells making up the skin tissue, and the infiltrated blood cells. This

system of cell/cytokine/matrix interactions and feedback is crucial

to skin tissue repair. Defective repair or non-repair processes are

caused by a deregulation of these biological interactions.

Given the importance of this biological context for the evolution

of radiation burns, research in 2007 chiefly focused on inflammation-

related mechanisms. A relationship between chronic inflammation

and radiation-induced oxidative stress was demonstrated in humans

after localized skin irradiation, adopting a "broad-spectrum" approach

(DNA chips), [Benderitter et al., 2007 ; Case report: Georgia accident,

2001]. In vivo experiments also demonstrated how initiating and

maintaining the activation of the vascular endothelium is important

with regard to the evolution of lesions following localized skin

irradiation. Activation of the vascular endothelium controls the

migration of inflammatory cells from the blood compartment to

the injured tissues. A pharmacological strategy aimed at control-

patients. The other sets out to identify a protein signature that

could be used to predict the occurrence of radiation proctitis in

humans after the treatment of colorectal tumors.

Improving therapeutic tools and strategies

The development of new therapeutic strategies calls for better

knowledge of the mechanisms causing the lesion, as well as those

involved in skin repair after irradiation.

cutaneous radiopathology

Localized exposure to high doses is first characterized by surface

lesions caused by total destruction of the epidermis, with interphase

keratinocyte necrosis, rupture of the dermo-epidermal junction,

destruction of the micro-vascularization of the papillary dermis,

and gradual occlusion of vessels. Perivascular inflammatory infiltra-

tion soon becomes significant. A second, later phase is observed

following the modification of the vascular network located deep in

the muscle, which results in ischemic necrosis in the muscle mass

and deep ulceration.

Peripheral scarring penetrating the injured regions can be observed.

This is due to a cascade of complex biological responses, with the

following eventual effects according to the intensity and extent of

0,5

1

1,5

2

2,5

3

3,5

4

Lesion score (arbitrary unit)

Time after irradiation0 7 14 21 28

2 Gy10 Gy20 Gy40 Gy80 Gy

NI80 Gy

40 Gy

20 Gy

10 Gy2 Gy

Erythema

Desquamation

Necrosis

Side view

Top view

Figure 2 Animal model for the study of radiation-induced skin lesions. (a) The skin is stretched so that it is within the irradiation field. (b) The lesions are evaluated on a scale expressed in arbitrary units. The severity of the lesions depends on the dose.

a b



3. 1

The administration of hMSCs could be an efficient therapeutic

treatment for the early phases of radiation-induced skin syn-

drome.

initial clinical successes

In December 2005, one of three workers in contact with an

iridium-192 source suffered severe hand and buttock exposure.

In view of the severe evolution of the lesions, the worker was

transferred to the Percy Military Hospital in France two weeks

after the accident.

The buttock lesion was operated on in early January 2006 and the

patient was given an innovative treatment in which hMSCs taken

from his own bone marrow and grown in the laboratory were

administered locally [J.J. Lataillade et al., 2007].

ling this vascular activation through the use of statins has con-

firmed the significance of radiation-induced vascular dysfunction

and the chronic nature of inflammation in the development of

radiation-induced skin lesions.

new hope from cell therapy

Many studies by our group and others suggest that adult stem

cells, especially human mesenchymal stem cells (hMSCs), could

be used to repair numerous types of tissue. It has been demon-

strated that hMSCs are capable of reducing skin lesions in immu-

nologically tolerant mice irradiated in the leg region [François et

al., 2007]. hMSCs were injected intravenously 24 hours after

irradiation in a NOD_SCID mouse model. Skin samples were taken

3 to 8 weeks after irradiation and checked for human cells and

used to study the severity of radiation-induced lesions and scar-

ring processes. The level of radiation-induced cutaneous lesions

was found to be considerably reduced in mice treated with hMSCs.

The clinical scores used to study the evolution of skin lesions

improved significantly and scarring was faster compared with

untreated mice. These results suggest that hMSCs are capable of

migrating to the area of the skin damaged by ionizing radiation

and that they accelerate the tissue repair process, thereby limit-

ing radiation-induced tissue complications.

Figure 3 Two-dimensional analysis of serum proteins in mice irradiated with a 40 Gy dose to the skin. (a) The proteins of the control specimen are marked with Cy3 (shown in green), those of the irradiated specimen are marked with Cy5 (shown in red) and separated within the same gel to increase analysis efficiency. Each protein is represented in the gel by a "spot" that can be quantified in terms of relative abundance. The two images (green and red) can be superimposed for visual identification of the most significant differences. (b) When processing a large number of samples, image analysis and statistical analysis are carried out to select the spots that vary in a statistically significant manner. This graph shows the number of varying spots at each point studied after irradiation. The curve of the lesion score has been superimposed (in red). The detection of proteins that vary during the silent period, i.e. before day 7 or even the day after irradiation, is particularly noteworthy.

Number of varying spots

Lesion score

Expression rateControl

Superposition

Irradiated

1 5 14 21 33

0

20

40

60

80

100

120

140 3

2,5

2

1,5

1

0,5

0

0

Taux d'expressionx 21,5 x 21,5 x 2x 2

a b


3. 1

The patient returned to his country a few months after the accident

and has since shown no signs of recurrence (Figure 4).

Cell therapy shows great promise as a therapeutic strategy for the

treatment of radiation-induced lesions in the field of regenerative

medicine. The first clinical successes over the past two years have

been behind the initiation of a new cell therapy research program

with partners in the clinical field. The aim of the program is to study

the part played by adult stem cells in functional and structural

regeneration for radiation-induced tissue damage. The study will

initially focus on the use of hMSCs for regenerating skin tissue and

the gastrointestinal system. However, depending on results obtained

elsewhere, it could be extended to other types of adult stem cells,

e.g. adipocyte stem cells.

Figure 4 Treatment and evolution of buttock lesion, by dosimetry-guided surgery and autologous mesenchymal stem cell therapy (Chile accident, 2005).

Reference

M. Benderitter, M. Isoir, V. Buard, V. Durand, C. Linard, M. C. Vozenin-Brotons et al., Collapse of skin antioxidant status during the subacute period of cutaneous radiation syndrome: a case report. Radiat Res, 167 : 43-50, 2007.

B. G. Douglas & J. F. Fowler, The effect of multiple small doses of X rays on skin reactions in the mouse and a basic interpretation. Radiat Res, 66 : 401-426, 1976.

S. Francois, M. Mouiseddine, N. Mathieu, A. Semont, P. Monti, N. Dudoignon, A. Sache, A. Boutarfa, D. Thierry, P. Gourmelon & A. Chapel, Human mesenchymal stem cells favour healing of the cutaneous radiation syndrome in a xenogenic transplant model. Ann Hematol., 86(1) : 1-8, 2007.

O. Guipaud, V. Holler, V. Buard, G. Tarlet, N. Royer, J. Vinh & M. Benderitter, Time-course analysis of mouse serum proteome changes following exposure of the skin to ioniz-ing radiation. Proteomics, 7(21) : 3992-4002, 2007.

J.-J. Lataillade, C. Doucet, E. Bey, H. Carsin, C. Huet, I. Clairand, J.-F. Bottollier-Depois, A. Chapel, I. Ernou, M. Gourven, L. Boutin, A. Hayden, C. Carcamo, E. Buglova, M. Joussemet, T. de Revel & P. Gourmelon, New approach to radiation burn treatment by dosimetry-guided surgery combined with autologous mesenchymal stem cell thera-py. Regen Med., 2(5) : 785-94, 2007.


current context of epidemiological studies on the risk of childhood leukemia in the vicinity of nuclear installations

Since 1984, numerous epidemiological studies have been devoted to

the risk of childhood leukemia in the vicinity of nuclear sites [Laurier et

al. 1999]. Local studies have revealed abnormally high concentrations

of leukemia cases near such sites, particularly near the Sellafield and

Dounreay reprocessing plants in the United Kingdom and, more recent-

ly, near the Krümmel plant in Germany [Laurier et al. 2002]. However,

studies conducted simultaneously around several different sites outside

France do not show a higher incidence of childhood leukemia around

nuclear sites than elsewhere [Comare 2005].

In France, an excess of leukemia among people under 25 years of

age was suggested in 1995 near the La Hague spent nuclear fuel

reprocessing plant [Viel et al. 1995]. A detailed radio-ecological

study coordinated by IRSN was conducted as a result [GRNC 1999,

Laurier et al. 2000, Rommens et al. 2000]. More recent analyses of

leukemia incidence in the same region do not show a globally

significant excess in people under 25 years of age, although the

frequency of leukemia cases remains high, particularly due to a

significant number of cases among children between 1 and 6 years

of age [Guizard et al. 2001]. However, the incidence of childhood

leukemia could not be studied throughout France as there was no

national register, and only mortality studies covered several sites

simultaneously [Hattchouel et al. 1995].

national study of childhood leukemia incidence in the

vicinity of nuclear sites

A national incidence study was carried out under a health and

environmental contract, coordinated by IRSN [Laurier et al. 2003].

This epidemiological study was carried out in collaboration with

INSERM U754, using the database of the national registry of child-

hood leukemia [Clavel et al. 2004]. The study considered 29 basic

nuclear installation sites, located all over Metropolitan France:

nineteen EDF NPPs, the EDF Superphenix breeder reactor in Creys-

Malville, six CEA research centers, the AREVA NC reprocessing plant

in La Hague, the AREVA NC/CEA site in Marcoule, and the FBFC

Dominique LaurierIonizing Radiation Epidemiology Laboratory

The question of an increased risk of childhood leukemia in the vicinity of nuclear sites has been raised repeatedly

for more than 20 years. In collaboration with the INSERM, IRSN has conducted in France the first ever nation-

wide epidemiological study, based on the database of the national registry of childhood leukemia. This research

work has led to three publications [White-Koning et al. 2004, Evrard et al. 2005, and White-Koning et al. 2006].

The results provide some answers to the questions raised by the population concerning risks in the vicinity of

nuclear sites. They also form a scientific reference that could be used in the future to put into perspective any

aggregates of localized leukemia cases that might be observed.

RIsK of chIldhood leuKeMIa in the vicinity of nuclear installations

3. 2


3. 2

A local significant excess of cases was recorded near the Chinon

and Civaux NPPs and a significant deficit was observed near the

Bruyères-le-Chatel, Saclay and Fontenay-aux-Roses sites. Given the

large number of statistical tests conducted, these results are quite

consistent with a random effect, and no statistically significant

results remained once a multiple test correction method had been

applied [White-Koning et al. 2004 and 2006].

supplementary study with geographic zoning of population exposure

Like most descriptive studies on health risks near industrial sites,

this study was based on a definition of concentric zones around

the sites. The risk was analyzed in the absence of any information

on potential exposure levels. Yet tools and data to estimate the

doses received by neighboring populations due to radioactive release

do exist in the nuclear sector [Chartier et al. 2002].

A second study was therefore conducted to assess the feasibility

and advantages of a geographic zoning system for measuring

ionizing radiation exposure of populations living near nuclear sites

in France [Evrard et al. 2006]. Zones were defined on the basis of

isodose curves estimated by modeling the transfer of radionuclide

release to the different compartments of the environment. The

methodology is described in two reports [Morin et al. 2002 and

2003]. Only gaseous releases (atmospheric releases through stacks)

were considered. This is because the dose due to liquid releases

(to the sea or rivers) depends mainly on water use (fishing, con-

sumption of products from sites contaminated by irrigation with

river water, etc.) and does not follow geographic zoning logic. Doses

were calculated using FOCON96, a computer code that assesses

the impact of radioactive gaseous releases from nuclear facilities

under normal operating conditions [Rommens et al.1999]. The data

required to characterize the sites (metrology, hydrological network)

and releases (spectra, levels) was obtained from site effluent release

and water intake permit applications, impact studies, or regula-

tory documents available at IRSN. Effluent release data related to

recent periods (post 1995). Dose estimates considered all main

exposure pathways: ingestion, inhalation, external exposure.

Assumptions had to be made regarding the release height consid-

ered, the lifestyle of populations, and the quantities of certain

radionuclides (carbon-14 in particular) actually released. Based on

this model, isovalue curves of bone marrow doses were plotted

over a 40 km2 zone centered on each site. Each of the districts

included in these zones was classified according to the mean

estimated dose (Figure 2).

fuel manufacturing plant in Romans-sur-Isère (FBFC) (Figure 1). The

study covered all leukemia cases diagnosed between 1990 and 1998

in children aged between 0 and 14 years and living less than 20 km

from one of the 29 sites considered. Concentric zones with a

radius of 5 km were defined around each of these sites (0-5, 5-10,

10-15 and 15-20 km). The number of children aged between 0 and

14 years during the period 1990 to 1998 was determined in each

of these zones by interpolation of census data. The number of cases

expected in each zone was calculated from national leukemia rates

and local population figures for each age group. The relative risk of

leukemia in each zone was estimated using the standardized inci-

dence ratio method, i.e. the ratio of the number of cases observed

to the number of cases expected. The 95% confidence interval

associated with this estimate was systematically calculated. Several

statistical methods were applied to determine whether the relative

risk of leukemia varied with the distance from nuclear sites.

Supplementary analyses were also performed based on age group,

type of site and NPP power output. A correction method was used

to take into account the multiplicity of some tests.

A total of 690 cases were observed within a 20 km radius around

the 29 nuclear sites considered, as compared to 729.1 cases expect-

ed (standardized incidence ratio = 0.92; 95% confidence interval

= [0.85 — 0.99]). The results for each site are listed in Table 1. The

analyses by age group, installation type, electric power output or

commissioning date (for NPPs) showed no excess risk. No decrease

in relative risk as a function of distance from site was observed.

Gravelines

Chooz Cattenom

Nogent

DampierreBelleville

GrenobleRoman

CruasTricastin

Flamanville

St-Laurent

Chinon

Civaux

Blayais

Golfech

Valduc

La Hague Paluel

FontenaySaclay

Bruyère

Penly

Fessenheim

Bugey

Cadarache

St-AlbanCreys-Malville

Marcoule

EDF plantsCEA research centers

Others

Figure 1 Location of sites considered in the study of childhood leukemia incidence in the vicinity of French nuclear installations.



3. 2

nuclear sites(yeara, power outputb)

0-5 km 5-10 km 10-15 km 15-20 km Total

O E O E O E O E O E

Nuclear power plants (NPPs)

Belleville (1987, 2600) 0 0.26 0 0.53 2 1.44 3 1.05 5 3.28

Bugey (1971, 3600) 0 0.21 2 2.62 5 3.67 7 5.58 14 12.07

cattenom (1986, 5200) 0 0.92 5 5.95 3 4.25 3 6.48 11 17.61

chinon (1963, 3600) 1 0.68 6 1.47 2 0.94 5 3.55 14 6.64

chooz (1966, 2800) 0 0.59 0 0.75 0 0.54 0 0.01 0 1.9

civaux (1997, 2800) 0 0.08 1 0.51 1 0.88 5 1.48 7 2.95

cruas (1983, 3600) 0 0.48 3 3.21 4 2.2 3 3.18 10 9.07

dampierre (1980, 3600) 0 0.38 2 1.48 1 1.02 0 1.07 3 3.95

fessenheim (1977, 1800) 0 0.36 0 0.68 0 0.88 0 3.59 0 5.51

flamanville (1985, 2600) 0 0.29 1 0.63 0 0.53 1 1.02 2 2.48

golfech (1990, 2600) 0 0.53 1 0.57 1 0.87 2 2.37 4 4.33

gravelines (1980, 5400) 1 1.67 2 2.03 6 6.49 5 10.12 14 20.31

le Blayais (1981, 3600) 0 0 1 1.09 2 1.55 1 1.28 4 3.91

Nogent (1987, 2600) 1 0.55 2 0.6 0 0.77 1 2.98 4 4.9

Paluel (1984, 5200) 0 0.21 1 1.17 0 0.69 2 1.26 3 3.34

Penly (1990, 2600) 0 0.42 1 0.85 3 4.17 5 2.21 9 7.65

saint-alban (1985, 2600) 4 1.69 4 2.56 0 1.88 4 9.59 12 15.72

saint-laurent (1969, 1800) 1 0.43 0 1.28 2 1.36 2 1.41 5 4.48

Tricastin/Pierrelatte (1980, 3600) 0 0.88 2 3.17 1 2.09 1 0.79 4 6.92

Total npps 8 10.64 34 31.13 33 36.21 50 59.03 125 137.01

SIRc [CI 95%]d 0.75 [0.32-1.48] 1.09 [0.76-1.53] 0.91 [0.63-1.28] 0.85 [0.63-1.12] 0.91 [0.76-1.09]

other nuclear sites

cadarache (1963) 0 0.05 1 0.7 1 0.86 2 2.49 4 4.09

creys-Malville (1985) 1 0.19 1 0.94 1 0.66 5 2.41 8 4.2

grenoble (1956) 14 14.47 9 11.1 5 4.13 10 7.48 38 37.18

la hague (1967) 2 0.31 0 0.43 1 0.73 2 5.22 5 6.69

Marcoule (1956) 0 0.19 5 4.89 5 2.11 1 1.95 11 9.14

Romans-sur-Isère (1962) 2 3.79 1 0.76 3 2.32 2 2.03 8 8.9

Valduc (1962) 0 0.03 0 0.09 0 0.21 0 0.64 0 0.96

Bruyères/saclay/fontenay(1955/1950/1948)

38 45.43 114 124.25 171 203.54 148 147.68 471 520.91

subtotal (npps and other sites except b/s/f)

27 29.68 51 50.05 49 47.22 72 81.24 199 208.18

SIRc [CI 95%]d 0.91 [0.60-1.32] 1.02 [0.76-1.34] 1.04 [0.77-1.37] 0.89 [0.69-1.12] 0.96 [0.83-1.10]

ToTal (npps and other sites) 65 75.11 165 174.3 220 250.76 220 228.92 670 729.09

SIRc [CI 95%]d 0.87 [0.67-1.10] 0.95 [0.81-1.10] 0.88 [0.77-1.00] 0.96 [0.84-1.10] 0.92 [0.85-0.99]

a : Year of commissioning

b : Electric power output (in MWe) = number of reactor units multiplied by the power output of each unit

c : SIR = standardized incidence ratio

d : [CI 95%] = 95% confidence interval of the standardized incidence ratio

e : B/S/F = Bruyères/Saclay/Fontenay

Table 1 Number of leukemia cases observed (O) and expected (E) in children aged 0 to 14 years, living less than 20 km from 29 nuclear sites in France, as a function of distance (1990-1998) (from White-Koning et al. 2004).


3. 2

conclusions of the two studies

The two studies presented above show no increase in leukemia

incidence in children aged 0 to 14 years living near the French

nuclear installations considered. Results are consistent with

those obtained in multisite studies conducted in other parts of

the world [Laurier et al. 2002, Comare 2005].

The national incidence study conducted under the health and

environment contract provides the first analysis of the risk of

leukemia in the vicinity of French nuclear sites, based on mor-

bidity data [White-Koning et al. 2004]. Given that the leukemia

remission rate in children is approximately 75%, this risk indi-

cator is far more relevant than the mortality rate. In addition,

this study covered a significant number of cases (several hun-

dred), thereby reducing the interpretation difficulties associated

with the very low effective doses observed in local studies

(which often concern a few individual cases or a few tens of

cases). Nevertheless, it is important to bear in mind the method-

ological limitations inherent in the approach used (data

aggregated by geographic unit, population migration not taken

into account, absence of exposure data, etc.). Consequently, the

results of this study should only be considered in the light of

their descriptive interest. The results of this study and, more

generally, data contained in the database of the national regis-

try of childhood leukemia, form a general reference that could

be used in the future to put into perspective any aggregates of

localized leukemia cases that might be observed.

The supplementary study, based on geographic zoning taking

into account gaseous releases from facilities, should be consid-

ered as a sensitivity study [Evrard et al. 2006]. It confirms the

overall results of the previous study. The objective was to obtain

a method for comparing dose estimates with health surveillance

data. Results illustrate the low dose values attributable to gas-

eous releases due to routine operation of the facilities considered,

and the limitations of the conventional approach based on a

division into concentric zones. Nevertheless, the results of this

supplementary study should be interpreted with caution. The

estimated dose values can be used to compare release-induced

doses with those due to other sources of environmental expo-

sure. They should never be considered as individual dose

estimates or used to estimate a dose-risk relationship. Their sole

purpose is to define a geographic zoning method that takes into

account the local characteristics of the sites studied more effec-

tively than the concentric circles method.

Collaboration between the INSERM and IRSN made it possible

to conduct (in France) the first ever epidemiological study on

childhood leukemia incidence around nuclear sites. The results

are purely descriptive and do not provide any fresh insight into

This zoning method was applied to the 23 nuclear sites in

operation between 1990 and 2001. Two important points should

be stressed regarding dose estimate results:

the estimated doses were very low: bone marrow dose ranged

from 0.1 to 1.3 µSv per year in all the 2,017 districts located

within the 40 km2 zones centered on the various sites (average

of 0.2 µSv);

the zones defined by the isodose curves were sometimes very

remote from concentric circles (particularly for sites located

near the sea and in the Rhone valley) (Figure 2).

The incidence study considered all leukemia cases in children

under 15 years of age between 1990 and 2001 near these 23

nuclear sites. A total of 750 cases were observed in the 40 km2

zones around each site, as compared to 795.0 cases expected

(standardized incidence ratio = 0.94; 95% confidence interval

= [0.88 – 1.01]). No trend emerges from the classification of

the districts according to dose level. The results for each site are

listed in Table 2. The number of local excesses and deficits (one

excess and two deficits) is compatible with random variability,

and no statistically significant results remain once a multiple

test correction method has been applied. Supplementary analy-

ses (by site type, leukemia type, age group) reveal no specific

results [Evrard et al. 2006].

Courbes d’isodoses Classification of each district as a function of mean dose rate

10

20

30

40 km

Figure 2 Illustration of the zoning method based on models of the transfer of gaseous releases from nuclear installations to the environment.



3. 2

nuclearsites

estimated dosea due to gaseous releases (µsv/year)

no < 0.045 0.045-0.072 0.072-0.316 0.316-1.0 >= 1.0 Total

com d O E O E O E O E O E O E

Nuclear power plants (NPPs)

Belleville 58 1 0.79 2 0.63 3 2.82 0 0.34 0 0.11 6 4.68

Bugey 132 9 8.46 6 5.11 15 10.70 1 1.11 0 0.39 31 25.77

cattenom 122 4 1.48 1 1.92 13 14.83 6 8.69 0 0.58 24 27.50

chinon 88 9 4.85 1 1.11 7 3.30 3 1.31 0 0.32 20 10.90

chooz 22 1 0.52 0 0.30 1 0.51 0 0.07 0 0.03 2 1.44

civaux 58 3 0.99 0 0.19 0 0.51 0 0.03 0 0.02 3 1.75

cruas 93 7 4.83 1 0.43 4 2.69 2 1.98 2 3.34 16 13.26

dampierre 51 2 0.77 0 1.50 4 3.12 0 0.49 0 0.15 6 6.02

fessenheim 69 17 31.86 0 0.53 0 1.35 0 0.20 0 0 17 33.94

flamanville 27 0 0.43 0 0.57 0 0.36 2 0.54 0 0.32 2 2.22

golfech 110 1 2.32 1 3.57 2 3.40 1 0.52 0 0.54 5 10.35

gravelines 63 7 12.05 2 1.35 19 18.75 1 4.66 1 1.49 30 38.30

le Blayais 89 1 0.72 0 1.69 5 3.34 1 1.09 0 0 7 6.84

Nogent 121 2 2.84 0 2.23 1 1.78 2 0.90 0 0 5 7.75

Paluel 127 0 1.34 1 0.98 4 4.66 0 0.50 0 0.54 5 8.01

Penly 133 7 4.20 3 1.81 5 5.36 0 0.36 0 0.33 15 12.06

saint-alban 143 16 16.18 1 1.62 8 7.84 3 2.28 0 0.32 28 28.24

saint-laurent 77 12 7.87 3 2.47 4 3.08 1 0.47 0 0.11 20 13.99

Total npps 1 583 99 102.49 22 28.03 95 88.39 23 25.54 3 8.58 242 253.03

SIRb [CI 95%]c 0.97 [0.79-1.18] 0.78 [0.49-1.19] 1.07 [0.87-1.31] 0.90 [0.57-1.35] 0.35 [0.07-1.02] 0.96 [0.84-1.08]

Pierrelatte/Tricastin 78 2 4.10 0 1.66 3 6.26 1 2.45 0 0 6 14.47

Total npps+ pierrelatte/Tricastin

1 661 101 106.59 22 29.69 98 94.65 24 27.99 3 8.58 248 267.49

SIRb [CI 95%]c 0.95 [0.77-1.15] 0.74 [0.46-1.12] 1.04 [0.84-1.26] 0.86 [0.55-1.28] 0.35 [0.07-1.02] 0.93 [0.82-1.05]

other sites

cadarache 47 7 6.18 1 0.90 3 1.52 0 0.14 0 0 11 8.74

la hague 43 0 0 0 0 0 0 10 8.15 3 1.81 13 9.97

Romans-sur-Isère 114 20 24.68 0 0 0 0 0 0 0 0 20 24.68

saclay 242 114 124.88 238 238.45 102 114.96 3 5.32 1 0.52 458 484.13

subtotal (npps and other sites except saclay)

1 865 128 137.45 23 30.59 101 96.16 34 36.28 6 10.39 292 310.88

SIRb [CI 95%]c 0.93 [0.78-1.11] 0.75 [0.48-1.13] 1.05 [0.86-1.28] 0.94 [0.65-1.31] 0.58 [0.21-1.26] 0.94 [0.83-1.05]

Total (nppsand other sites) 2 107 242 262.34 261 269.04 203 211.12 37 41.60 7 10.91 750 795.01

SIRb [CI 95%]c 0.92 [0.81-1.05] 0.97 [0.86-1.10] 0.96 [0.83-1.10] 0.89 [0.63-1.23] 0.64 [0.26-1.32] 0.94 [0.88-1.01]

a : Estimated bone marrow dose (microsieverts per year)

b : SIR = standardized incidence ratio = O/E

c : [CI 95%] = 95% confidence interval of the standardized incidence ratio

d : Number of districts considered

Table 2 Number of leukemia cases observed (O) and expected (A) in children aged 0 to 14 years living in the vicinity of 23 nuclear sites in France, as a function of estimated dose due to gaseous releases from facilities (1990-2001) (from Evrard et al. 2006)


3. 2

the effects of ionizing radiation. They do, however, provide

answers to the questions raised by the public regarding poten-

tial risks around nuclear sites. People living near nuclear

installations ask many questions concerning the potential risks

associated with these facilities. These questions are often

expressed by local information committees (CLI). Through such

studies and the extensive distribution of their results, society at

large can gain easier access to expertise in the field of radiation

protection. In 2007, the national association of local information

committees (ANCLI) and the national health watch institute

(INVS) began to work together on a general approach to issues

regarding the health impact of nuclear installations and the suit-

ability of methodological tools.

Reference

M. Chartier, A. Desprès, S. Supervil, D. Conte, P. Hubert, A. Oudiz, D. Champion. Guide d’examen pour l’étude de l’impact radiologique d’une installation nucléaire de base (INB) fournie à l’appui des demandes d’autorisation de rejets. Rapport IRSN/02-24. Institut de radioprotection et de sûreté nucléaire, Fontenay-aux-Roses, octobre 2002.

J. Clavel, A. Goubin, M.F. Auclerc, A. Auvrignon, C. Waterkeyn, C. Patte, A. Baruchel, G. Leverger, B. Nelken, N. Philippe, D. Sommelet, E. Vilmer, S. Bellec, F. Perrillat-Menegaux, D. Hemon. Incidence of childhood leukemia and non-Hodgkin’s lymphoma in France: National Registry of Childhood Leukemia and Lymphoma, 1990–1999. Eur. J. Cancer Prev. 2004;13: 97–103.

Committee on Medical Aspects of radiation in the Environment. The incidence of childhood cancer around nuclear installations in Great Britain. Comare 10th report. Chairman: Pr BA Bridges. United Kingdom, London: Health Protection Agency, 2005. ISBN:0-85951-561-563.

A.S. Evrard, D. Hémon, A. Morin, D. Laurier, M. Tirmarche, J.C. Backe, M. Chartier, J. Clavel. Childhood Leukaemia Incidence around French Nuclear Installations using a Geographic Zoning based on Gaseous Release Dose Estimates. Br. J. Cancer 2006; 94: 1342-1347.

Groupe Radioécologie Nord-Cotentin. Volume 4 : Estimation des doses et des risques de leucémies associés. Fontenay-aux-Roses, France : Institut de protection et de sûreté nucléaire, juillet 1999.

A.V. Guizard, O. Boutou, D. Pottier, X. Troussard, D. Pheby, G. Launoy, R. Slama, A. Spira, ARKM (Registre des cancers de La Manche). The incidence of childhood leukaemia around the La Hague nuclear waste reprocessing plant (France): a survey for the years 1978-1998. J. Epidemiol Community Health. 2001; 55: 469-474.

J.M. Hattchouel, A. Laplanche, C. Hill. Leukaemia mortality around French nuclear sites. Br. J. Cancer 1995; 71: 651-653.

D. Laurier, D. Bard. Epidemiologic studies of leukemia among persons under 25 years old living near nuclear sites. Epidemiol Rev. 1999; 21: 188-206.

D. Laurier, J. Clavel, M. Chartier, E. Jougla, M. Tirmarche, S. Billon, S. Caer, J.P. Gambard, D. Hémon, A.S. Evrard, M. Koning, A. Goubin, S. Bellec, A. Morin, J. Brenot, J.C. Backe, E. Michel. Exposition environnementale aux rayonnements ionisants et risque de leucémie chez les enfants. Rapport scientifique final dans le cadre du Programme Environnement-Santé 1999, Contrat N° AC014E. Paris, France : ministère de l’Ecologie et du Développement durable, mai 2003.

D. Laurier, B. Grosche, P. Hall. Risk of Childhood Leukaemia in the Vicinity of Nuclear Installations: Findings and Recent Controversies. Acta Oncol. 2002; 41: 14-24.

D. Laurier, C. Rommens, C. Drombry-Ringeard, A. Merle-Szeremeta, J.P. Degrange. Evaluation du risque de leucémie radio-induite à proximité d’installations nucléaires : l’étude radioécologique Nord-Cotentin. Rev. Epidémiol Santé Publique 2000; 48: 2S24-36.

A. Morin, J.C. Backe. Programme Environnement et Santé 1999. Une estimation de l’exposition du public due aux rejets radioactifs des centrales nucléaires. IRSN, Note technique SEGR/SAER/02-51 Indice 1. Institut de radioprotection et de sûreté nucléaire, Fontenay-aux-Roses, juillet 2002.

A. Morin, J.C. Backe. Programme Environnement et Santé 1999. Une estimation de l’exposition du public due aux rejets radioactifs des sites nucléaires de Cadarache, Saclay, Romans-sur-Isère et Pierrelatte. IRSN, Note technique SER/UETP/03-73 Indice 1. Institut de radioprotection et de sûreté nucléaire, Fontenay-aux-Roses, décembre 2003.

C. Rommens, D. Laurier, A. Sugier. Methodology and Results of the Nord-Cotentin Radioecological Study. J. Radiol Prot. 2000; 20: 361-380.

C. Rommens, A. Morin, A. Merle-Szeremeta. Le modèle Focon d’évaluation de l’impact dosimétrique des rejets radioactifs atmosphériques des installations nucléaires en fonctionnement normal. Radioprotection 1999 ; 34: 195-209.

J.F. Viel, D. Pobel, A. Carre. Incidence of leukaemia in young people around the La Hague nuclear waste reprocessing plant: a sensitivity analysis. Stat. Med. 1995; 14: 2459-2472.

M. White-Koning, D. Hémon, D. Laurier, M. Tirmarche, E. Jougla, A. Goubin, C. Clavel. Incidence of childhood leukaemia in the vicinity of nuclear sites in France, 1990-1998. Br. J. Cancer 2004; 91: 916-922.

M. White-Koning, D. Hémon, D. Laurier, M. Tirmarche, E. Jougla, A. Goubin, C. Clavel. Incidence des leucémies de l’enfant aux alentours des sites nucléaires français entre 1990 et 1998. Bulletin épidémiologique hebdomadaire 2006 ; 4: 31-32.


The ENVIRHOM research program is aimed at gathering new sci-

entific data on the effects of chronic internal exposure to radionu-

clides through experimentation on living organisms (rodents,

microalgae, fish, etc.), with particular emphasis on the impact on

major physiological functions such as breathing, reproduction,

digestion or behavior. The first part of the program set out to

determine whether the transfer or toxicity data obtained for acute

exposure to radionuclides, and on which radiation protection mod-

els have been based, could be transposed to chronic exposure situ-

ations. Uranium was the first radioelement to be studied as it occurs

naturally at quite significant concentrations in some regions (Finland,

New Mexico, and Canada for example) and can also be found as a

result of human activity (uranium mines and reprocessing plants,

depleted uranium used in recent conflicts).

The first phase of the ENVIRHOM project (2003-2006) contrib-

uted new knowledge for assessing the health and environmental

risks associated with chronic exposure to trace concentrations of

radionuclides.

In the "human health" part of the program, IRSN developed a

rat model for chronic ingestion of low quantities of radionuclides

contained in drinking water over a period of several months. A

single, common model for all the experiments was used to make

a cross-comparison of studies on biokinetics, bioaccumulation

and effects on many physiological functions (Figure 1). The

results from this model following exposure to uranium were

unexpected in terms of targets (brain, liver) and biological effects

on numerous physiological functions. In particular, it was dem-

onstrated that uranium, when ingested chronically at doses close

to the maximum levels found in the environment, induced effects

on several types of metabolism: metabolism of drugs [Gueguen

et al., 2007], vitamin D [Tissandié et al., 2007], iron [Donnadieu-

Claraz et al., 2007], and neurotransmitters [Bussy et al., 2006].

Effects on animal behavior were also observed [Lestaevel et al.,

2005] and [Houpert et al., 2005]. These functional, cellular and

molecular changes do not seem to lead to pathologies in labo-

ratory animals.

In the "environmental" part of the program, early changes in

functions such as breathing, behavior or feeding were observed

at low exposure levels. Effects were also observed on the repro-

ductive function, but at a later stage.

Isabelle Dublineau, Philippe Lestaevel, Yann Gueguen, Maâmar Souidi and François PaquetExperimental Radiotoxicology Laboratory

The impact of chronic internal low-dose contamination on human health and ecosystems remains an open ques-

tion, as not enough is known about the effects of this type of exposure. Some disputed studies have reported

numerous pathologies (leukemia incidence around the Sellafield site, various diseases in children exposed

to contamination from the Chernobyl accident, cancer incidence after nuclear tests, Gulf war syndrome, etc.)

which, according to certain authors, may be related to such exposure. At the same time, public concern about

the preservation and restoration of the environment has grown considerably.

The eNVIRhoM PRogRaM: new knowledge in the field of human radiation protection

3. 3


3. 3

first uranium, then cesium

The results obtained by IRSN in its efforts to learn more about

the effects of uranium have shown that the model can be used

to advantage in the laboratory to study the effects of chronic

ingestion of radionuclides at low doses. The model was therefore

extended to study the effects of cesium-137, a radionuclide

dispersed in the wake of the Chernobyl accident and incorpo-

rated into the food chain. The studies considered a dose equivalent

to a post-accident dose of 6,500 Bq/l, which represents the inges-

tion of 150 Bq per day. The first objective of these experiments

was to determine whether the functions modified by uranium

were also sensitive to chronic ingestion of cesium-137, i.e. wake/

sleep cycle, spatial memory, cholesterol metabolism, vitamin D

metabolism, and secretory capacities of the intestine and cardio-

vascular system. The results of these studies were published or

submitted to international scientific journals in 2006 and 2007

[Dublineau et al., 2007, Houpert et al., 2007, Lestaevel et al., 2006,

Souidi et al., 2006, Tissandié et al., 2006, Guéguen et al., 2008].

accumulation of 137cs after chronic ingestion in main target tissues

An initial study of the biokinetics of cesium-137 after several

months of contamination (1, 3 and 9 months) was carried out

to identify the main target tissues where the radionuclide accu-

mulates after chronic ingestion. The results obtained after inges-

tion of cesium-137 for three months are shown in Figure 2. The

mean accumulation rate in the different tissues is approxi-

mately 5 Bq/g. However, more significant accumulation can be

observed in three organs: the thyroid, skeletal muscle (thigh

muscle) and the pancreas. Unlike uranium, very little cesium

accumulates in the bones (femur). The absence of cesium in the

gastrointestinal tract and blood is explained by its rapid tis-

sular absorption and distribution.

Alongside this biokinetic study, IRSN's Internal Dosimetry Division

is investigating the tissular distribution of cesium-137 by SIMS

(Secondary Ion Mass Spectroscopy) (analyses currently in prog-

ress).

Bq/g

0

5

10

15

20

25

0He

art

Thyr

oid

Fem

ur

Thigh

mus

cle

Splee

n

Panc

reas

Gastr

ointe

stina

l tra

ct

Liver

Kidn

eys

Bloo

dAo

rta

Adre

nal g

land

Brain

Adrenal gland

Kidneys

Femur

Muscle

Liver GIT

Spleen

Pancreas

Thyroid

Heart

Aorta

Brain

Blood

Biokinetics, bioaccumulation

MetabolismsVitamin D, medication, iron,

cholesterol, steroid hormones

Central nervous systemNeuroinflammation,

oxidative stress, behavior, anxiety, memory, sleep

PhysiologyCardiovascular and digestive

systems

ImunitySystemic, mucosal

Rats contaminated via drinking water supplied ad libitum at environmental doses, for periods ranging from a few days to several months

Figure 1 Model of chronic ingestion of radionuclides.

Figure 2 Accumulation of 137Cs in rats after ingestion for 3 months.



3. 3

sleep cycles in contaminated rats (Figure 4). The increase in the

number of waking and slow-wave sleep episodes, observed after

one month of contamination, is offset by the decrease in the

mean duration of these episodes. Interestingly, spectral analysis

of the electroencephalogram showed an increase in the

0.5-4 Hz band in animals given cesium-137 doses for three

months, a phenomenon also observed in children born in Ukraine

after the accident.

This data indicates that the effects of cesium-137 are different

from those induced by uranium and suggests that the central

nervous system is not a target for cesium-137 after ingestion

at post-accident doses in rats.

steroid metabolisms: cholesterol and vitamin d

It has recently been suggested that cesium-137 contamination

may have biological effects on the development of non-cancer-

ous diseases such as cardiovascular diseases and lipid disorders.

It was therefore important to study the impact of chronic

cesium-137 contamination on cholesterol metabolism. The

results show that cholesterol, triglyceride and phospholipid

plasma levels are unaffected by chronic ingestion of cesium-137

at post-accident doses. Molecular-scale variations in proteins

involved in cholesterol metabolism are, however, observed in

the liver, together with an increase in the enzymatic activity of

The central nervous system is not a target for 137cs in post-accident doses

Several disturbances associated with the central nervous system

(behavioral disorders, anxiety, depression, lack of attention) have

been observed in certain exposed populations following the

Chernobyl accident. Electroencephalogram variations associated

with decreases in IQ scores have also been observed in children

born within months following the accident. However, it is dif-

ficult to determine the real causes of these disturbances and

the extent to which various factors may be responsible for

cognitive disorders: psychological stress following the accident

and its effects, external irradiation of the body as a whole and

the brain in particular at the time of the accident, or internal

contamination due to chronic ingestion of contaminated foods

by populations living in contaminated areas. The lack of relevant

studies on the effects of cesium-137 on the central nervous

system at low doses led IRSN to study the effects in rats of

chronic contamination over a period of several months at post-

accident doses.

Behavior tests, including locomotion, object recognition, spatial

memory and forced swimming tests, were conducted on rats

contaminated for three, six and nine months. The results obtained

show that, at the doses ingested, cesium-137 induces no chang-

es in behavioral tests as compared to uncontaminated animals

of the same age (Figure 3).

Similarly, the electroencephalogram analyses showed no chang-

es in the total duration of the waking, slow-wave sleep and REM

50

55

60

65

70

75Alternation %

Y-maze

Contamination time (months)630 9

137CsControl specimens

Figure 3 Effects of 137Cs on spatial memory.


3. 3

Duration (minutes)

0

50

100

150

0 30 90

REM sleepDuration (minutes) Slow-wave sleep

0

200

400

600

800

1000

0 30 90

Duration (minutes)

Electroencephalogram (EEG): Measurement of electrical brain activity

Waking

0

200

400

600

800

0 30 90

Waking

REM sleepBrain waves


Contamination time (days)

Slow-wave sleep

Figure 4 Effects of 137Cs on the sleep-wake cycle.

Figure 5 Effects of 137Cs on cholesterol metabolism.

CYP7A1 CYP27A1

0

5

10

15

20

25

CYP activity(pmol/mn/mg prot)

CYP7A1 CYP27A1

Enzymatic activity of cytochromes P450 in the liver after contamination with

cesium-137 for three months

BILE ACIDS

BILE

CHOL

CHOL

ABC A1

SRB1

HDL

LDL-r

LDL

ABC G5

HMGCoA (R,S)

CYP51

LXRα, PPAR α, γ LXRα, PPAR α, γFXRRXR

LXRα, PPAR α, γ

*



3. 3

Intestinal functions

As with the physiological functions mentioned earlier, very few

studies describe the effects of chronic ingestion of cesium-137

on the digestive tract, even though it is the first biological

system exposed to radionuclides in case of ingestion. This is all

the more paradoxical given its extreme sensitivity to ionizing

radiation. A study was therefore conducted to determine the

effects of cesium-137 contamination through the ingestion of

post-accident doses (150 Bq/day) for a period of three months

in rats. Few effects were observed on the intestine in terms of

histopathology (morphology), inflammatory status and secre-

tory capacity, apart from a decrease in apoptosis (programmed

cell death) in the intestinal wall (Figure 7), possibly reflecting

an adaptive response of the tissue. New experiments are required

to estimate the consequences of this decrease in spontaneous

apoptosis.

a cytochrome P450 called CYP27A1, which helps to transform

cholesterol into bile acids (Figure 5).

In conclusion, chronic ingestion of cesium-137 at post-accident

doses induces subtle molecular changes in the liver, but with no

effect on plasma profile over the time period considered. A

longer contamination period (e.g. 9 months) would probably be

necessary to induce a lipid disorder.

Of the different pathologies observed in populations exposed

to cesium-137 after the Chernobyl accident, bone problems with

changes to mineralization resulting in osteoporosis have been

reported. Studies of vitamin D metabolism, including an analy-

sis of hormone profiles (various forms of vitamin D and PTH)

and phosphocalcic profiles, were conducted alongside tissue

measurements (kidney, liver and brain) of the cytochromes P450

involved in vitamin D metabolism, its nuclear receptors and its

target genes. Figure 6 shows that chronic ingestion of cesium-137

reduces the plasma rate of active vitamin D3. Molecular modi-

fications are also observed in the tissues, indicating that vitamin

D metabolism is a biological target in cases of chronic ingestion

of cesium-137.

Figure 6 Effects of 137Cs on vitamin D metabolism.

KIDNEY

LIVER

SKIN

1α 25 (OH)2D3Active form

Calcium

Phosphate

Pre-vitamin D25 (OH)D3

Vitamin D3

Vitamin D3 (cholecalciferol)

Pre-vitamin D3

7-dehydrocholesterolUVB

Food

Hormonal and ionic profile in the plasma after 3 months of 137 Cs contamination

H)DOH25 (O 33l)ol/(pmo)( 102.1 9,9 + - 98.0 7.5 + -

1α )H)O5( 25 2D33l)ol/(nmo

( 92.4 17.1 + - 44.0 7* + -

PTH)ml)(pg/m

142.6 15.8 + -

mumCalcil)ol/l(nmo

tehatphPhosp/l)ol/(mmo

pp

156.4 12.2 + -

2.71 0.03 + - 2.71 0.06 + -

1.44 0.07 + - 1.48 0.05 + -

Control (n=10) 137Cs (n=10)


3. 3

In order to analyze whether disturbances to this system are due

to the absorption of cesium-137 through the food chain, various

studies were conducted using our model of chronic cesium-137

contamination at post-accident doses. An initial study con-

ducted on rats contaminated for three months provided a few

cardiovascular system

The literature has described alterations of the cardiovascular

system in liquidators or in children living in contaminated areas

following the Chernobyl accident.

0

20

40

60

80

100

120

140Number of villi

Apoptotic cells per villusIntestinal villi: apoptotic cells shown in brown

230 3 4 5


* *

-0,8

-0,4

0

0,4

0,8

1,2

1,4

0,1 0,2 0,3 0,4 0,5

-0,8

-0,4

0

0,4

0,8

1,2

1,4

0,1 0,2 0,3 0,4 0,5Seconds

mV

mV

Seconds

Electrocardiogram (ECG)

137Cs

+52%CK, CK-MB

=Ions (CI, K, Na)

+130%Potassium channels

-0,8

-0,4

0

0,4

0,8

1,2

1,2

1,2

Time (hours)

Control

137Cs

Mean arterial pressure (mm Hg)

20:0

0

23:0

0

02:0

0

05:0

0

08:0

0

11:0

0

14:0

0

17:3

0

20:0

0

23:0

0

02:0

0

05:0

0

08:0

0

11:0

0

14:0

0

17:3

0

20:0

0

Figure 7 137Cs and programmed cell death (apoptosis) in the intestine.

Figure 8 Effects of 137Cs on the cardiovascular system.



3. 3

future activities in the eNVIRhoM program: Beginning of Phase 2

All the data acquired during the first phase of the ENVIRHOM

program (from 2003 to 2006) justifies the need for IRSN to take

this research work into chronic risks further still.

The initial feasibility demonstration phase was based on a broad

screening of the effects of uranium on various physiological

functions and tissues. In particular, the preferential targets of

uranium were determined. In its second phase, the ENVIRHOM

program will define itself more clearly as an experimental research

program, focusing on the preferential targets of uranium effects.

Moreover, in order to reinforce the cross-disciplinary aspect of

the program, several studies relating both to the environment

and human health will be started up. In particular, this will include

work on the reproductive system, development and behavior.

The research program will follow two main lines of development.

Firstly, it will set out to assess the physiological responses of

uranium targets as a function of exposure levels, for example,

by determining the No Observed Adverse Effect Level (NOAEL).

At the same time, it will seek to determine and improve under-

standing of the action mechanisms behind the effects observed

in the presence of uranium. In the "human health" part of the

program, the respective roles of the radiological and chemical

properties of uranium will be analyzed further, along with trans-

port and defense mechanisms in target tissues.

answers: modifications to plasma markers of cardiac damage

(CK, CK-MB), changes in the expression of potassium channels

(Kir-6 and SUR) and of proteins involved in vascular tone (ACE,

BNP) and decrease in arterial pressure (associated with its loss

of circadian rhythm), while no tissue damage was observed and

ECG curves were normal (Figure 8). These studies will be backed

up by longer-term and/or earlier contamination protocols,

together with more sensitive models (growing organisms, animals

prone to certain pathologies).

effects of cesium-137 on the organism at post-accident doses: conclusion

These studies all show that chronic contamination through

ingestion of cesium-137 at post-accident doses for three months

has little effect on the main physiological functions tested

(central nervous system, intestinal and cardiovascular functions

and metabolisms), contrary to observations made after chronic

ingestion of uranium. Nevertheless, longer term studies (nine

months) on more sensitive models are planned in order to

confirm that daily ingestion of cesium-137 in doses equivalent

to those received by populations living in contaminated areas

has no effects.

References

I. Dublineau, S. Grison, L. Grandcolas, C. Baudelin, F. Paquet, P. Voisin, J. Aigueperse et P. Gourmelon, 2007, Effects of chronic 137Cs ingestion on barrier properties of jejunal epithelium in rats. J Toxicol Environ Health 70, 1-10.

Y. Guéguen, P. Lestaevel, L. Grandcolas, C. Baudelin, S. Grison, J.-R. Jourdain, P. Gourmelon et M. Souidi, 2008, Chronic contamination with 137Cesium radionuclide in rat: impact on cardiovascular system. Cardiovascul. Toxicol. 8, 33-40.

P. Houpert, J.C. Bizot, C. Bussy, B. Dhieux, P. Lestaevel, P. Gourmelon, F. Paquet, 2007, Comparison of the effects of enriched uranium and 137-cesium on the behaviour of rats after chronic exposure. Int J Radiat Biol 83, 99-104.

P. Lestaevel, B. Dhieux, E. Tourlonias, P. Houpert, F. Paquet, P. Voisin, J. Aigueperse, P. Gourmelon, 2006, Evaluation of the effect of chronic exposure to 137 cesium on sleep-wake cycle in rats. Toxicology 226, 118-125.

M. Souidi, E. Tissandie, L. Grandcolas, S. Grison, F. Paquet, P. Voisin, J. Aigueperse, P. Gourmelon, Y. Gueguen, 2006, Chronic Contamination with 137Cesium in Rat: Effect on Liver Cholesterol Metabolism. Int J Toxicol 25, 493-497, 2008.

E. Tissandie, Y. Gueguen, J.M. Lobaccaro, J. Aigueperse, P. Gourmelon, F. Paquet, M. Souidi, 2006, Chronic contamination with 137Cesium affects Vitamin D3 metabolism in rats. Toxicology 225, 75-80.


Biological dosimetry

The population triage method used by the Biological Dosimetry

Laboratory (LDB) consists in counting radiation-induced chromo-

some aberrations in the lymphocytes of the circulating blood (by

means of a simple blood sample). The radiation-specific chromo-

some aberrations sought are dicentric and centric ring chromosome

aberrations (Figure 1). Their frequency is very low in non-irradiat-

ed cells (approximately 1 out of every 1000 cells analyzed), and

increases with the dose received by the victim. These chromosome

aberrations therefore make excellent biomarkers for estimating

exposure to ionizing radiation [L. Roy, 2006].

The potential dose received by the victim is determined by plotting

Isabelle Clairand, François TrompierIonizing Radiation Dosimetry Laboratory

Laurence Roy, Eric GrégoireBiological Dosimetry Laboratory

When managing crisis situations brought about by radiological accidents involving a potentially high number of

victims, it is crucial to identify as quickly as possible the most severely exposed individuals requiring immediate

medical care. Population triage based on clinical signs may be implemented, although these signs often vary

significantly from one person to another. New triage methods based on biological and physical dosimetry are

being developed for external irradiation situations to back up the observation of clinical signs. Given the variety

of exposure situations and the fact that no single method can address all situations, the combined use of different

techniques should improve the accuracy and efficiency of the triage process [G. Alexander, 2006]. In order to

obtain a rapid and sensitive response, IRSN's Biological Dosimetry Laboratory (LDB) and Ionizing Radiation

Dosimetry Laboratory (LDRI) are currently developing population triage methods combining biological and

physical dosimetry.

TRIage of exPosed PoPulaTIoNs

3. 4

Figure 1 Metaphase chromosomes of lymphocytes irradiated at 5 Gy (60 Co, 0.5 Gy/min).



3. 4

the frequency of specific anomalies against a reference calibration

curve prepared in the laboratory. Such curves have been prepared

by IRSN for various types of radiation.

The dakar accident: a full-scale test

The accident

In 2006, the biodosimetry triage method for potentially exposed

populations was tested in real conditions. On June 3, 2006, after

taking a gamma-ray image on a worksite in Dakar (Senegal), an

iridium-192 source came loose from its guide tube and remained

trapped in the ejection duct. The duct and tube were then stored

in an office until July 31, 2006, when the equipment was sent by

express mail to Abidjan (Ivory Coast). The first time he tried to use

the gamma radiography unit in Abidjan, the operator discovered

the loose iridium source.

It was believed that 63 persons might have been irradiated as a

result. These persons had all been in close contact with the source

(while it was in storage, when preparing and handling the shipping

package in Dakar, or while attempting to use the equipment in

Abidjan). Four of these people presented localized radiation-induced

lesions and were taken to the Percy Military Hospital (Clamart,

France). Of the remaining 59 persons, 50 were from Dakar and nine

from Abidjan. The Biological Dosimetry Laboratory was asked to

make a biodosimetric assessment of the dose received by the 59

potentially irradiated persons to determine the most appropriate

medical care.

biodosimetry triage

The triage of patients relies essentially on a rapid, initial dosimetric

assessment based on a simple blood sample. Since lymphocyte

culture time (48 h) cannot be reduced, the process can only be

accelerated during the chromosome aberration counting phase.

Therefore, only 50 cells per patient are analyzed at first to sort the

victims according to exposure level. This initial estimate yields

results for a patient in one hour, although it is only accurate to

within 1 Gy.

Despite the large number of blood samples to be analyzed, IRSN

handled the crisis successfully, providing exposure level results

within an extremely short time. In all, it took less than 5 days to

analyze 50 cells in the 59 samples.

Table 1 shows the results obtained after triage of potentially exposed

individuals. As a result of this rapid triage, based on the analysis of

50 cells, 46 persons were found to have no chromosome aberrations,

11 persons had one aberration, and two others two aberrations.

The biodosimetric analysis rapidly confirmed that the victims had

received a dose of less than 1 Gy.

Although this triage phase provided a rough estimate of the dose

received by exposed individuals, measurements were not accurate

enough to determine the long-term medical needs of the victims.

To overcome this handicap, the number of cells analyzed was

increased to reduce the sensitivity of the method from 1 to 0.2 Gy.

The analysis of 500 cells confirmed that 30 individuals had no

chromosome aberrations. A positive dose (though not signifi-

cantly different from zero) was detected in 24 persons. Five persons

were identified as significantly exposed. The highest dose measured

was 0.4 Gy.

The analysis of several hundred cells led to a new dose-related

classification of individuals that was more accurate than that based

Figure 2 Dose-effect curves as a function of irradiation source.

Table 1 Triage results following the Dakar accident as a function of the number of chromosome aberrations observed in 50 cells

Frequency of dicentricand centric rings

Cobalt-60 curve, 0.5 Gy/min

Cobalt-60 curve, 0.1 Gy/minNeutron curve

X-ray curve, 0.1 Gy/min

Dose (Gy)0 1 2 3 4 5

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

class 0(0 aberrations)

class 1(1 aberration)

class 2(1 aberration)

Number of individ-uals in each class, based on the observation of 50 cells

46 11 2

Mean dose [95% confidence interval]

0.35 Gy [0-1.28] 0.59 [0.02-1.49]

Class 0: no aberrations observed, zero dose; Class 1: positive dose, but zero dose within the confidence interval; Class 2: significantly positive dose.


3. 4

obtain simultaneous measurements of the expression level of about

25,000 genes in the lymphocytes of each potentially irradiated

individual.

Analysis of these expression levels led to the identification of a

subgroup of 22 genes in which the expression profiles were used

to distinguish between unexposed and exposed individuals, regard-

less of dose level. Dose-specific expression profiles could not be

identified (Figure 4). Additional studies are currently in progress to

confirm these initial results.

experience feedback from the dakar accident

The Dakar accident is one of the most serious in recent years in

terms of the number of persons potentially concerned. It provided

a unique framework for testing new methods for the triage of

populations exposed to ionizing radiation.

Apart from the very lengthy reference method, the other three

approaches (50-cell analysis, automatic detection, oligonucleotide

chips) require identical treatment and analysis times. Based on the

various comparisons made, the 50-cell analysis method produces the

highest percentage of false negative results. The automatic dicentric

detection method leads to an overestimation of doses, but is never-

theless efficient for discriminating between high and low doses. The

oligonucleotide chip method is very sensitive and can distinguish

individuals with low exposure from those who are not exposed at all.

This saves a significant amount of time as it eliminates the need for

lymphocyte culture. In addition, given the population triage consid-

ered (with the maximum dose not exceeding 1 Gy), it is difficult to

determine how efficient the method is in identifying highly exposed

individuals. Further studies need to be conducted on this aspect.

on the analysis of 50 cells. In order to estimate the error produced

during the initial triage phase, the results obtained from the analy-

sis of 50 cells were compared with those obtained after more

accurate dose assessment. This comparison shows that the rapid

triage method allows correct classification of 69% of individuals.

However, the percentage of false negative results remains significant

with this method.

Overall, the triage method based on the analysis of 50 cells led to

an underestimation of the dose in some 30% of cases, but never

an overestimation.

new approaches to improve triage

Given the high rate of error and poor accuracy of the rapid triage

method, new experimental approaches have been tested to improve

the triage of populations potentially exposed to ionizing radiation.

These approaches have been developed through research programs

conducted by the Biological Dosimetry Laboratory and consist

mainly in the use of an image analysis system to detect dicentric

aberrations automatically and the use of oligonucleotide chips.

Automatic dicentric detection systems have been developed sporadi-

cally by various research teams, but have not been used for the pur-

poses of population triage. Given the dose underestimates associated

with the population triage method, it seemed necessary to test this

approach once again using the only off-the-shelf software available:

Metasystems Metafer 4.

For the Dakar accident, automatic dicentric detection was carried

out on 46 of the 59 individuals from all three exposure classes.

Figure 3 shows that in terms of efficiency, the automatic dicentric

detection method is between the reference method (observation

of 500 cells) and rapid triage method (50 cells).

The other technique studied (use of oligonucleotide chips) aims to

increase both the rapidity and sensitivity of results. Several studies

show that the expression of certain genes can be specifically

modulated according to radiation dose. The chips were used to

%

Zero dose Insignificant positive dose

Positive dose0

10

20

30

40

50

60

70

80

50 cells500 cells

Automatic detection

number of individuals in each class

class 0(0 aberrations)

class 1(1-4 aberrations)

class 2(more than 4 aberrations)

Afterobservationof 500 cells

30 24 5

Class 0: no aberrations observed, zero dose; Class 1: positive dose, but zero dose within the confidence interval; Class 2: significantly positive dose.

Table 2 Triage results following the Dakar accident as a function of the number of chromosome aberrations observed in 500 cells.

Figure 3 Distribution of individuals as a function of exposure level for the three methods used.



3. 4

in the phaners and of sodium in the blood for several decades to

estimate neutron doses. For triage purposes, several methods are in

use at IRSN, including phaner or blood sample measurements, whole

body counts, and, more simply, radiation measurement of the dose

rate due to sodium activation in the umbilical region of exposed

individuals.

With the exception of neutron activation techniques (for which

triage aspects have already been studied and operational capabili-

ties regularly tested), retrospective dosimetry techniques such as

EPR and OSL are not directly transposable to emergency situations

involving a large number of victims, and requiring specific investi-

gation to guarantee effective use. In such emergency situations,

requirements in terms of measurement capacity, response time and

measurable materials are different from those encountered in

general accident situations where the number of victims is small.

Due to the invasive nature of the sampling process, the use of EPR

measurements of tooth enamel or bone tissue samples cannot be

considered for this type of application. In emergency situations, the

durability of dosimetric data is no longer a valid criterion. In such

situations, samples would probably be taken from victims shortly

after irradiation. Most importantly, the invasive nature of the

sampling method used on the materials to be analyzed must be

minimized. These materials must be found in the majority of exposed

individuals, and their dose detection limits must be compatible

with population triage requirements.

Materials such as phaners, plastic and glass may be used in spite

of the significant loss in the measured EPR signal as time since

irradiation elapses. Recent studies have shown that OSL techniques

can also be used for accident dosimetry. An OSL reader has been

physical dosimetry

The physical dosimetry methods developed for triage purposes in cases

of external irradiation are based on electron paramagnetic resonance

spectrometry (EPR), optically stimulated luminescence (OSL) and

activation techniques, in the specific case of neutron irradiation.

At IRSN, the EPR method is mainly used in conjunction with biodosim-

etry and numerical or experimental reconstruction methods to estimate

doses received by radiation accident victims, as in the case of the

accidents in Bialystok (Poland, 2001), Lia (Georgia, 2003), Chile (2005)

and Dakar-Abidjan (Senegal and Ivory Coast, 2006 [Clairand et al., 2006

and 2007; Huet et al. 2007a and b; F. Trompier et al., 2007a]. Doses are

often estimated several weeks or even months after irradiation. EPR

measurements of bone tissue or tooth enamel biopsies are used to

estimate received doses, as these materials are rare in that they preserve

dosimetric data for several years. This method is particularly useful when

dealing with members of the general public, who, of course, do not

undergo any dosimetric monitoring, and in specific cases of localized

or highly heterogeneous irradiation.

OSL techniques are not usually employed in the context of accident

dosimetry, although they are used to reconstruct doses in cases of

chronic exposure, such as in contaminated areas of the former Soviet

Union. Several European and Russian teams use OSL measurements

on construction materials to estimate accumulated doses following

site contamination. These data can then be used to reconstruct the

doses to which local populations have been exposed.

At IRSN, activation techniques are mainly used for criticality accident

dosimetry. French medical analysis laboratories - and IRSN in par-

ticular - have been using routine measurements of activated sulfur

Figure 4 Gene expression levels as a function of exposure class.

Relative expression level (a.u.)16

–4

–2

0

2

4

8Non-exposed individuals Exposed individuals

Class 1 and 2 victimsClass 0 victims

06 2

9

06 3

2

06 4

6

06 5

3

06 5

6

06 6

0

06 6

2

06 6

4

06 7

3

06 7

5

06 2

6

06 6

3

06 7

1

06 7

2

06 8

1

06 4

4

06 4

5

06 7

0

06 7

6

06 8

2


3. 4

impact of external parameters in terms of irradiation, storage and

measurement (temperature, humidity, light).

Initial results show that for mobile phone screen protection made

from PMMA, CR-39 eyeglass lenses, glass used in making LCD screens

and wrist watches, and fingernail samples, detection limits in the

region of 1 or 2 Gy can be achieved for measurement times of

approximately 5 minutes [Trompier et al., 2007b]. It takes a few

people and ionizing radiation - accueil - irsn...irradiation dose. these are necrotic and...

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