Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

LUNG CANCER RISK ATTRIBUTABLE TO INDOOR RADON IN A HIGH
RADON POTENTIAL REGION OF FRANCE
O. Catelinoisa, F. Clinardb, K. Auryb-c, P. Pirarda, L. Nouryd, A. Hocharde, C. Tillierb
a

Institut de Veille Sanitaire - Saint Maurice
Cire Centre-Est - Dijon
c
Centre d’Epidémiologie de Population - Registre dijonnais des AVC - Dijon
d
Direction Régionale des Affaires Sanitaires et Sociales de Franche-Comté - Besançon
e
Observatoire Régional de la Santé de Franche-Comté - Besançon
b

Abstract
Awareness of the health risks due to exposure to indoor radon has raised concern about its impact in
the general population. Using all available epidemiologic results, our goal is to accurately estimate
this risk based on data collected in a high radon potential region of France (Franche-Comté). For
this study, we considered exposure (response relations derived from cohorts of miners and from
joint analyses of residential case) from various control studies. The exposure data come from a
representative measurement campaign conducted in Franche-Comté. The estimated number of lung
cancer deaths attributable to indoor radon exposure in this region ranges from 72 to 139, depending
on the model considered. The attributable risk is higher in granitic area (22 to 39% for 7 to 12
deaths) but the number of deaths is higher in sedimentary area (65 to 127 deaths for 13 to 26%).
Although indoor radon concentrations are higher in granitic area, the public health impact is more
important in sedimentary area because of higher population density.

Introduction
The French National Institute of Heath Survey (InVS) recently estimated that 1,000 to 3,000 lung
cancer deaths a year may be attributable to radon exposure (Catelinois et al., 2007). In the regions
where radon is a potential issue, an accurate assessment of its health impact is important to inform,
to sensitize the population and to target actions of risk prevention.
According to the French National Radon Measurement Campaign performed between 1984 and
1999, Franche-Comté is a French region particularly concerned with radon. But this nation-wide
designed study, relying on measurements realized in volunteers’ houses, may not be the best way to
assess with accuracy the number of cancer deaths attributable to radon exposure. In fact, the
National Campaign was designed to ensure a homogeneous geographic distribution of the
measurements (the country was divided into grids of 40 km2) with at least one measurement per
grid. Grids that included municipalities with more than 1,500 inhabitants had a second
measurement taken in a different location. Volunteers were mainly recruited through contacts in
the local governments, which placed and collected the radon detectors. Therefore, data collected in
Franche-Comté during this period were not very numerous and perhaps not representative of the
various housing types. A more specific design developed for Franche-Comté could be more
efficient to assess indoor radon exposure in the region.

Objective
The first goal of this study was to assess the lung cancer death risk due to indoor radon exposure in
Franche-Comté, using a specific radon exposure assessment. A secondary objective was to
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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

compare the results of this assessment with those obtained using the French National Radon
Measurement Campaign already available for all French regions.

Subjects and methods
Study setting

Franche-Comté is a mountainous region situated in NE France bordered to the East by Switzerland.
The 16,202 Km² region has three towns which concentrated 50% of the population in 28% of the
surface area with half of the region being wooded. Franche-Comté is divided in 4 administrative
areas (departments): Doubs, Jura, Haute-Saône and Territoire de Belfort.
Identification of the population

According to the 1999 French National Institute of Statistics and Economics (INSEE, 2000) census,
the total Franche-Comté population consisted of 1,117,257 people. The sex ratio was close to 1 ;
25% were younger than 20 years, 54% were 20–59 years, 14% were 60–74 years, and 7% were
older than 75 years. Of this population, according to the French Institute of Health and Medical
Research (INSERM; Paris, France), 512 people died of lung cancer (437 men and 75 women) in
1999.
Radon exposure assessment
Sample scheme

The study aimed to be based on a representative sampling of dwellings of the Franche-Comté
region. This was achieve through the database of the French National Telecommunications
Operator (France-Telecom) which allowed access to the address of most of the population for
constructing the sampling frame (Until 2002, France-Telecom was the only operator in charge of
dwelling connections to the telecommunication network in France). The designated sample size
was 452 dwellings, equivalent to 1 detector per 1,000 homes. The sample was stratified by the
geological structure (defined for each of the 1,786 districts of Franche-Comté according to
geological maps – Genay, 2005) and by the type of housing (detached houses or blocks of flats).
The distribution of the 452 dwellings selected is shown in Figure 1
Questionnaire development and interviewing procedures

Questionnaires were developed by the France-Comté Study staff using the experiences of the
National Radon Measurement Campaign (IRSN, 2000) and the French Indoor Air Quality
Observatory (OQAI, 2003). Up to 7 attempts were made to obtain an answered call for each
sampled telephone number. Data were collected by 3 trained interviewers during face-to-face
interviews in October and November 2005. Dwelling and household characteristics were collected
using standardized questionnaires. The data provided information about demographic
characteristics, residential and smoking habits, and technical characteristics of the dwelling like
surface area, number of room, building materials and ventilation. Indoor radon measurements were
carried out using 2 Kodalpha LR 115 detectors placed in a randomly selected bedroom and in the
living-room for 2 months.
Statistical analysis

The number of lung cancer deaths due to indoor radon exposure was estimated in a four-stage
process: identification of the population, choice of the exposure-response relations, radon exposure
assessment, and characterization of lung cancer risk. As described above, data on population and
lung cancer deaths were provided respectively by the French National Institute of Statistics and
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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

Economics and the French Institute of Health and Medical Research. Concerning the choice of
exposure-response relations, we used results obtain through two major epidemiologic studies: the
joint analysis of 11 cohorts of miners (BEIR 1999) and the joint analysis of 13 European case–
control studies (Darby et al. 2005). They have been resumed in a recent paper (Catelinois et al.,
2006).
Because, indoor radon measurements vary with season (they are highest in winter and lowest in
summer), corrections for seasonal variation was required for the 2-month measurements in order to
estimate annual exposure. To obtain these seasonal correction factors, the model developed by
Pinel et al. (1995) was applied to the French database of indoor radon measurements.
Application of the exposure–response relations mentioned above necessitates knowledge of the
number of spontaneous deaths from lung cancer (i.e., apart from radon exposure). It was assumed
that most of the 512 lung cancer deaths observed in 1999 were probably due to smoking, with some
attributed to indoor radon alone, while others to the interaction between smoking and indoor radon,
and the remainder to such other risk factors as air pollution and occupational exposure (Darby et al.
2001). To estimate the number of lung cancer deaths attributable to indoor radon exposure, we
applied the data described above to the following formula: Nr, a, d, s = (RRr,a × Na, d, s)/(1 + RRr,a),
where Nr, a, d, s is the number of lung cancer deaths due to indoor radon exposure at age a, in district
d and for sex s. RRr,a is the relative risk for age a, and radon exposure r. Na, d, s is the total number of
lung cancer deaths at age a in district d and for sex s. Calculations were carried out by age, gender,
and administrative areas (departments).

Results
The Franche-Comté radon measurement campaign

A total of 907 households were invited to participate. About 50% of those accepted with minor
differences between strata (54.2% for the granitic dwelling stratum, 49.8% for detached houses and
47.7% for flats established on sedimentary geology). Few variables, both available in the FrancheComté study and in the 1999 National French Census (INSEE, 1999), have been used to search a
possible selection bias. Participants did not differ from the inhabitants of Franche-Comté in term of
age, gender, social and occupational group (data not shown). The dwellings of the participant
households were also comparable to the Franche-Comté dwelling park in term of age of
construction, number of rooms in the dwellings and renter / landlord status of the occupants.
Therefore, a post-stratification strategy, initially considered, was not performed.
Comparison between the National Radon Measurement Campaign and the Franche-Comté Study

Table 1 lists a comparison between Franche-Comté measurements extracted from the National
Radon Measurement Campaign in France and the present Franche-Comté Study. In the former
study, measurements were performed in three different types of room with a majority in the livingroom. Although the place of measurement and the period of measurement differ in the two studies,
distributions of radon concentration were quite similar. Indoor radon measurements were slightly
lower in the Franche-Comté Study: arithmetic means were 138.2 and 134.0 Bq/m3 respectively for
the National Campaign and for the Franche-Comté Study, and geometric means were 88.3 and
79.6 Bq/m3.
Estimates of lung cancer deaths attributable to indoor radon exposure in Franche-Comté

Table 2 shows the estimated number of lung cancer deaths attributable to indoor radon exposure
using 2 datasets of indoor radon measurements (the French National Radon Measurement
Campaign and the Franche-Comté Study) and 3 exposure-response relationships. Depending on the
risk model used, the total number of lung cancer deaths ranged from 72 to 174. The calculations
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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

suggest that of the 512 lung cancer deaths in 1999 in Franche-Comté, 8% to 34% may be attributed
to indoor radon exposure. The model obtain from the joint analysis of the European case-control
studies (Darby, 2005), produced the fewest attributable deaths, the age-duration BEIR VI model the
most. Although the proportion of lung cancer deaths varied from 13% to 26% in sedimentary areas
(vs. 23% to 40% in granitic areas) depending to the risk model, 65 to 127 lung cancer deaths were
expected vs. only 7 to 12 in granitic areas.

Discussion
This is the first study in France providing radon concentration measurements based on a
representative sampling of dwellings. This particular design allowed us to calculate with accuracy
the number of lung cancer deaths attributable to indoor exposure in a high level indoor radon area.
The results indicate that Franche-Comté is a high radon-emission area, even in the sedimentary
zone. Using the risk assessment method proposed by the NRC (Covello and Merkho, 1993 ; NRC,
1983) we estimated the number of lung cancer deaths in France in 1999 attributable to indoor radon
exposure. The consideration of several different exposure-response relations, which come from
either cohorts of miners or residential case-control studies, allowed us to compare estimates of
attributable deaths based on various exposure-response relations. We also considered the variability
of indoor radon exposure between and within sedimentary and granitic areas of Franche-Comté.
Over the past two decades, many epidemiologic studies, mainly cohorts of miners and case–control
studies in the general population, have estimated the lung cancer risk associated with radon
exposure. Because miners are generally exposed to higher levels than the general population, using
miners’ data for assessing risks in general population clearly raises methodological issues,
especially those related to the extrapolation of risk from high to low exposure and the transposition
of risk estimates from miners to the general population (BEIR 1999). Although the radon hazard is
no longer subject to debate, the use of risk models based on occupational exposure to assess the
lung cancer risk attributable to indoor radon exposure is rightfully still considered a problem.
In this risk assessment, the number of lung cancer deaths due to indoor radon exposure is relatively
stables regardless the exposure-response relation used. Nevertheless, as in the risk assessment
performed for the entire of France, risk estimates obtained from miner studies appear conservative.
Lung cancer deaths due to indoor radon exposure can be considered premature because
approximately half occur before the age of 70 years. We did not calculate the number of years of
lost life, but given the long life expectancy in France, this figure may be quite high; management of
the risk due to radon is clearly a major public health issue in France.
Of the 512 lung cancer deaths in Franche-Comté during 1999, indoor radon probably caused 1326% whereas 5-12% of lung cancer deaths were attributable to radon exposure in all of France. Our
results must be interpreted according to the number of people in each geological category.
Although 23 to 40% of lung cancer deaths were attributable to radon in granitic areas, granitic areas
represent only 5% of the population and 9% of lung cancer deaths: most of lung cancer deaths
attributable to radon will occur in sedimentary areas. Actions of risk prevention should not be only
focused on granitic territories.

Conclusion
This study is the first lung cancer risk assessment associated with residential radon exposure in
Franche-Comté. When we consider uncertainties related to the exposure–response relation and
geographic variations in radon exposure, we find that the total number of lung cancer deaths in
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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

1999 attributable to indoor radon exposure ranges from 72 to 140. Most of them will occur in
sedimentary areas sometimes regarded as zones of low radon risk. Awareness and risk prevention
campaigns against radon hazard could not be turn only to the most exposed people in granitic areas,
but should rather concern the overall population of the Region.

References
Améon R., Dupuis M., Diez O . (2004) House effect study – experimental site of KersaintPlabennec. (in French) . Rapport DEI/SARG n°04-05 – Fev 2004 - IRSN
BEIR (1999). Health Effects of Exposure to Radon. BEIR VI. Washington, DC:National Academy
Press.
Catelinois O. et al. (2007) Assessment of the health impact related to indoor exposure to radon in
France. BEH n°18-19 155-158. Available at http://www.invs.sante.fr/beh/2007/18_19/index.htm (in
French)
Covello V., Merkhofer M. (1993) Risk Assessment Methods. Approaches for Assessing Health and
Environmental Risks. New York/London:Plenum Press.
Darby S., Hill D., Doll R. (2001) Radon: a likely carcinogen at all exposures. Ann Oncol
12(10):1341–1351.
Darby S., Hill D., Auvinen A., Barros-Dios J.M., et al. (2005) Radon in homes and risk of lung
cancer: collaborative analysis of individual data from 13 European case-control studies. BMJ
330(7485):223
Genay Y. (2005) Identification of potentially high radon exhalation in Franche-Comté. Besançon.
Drass de Franche-Comté. - in French –
INSEE (2000) Recensement INSEE de 1999 de la Population Française, par Commune, Age et
Sexe. Paris : Institut National de la Statistique et des Etudes Economiques. http://www.insee.fr/
IRSN (2000). National Radon Measurement Campaign of natural radioactivity in France. Available
at http://www.irsn.org/index.php?position=radon_5 (in French)
National Research Council. (1983) Risk Assessment in the Federal Government : Managing the
Process. Washington DC: National Academy Press.
OQAI (2003) Enquête Nationale Logements. http://www.air-interieur.org . (in French)
OQAI (2008) Ventilation in French dwellings and schools (in French) – OQAI workshop – June
2008 - Paris. http://www.air-interieur.org .
Pinel J., Fearn T., Darby S.C., Miles J.C.H. (1995) Seasonal correction factors for indoor radon
measurements in the United Kingdom. Radiat Prot Dosimetry 58(2):127–132.
Tirmarche M, Laurier D, Bergot D, Billon S, et al. (2003) Quantification of Lung Cancer Risk after
Low Radon Exposure and Low Exposure Rate: Synthesis from Epidemiological and Experimental
Data. Contract FIGHCT1999-00013. Brussels: European Commission.

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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

Figure 1: Sampling scheme of the Franche-Comté Study

452,124 dwellings in the
Franche-Comté area
19,005 dwellings established
on granitic geology

433,119 dwellings established
on sedimentary geology

254,376 detached houses

178,743 blocks of flats

Random selection

120 dwellings
(65 participations)

659 houses
(328 participations)

128 flats
(61 participations)

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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008
Table 1: Comparison of Franche-Comté measurements extracted from the National Radon Measurement
Campaign and the Franche-Comté Study.
National Radon Measurement
Campaign
(1984 – 1999)

(oct. & nov. 2005)

(volunteers)

(random selection of dwellings)

N
249
318
27
202
88

(%) or [95%CI]

No. of administrative areas
No. of measurements
No. of m. in a bedroom
No. of m. in a living-room
No. of m. in an other room
Arithmetic mean [ 95%CI ]
Geometric mean [ 95%CI ]
No. of m. upper than 200 Bq/m3
No. of m. upper than 400 Bq/m3
No. of m. upper than 1000 Bq/m3

Franche-Comté Study

(%) or [95%CI]

(8.5%)
(63.5%)
(27.7%)

N
306
869
436
433
0

138.2
88.3

[121.2 - 155.2]
[81.0 - 96.2]

134.0
79.6

[121.3 - 146.7]
[74.7 - 84.8]

52
20
3

(16.3%)
(6.3%)
(0.9%)

203
79
12

(23.4%)
(9.1%)
(1.4%)

(50.2%)
(49.8%)
(0.0%)

N: number of dwellings
95% CI: 95% confidence interval of the mean

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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
Vegas NV, September 14-17, 2008. AARST © 2008

Table 2: Comparison of the estimates of lung cancer deaths attributable to indoor exposure in Franche-Comté in
the French National Radon Measurement Campaign and the Franche-Comté Study
French National Radon
Measurement Campaign
Male
Female
Total

Male

Female

Total

437

75

512

437

75

512

147
126

27
23

174
149

93
118

17
21

110
139

61

11

72

21%
27%

23%
29%

21%
27%

14%

14%

14%

Franche-Comté Study

No of total lung cancer deaths (1999)
No of total lung cancers attributable to
indoor radon exposure
Study of miners
EAD
EAC
Indoor study
Darby
Proportion of lung cancers attributable to
indoor radon exposure
Study of miners
EAD
EAC
Indoor study
Darby

34%
29%

36%
31%

34%
29%

EAD: Exposure-age-duration model BEIR VI (BEIR, 1999)
EAC: Exposure-age-concentration model BEIR VI (BEIR, 1999)
Darby: Raw risk model from the joint analysis of the13 European case-control studies (Darby, 2005)

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Proceedings of the American Association of Radon Scientists and Technologists 2008 International Symposium Las
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Table 3: Estimates of lung cancer deaths attributable to indoor exposure in sedimentary and granitic areas of
Franche-Comté. (Indoor radon measurements from the Franche-Comté study)

Sedimentary
structure

Granitic
structure

Total

482

30

512

100
127

10
12

110
139

65

7

72

21%
26%

33%
40%

21%
27%

13%

23%

14%

No of total lung cancer deaths (1999)
No of total lung cancers attributable to
indoor radon exposure
Study of miners
EAD
EAC
Indoor study
Darby
Proportion of lung cancers attributable
to indoor radon exposure
Study of miners
EAD
EAC
Indoor study
Darby

EAD : Exposure-age-duration model BEIR VI (BEIR, 1999)
EAC : Exposure-age-concentration model BEIR VI (BEIR, 1999)
Darby : Raw risk model from the joint analysis of the13 European case-control studies (Darby, 2005)

9