H. Baysson

Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies

Abstract Objective To determine the risk of lung cancer associated with exposure at home to the radioactive disintegration products of naturally occurring radon gas Design Collaborative analysis of individual data from 13 case-control studies of residential radon and lung cancer. Setting Nine European countries. Subjects 7148 cases of lung cancer and 14 208 controls. Main outcome measures Relative risks of lung cancer and radon gas concentrations in homes inhabited during the previous 5-34 years measured in becquerels (radon disintegrations per second) per cubic metre (Bq/m3) of household air. Results The mean measured radon concentration in homes of people in the control group was 97 Bq/m3, with 11% measuring > 200 and 4% measuring > 400 Bq/m3. For cases of lung cancer the mean concentration was 104 Bq/m3. The risk of lung cancer increased by 8.4% (95% confidence interval 3.0% to 15.8%) per 100 Bq/m3 increase in measured radon (P = 0.0007). This corresponds to an increase of 16% (5% to 31%) per 100 Bq/m3 increase in usual radon—that is, after correction for the dilution caused by random uncertainties in measuring radon concentrations. The dose-response relation seemed to be linear with no threshold and remained significant (P = 0.04) in analyses limited to individuals from homes with measured radon < 200 Bq/m3. The proportionate excess risk did not differ significantly with study, age, sex, or smoking. In the absence of other causes of death, the absolute risks of lung cancer by age 75 years at usual radon concentrations of 0, 100, and 400 Bq/m3 would be about 0.4%, 0.5%, and 0.7%, respectively, for lifelong non-smokers, and about 25 times greater (10%, 12%, and 16%) for cigarette smokers. Conclusions Collectively, though not separately, these studies show appreciable hazards from residential radon, particularly for smokers and recent ex-smokers, and indicate that it is responsible for about 2% of all deaths from cancer in Europe.

Indoor radon and lung cancer in France.

Background: Several case-control studies have indicated an increased risk of lung cancer linked to indoor radon exposure; others have not supported this hypothesis, partly because of a lack of statistical power. As part of a large European project, a hospital-based case-control study was carried out in 4 areas in France with relatively high radon levels. Methods: Radon concentrations were measured in dwellings that had been occupied by the study subjects during the 5- to 30-year period before the interview. Measurements of radon concentrations were performed during a 6-month period using 2 Kodalpha LR 115 detectors (Dosirad, France), 1 in the living room and 1 in the bedroom. We examined lung cancer risk in relation to indoor radon exposure after adjustment for age, sex, region, cigarette smoking, and occupational exposure. Results: We included in the analysis 486 cases and 984 controls with radon measures in at least 1 dwelling. When lung cancer risk was examined in relation to the time-weighted average radon concentration during the 5- to 30-year period, the estimated relative risks (with 95% confidence intervals) were: 0.85 (0.59–1.22), 1.19 (0.81–1.77), 1.04 (0.64–1.67), and 1.11 (0.59–2.09) for categories 50–100, 100–200, 200–400, and 400+ becquerels per cubic meter (Bq/m3), respectively (reference <50 Bq/m3). The estimated relative risk per 100 Bq/m3 was 1.04 (0.99–1.11) for all subjects and 1.07 (1.00–1.14) for subjects with complete measurements. Conclusions: Our results support the presence of a small excess lung cancer risk associated with indoor radon exposure after precise adjustment on smoking. They are in agreement with results from some other indoor radon case-control studies and with extrapolations from studies of underground miners.

Exposition domestique au radon et risque de cancer du poumon : Les résultats d'une étude épidémiologique menée en France

INTRODUCTION Several epidemiological studies have indicated an increased risk of lung cancer associated with indoor radon exposure. As part of a large European project, a hospital based case-control study was carried out in four regions of France: Auvergne, Brittany, Languedoc-Roussillon and Limousin. MATERIAL AND METHODS Individual data on demographic characteristics, residential history, smoking and occupational exposures were collected during face-to-face interviews. Radon concentrations were measured in each dwelling occupied by the subject during the 30-year period prior to the interview. RESULTS 486 cases and 984 controls were included in the study. After adjustment for age, sex, region, smoking history and occupational exposure, the risk of lung cancer increased by 4% per 100 Bq/m(3), when considering cumulative exposure in the 30 years prior to diagnosis. CONCLUSION The study indicates a positive association between lung cancer risk and indoor radon exposure. The risk estimate per unit of exposure is in agreement with other recently published indoor case-control studies.Resume Introduction Les resultats des etudes epidemiologiques recentes indiquent une augmentation du risque de cancer du poumon liee a l’inhalation de radon, gaz radioactif d’origine naturelle present dans l’habitat. Dans le cadre d’un vaste programme europeen, une etude cas-temoins a ete menee dans quatre regions francaises : Auvergne, Bretagne, Languedoc-Roussillon et Limousin. Materiels et methodes Les donnees individuelles sur les caracteristiques socioprofessionnelles, l’historique des habitations occupees, le tabagisme et les expositions professionnelles ont ete collectees au cours d’interviews en face-a-face. La concentration de radon a ete mesuree dans chacune des habitations occupees par le sujet au cours des 30 annees precedant son inclusion dans l’etude. Resultats 486 cas de cancer du poumon et 984 temoins ont ete inclus dans l’etude. Apres ajustement sur l’âge, le sexe, la region, le tabagisme actif et les expositions professionnelles, une augmentation du risque de cancer du poumon est observee, fonction de l’exposition au radon cumulee durant les 30 annees precedant le diagnostic de cancer. Cette augmentation est de 4% pour 100 Bq/m3. Conclusion Cette etude indique une association positive entre le risque de cancer du poumon et l’exposition domestique au radon. L’estimation du risque par unite d’exposition est concordante avec celles provenant d’autres publications recentes.

Exposition à la scanographie dans l’enfance et risque de cancer à long terme. Une synthèse des études épidémiologiques récentes

Amongst medical exams requiring ionizing radiation, computed tomography (CT) scans are used more frequently, including in children. These CT examinations are associated with absorbed doses that are much higher than those associated with conventional radiology. In comparison to adults, children have a greater sensitivity to radiation and a longer life span with more years at cancer risks. Five epidemiological studies on cancer risks after CT scan exposure during childhood were published between 2012 and 2015. The results of these studies are consistent and show an increase of cancer risks in children who have been exposed to several CT scans. However, methodological limits due to indication bias, retrospective assessment of radiation exposure from CT scans and lack of statistical power are to be taken into consideration. International projects such as EPI-CT (Epidemiological study to quantify risks for pediatric computerized tomography and to optimize dose), with a focus on dosimetric reconstruction and minimization of bias will provide more precise results. In the meantime, available results reinforce the necessity of justification and optimization of doses.

SynthèseExposition à la scanographie dans l’enfance et risque de cancer à long terme. Une synthèse des études épidémiologiques récentesExposure to CT scans in childhood and long-term cancer risk: A review of epidemiological studies

Amongst medical exams requiring ionizing radiation, computed tomography (CT) scans are used more frequently, including in children. These CT examinations are associated with absorbed doses that are much higher than those associated with conventional radiology. In comparison to adults, children have a greater sensitivity to radiation and a longer life span with more years at cancer risks. Five epidemiological studies on cancer risks after CT scan exposure during childhood were published between 2012 and 2015. The results of these studies are consistent and show an increase of cancer risks in children who have been exposed to several CT scans. However, methodological limits due to indication bias, retrospective assessment of radiation exposure from CT scans and lack of statistical power are to be taken into consideration. International projects such as EPI-CT (Epidemiological study to quantify risks for pediatric computerized tomography and to optimize dose), with a focus on dosimetric reconstruction and minimization of bias will provide more precise results. In the meantime, available results reinforce the necessity of justification and optimization of doses.

Morbidity study of French nuclear workers from Areva NC

Objectives To conduct a morbidity study among all French AREVA NC workers. Methods The study is based largely on data collected from Occupational Medicine services of AREVA NC using the software called “Chimed” implemented since 1994. For each worker, all incident health events, as well as administrative data, were registered in the Chimed database, during medical visits with an occupational physician. Standardised incidence rates were calculated for major categories of diseases. Results The morbidity study of French nuclear workers is currently carried out in 5 specific sites in France: Ile-de-France, Pierrelatte, Malvési, Marcoule and La Hague, using the same protocol. Data regarding Ile de France (1710 workers), Pierrelatte (4540 workers) and Malvési (378 workers) have already been analysed. Except for Ile-de-France, most workers were men and technician workers. Traumatic diseases were the most frequently reported diseases for the site of Pierrelatte and diseases of the musculoskeletal system were the most frequently reported for the site of Ile-de-France and for the site of Malvési l. Conclusions In contrast with mortality, morbidity studies in occupational health are scarce in France. The Chimed database provides an overview of the health status of the AREVA-NC workers. In order to increase the statistical power of the study, a joint analysis of our site-specific data, will be undertaken. Besides, medical data will be linked to exposure data, giving the possibility to conduct analytical studies on morbidity and exposure among nuclear workers. Variation factors on the incidence of major diagnosed diseases will be also further investigated.

Lung doses due to multiple radiation exposures and risk of lung cancer death among French uranium miners

Objectives The study aims to assess the risk of lung cancer death associated with lung doses due to radon gas and its short-lived progeny (RnP), long-lived radionucleides (LLR) and external γ rays in the French cohort of uranium miners. Methods The cohort included 3271 exposed miners followed from 1956 through 1999. Annual exposures were assessed individually and lung doses were calculated according to the Human Respiratory Tract Model (Publication 66 of the International Commission on Radiological Protection). Poisson regression was used to fit linear excess relative risk (ERR) models to estimate dose-risk relationships. Results The mean absorbed lung dose due to α emitters was 78 milliGray (mGy), and to non-α emitters, 56 mGy. RnP accounted for 97% of the α absorbed dose. A significant ERR of lung cancer death was associated with the total absorbed lung dose (ERR/Gy (95% CI) = 2.9 (0.8–7.5)), the α absorbed dose (4.58 (1.3–10.9)) and RnP (4.6 (1.3–11.2)). Assuming a value of 20 for the relative biological effectiveness of α particles in lung cancer induction, the ERR/Gy-equivalent for the total-weighted lung dose was 0.2 (0.1–0.5), similar to that for the α-weighted and RnP-weighted lung dose. Conclusions These first results about lung doses from the European Alpha-Risk project, with regard to the lung dose distribution, support the major role of RnP in the risk of lung cancer death.

Risk of cancer in relation to natural radiation, including radon: Evidence from epidemiological studies

A review of recently published epidemiological studies on populations exposed to natural background ionizing radiation is proposed. The advantages and disadvantages of different types of epidemiological studies as well as the uncertainty linked to multiple exposures are discussed. As radon is the greatest source of natural radiation, particular attention is given to quantification of risk obtained through cohort studies of uranium miners and after joint analysis of case‐control studies on lung cancer and residential radon.