Residential radon exposure and lung cancer--an epidemiological study of Norwegian municipalities

Our plain-English summary of Residential radon exposure and lung cancer--an epidemiological study of Norwegian municipalities, by K. Magnus, A. Engeland, B.M. Green, et al (International Journal of Cancer, 1994).

The study

• Authors: K. Magnus, A. Engeland, B.M. Green, T. Haldorsen, C.R. Muirhead, T. Strand
• Journal: International Journal of Cancer
• Published: 1994;58(1):1-7
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The study is based on a collaboration between the Cancer Registry of Norway, the Norwegian Radiation Protection Authority, and National Radiological Protection Board (NRPB, UK). The association between indoor radon exposure and lung cancer was studied in 427 municipalities. NRPB detectors were sent to 10,000 households, and 7,500 of the detectors were returned. Data from a nation-wide survey of smoking habits in 1964-1965 were available. Data on asbestos exposure were also used in a regression analysis. The reporting to the Cancer Registry of all new cases of cancer is fairly complete, as hospital departments and institutes of pathology are obliged to report all cancer cases. The histologically confirmed lung cancer cases were grouped into squamous-cell carcinoma, small-cell carcinoma, adenocarcinoma and other or non-specified histological types. The age-adjusted rate of lung cancer by histological type was the dependent variable in the regression analysis. A consistent increase in incidence of lung cancer was seen with increasing tobacco consumption, but no positive trend could be shown with increasing radon exposure in the descriptive presentation of the data. In the regression analysis, however, the incidence of small-cell anaplastic lung tumors in females increased significantly with increasing radon exposure. When based on the regression coefficients, the fraction of lung cancers attributable to radon is about 2-4%. However, systematic errors cannot be excluded in an ecological study such as presented here.

In plain English

This ecological study compared areas rather than individuals. It related lung cancer rates in 427 Norwegian municipalities (423 for males) to average indoor radon levels, smoking habits and an asbestos indicator. Radon was measured with detectors placed in main bedrooms of sampled dwellings, and 7,500 of 10,000 detectors were returned. Smoking data came from a 1964-1965 postal survey. Asbestos exposure was estimated from the share of male workers in occupations that an expert classified as having medium or heavy asbestos exposure in the 1970 census. Lung cancers diagnosed in 1979-1988 were analysed by tissue type. Lung cancer rose with tobacco consumption. The asbestos variables were highly statistically significant for males, and the authors also reported an asbestos effect for females. No radon effect was found in males. In females, radon was significantly associated only with small-cell carcinoma: a 10 Bq m-3 reduction corresponded to 0.091 (95% CI 0.026-0.156) or 0.215 (95% CI 0.021-0.409) fewer cases per 100,000 per year. The authors estimated that about 2-4% of lung cancers may be attributable to residential radon. They cautioned that systematic errors cannot be excluded in an ecological study.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Ecological study using municipalities as the unit of analysis, with descriptive tables and population-weighted multiple regression
• Who was studied: 427 Norwegian municipalities (423 in the analyses for males). Lung cancer cases diagnosed 1979-1988 came from the Cancer Registry of Norway: 10,499 in males and 3,132 in females. Oslo and Kristiansand were excluded, as were six municipalities from which no radon detectors were returned. Radon detectors were sent to a sample of 10,000 dwellings, and 7,500 were returned. 14,800 of 18,600 people sampled completed the 1964-1965 smoking survey.
• Exposure: The main exposure was indoor radon, measured in the main bedroom over 6 months in 1987-1989 and expressed in Bq m-3. Average daily tobacco consumption was also studied. Asbestos burden was measured by two indicator variables based on the percentage of male workers in occupations an expert classified as having medium or heavy asbestos exposure in the 1970 census. No fiber types are named.
• Main results:
  • In the descriptive tables, small-cell and squamous-cell carcinoma rates rose almost consistently with tobacco consumption. There was no positive trend with radon exposure.
  • Males: each 1 g increase in adjusted mean daily tobacco consumption corresponded to an annual increase of 6 new lung cancer cases per 100,000 males.
  • Males: the asbestos variable gave highly statistically significant results.
  • Males: no effect of radon exposure could be demonstrated.
  • Females: effects of tobacco consumption and asbestos exposure were also demonstrated, with estimates much smaller than for males.
  • Females: radon coefficients for total lung cancer incidence were positive but not significantly different from zero. Both coefficients for small-cell carcinoma were significantly larger than zero.
  • Females: a 10 Bq m-3 reduction in radon would correspond to an annual reduction in small-cell lung carcinoma of 0.091 per 100,000 (95% CI 0.026-0.156; observed estimates) or 0.215 per 100,000 (95% CI 0.021-0.409; composite estimates). The authors put this at 2 or 4 cases per year among 2.1 million Norwegian women.
  • Under stated assumptions, the authors estimated about 30-60 radon-attributable lung cancer cases per year in both sexes. That is about 2-4% of roughly 1,600 annual cases (printed as '24%' in the scanned text).
• The authors' conclusion: The authors concluded that the study demonstrated effects of smoking and asbestos, but no increasing lung cancer risk across radon quintiles. The only evidence of a radon effect was a slight increase in small-cell lung carcinoma among women.
• Limitations the authors state:
  • Systematic errors cannot be excluded in an ecological study.
  • Adjusting for smoking at the area level is less effective than in studies with individual-level information.
  • Radon measured in 1987-1989 was probably higher than in preceding decades because of better insulation of modern dwellings.
  • About 2,500 detectors were not returned, which might have biased the measurements. The authors judged this unlikely because there was no geographical pattern in response.
  • Radon estimates for small municipalities rested on few observations, which might weaken the estimated exposure-response relationship.
  • Smoking was surveyed in 1964-1965, well before the 1979-1988 diagnoses. Tobacco estimates were imprecise for small municipalities.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Cancer Registry, Habit, Asbestos Exposure, Pathology, Carcinoma, Adenocarcinoma.

Related studies

• Increased lung cancer risk due to residential radon in a pooled and extended analysis of studies in Germany — H.E. Wichmann, A.S. Rosario, et al. (2005)
• Case-control study on lung cancer and residential radon in western Germany — L. Kreienbrock, M. Kreuzer, et al. (2001)
• Residential radon and risk of lung cancer in Eastern Germany — M. Kreuzer, J. Heinrich, et al. (2003)
• Indoor radon levels in urban Hyderabad area, Andhra Pradesh, India — M. Sreenath Reddy, P. Yadagiri Reddy, et al. (2008)
• Arsenic, asbestos and radon: emerging players in lung tumorigenesis — R. Hubaux, D.D. Becker-Santos, et al. (2012)
• Risk factors for lung cancer in Iowa women: implications for prevention — J.S. Neuberger, J.D. Mahnken, et al. (2006)

Browse more research in International Journal of Cancer, or return to medical research.