title: Residential radon exposure and lung cancer in Sweden.
abstract: BACKGROUND
  Residential radon is the principal source of exposure to ionizing radiation in most countries. To determine the implications for the risk of lung cancer, we performed a nationwide case-control study in Sweden.
  
  
  METHODS
  The study included 586 women and 774 men 35 to 74 years of age with lung cancer that was diagnosed between 1980 and 1984. For comparison, 1380 female and 1467 male controls were studied. Radon was measured in 8992 dwellings occupied by the study subjects at some time since 1947. Information on smoking habits and other risk factors for lung cancer was obtained from questionnaires.
  
  
  RESULTS
  Radon levels followed a log-normal distribution, with geometric and arithmetic means of 1.6 and 2.9 pCi per liter (60.5 and 106.5 Bq per cubic meter), respectively. The risk of lung cancer increased in relation to both estimated cumulative and time-weighted exposure to radon. In comparison with time-weighted average radon concentrations up to 1.4 pCi per liter (50 Bq per cubic meter), the relative risk was 1.3 (95 percent confidence interval, 1.1 to 1.6) for average radon concentrations of 3.8 to 10.8 pCi per liter (140 to 400 Bq per cubic meter), and it was 1.8 (95 percent confidence interval, 1.1 to 2.9) at concentrations exceeding 10.8 pCi per liter. The estimates of risk were in the same range as those projected from data in miners. The interaction between radon exposure and smoking with regard to lung cancer exceeded additivity and was closer to a multiplicative effect.
  
  
  CONCLUSIONS
  Residential exposure to radon is an important cause of lung cancer in the general population. The risks appear consistent with earlier estimates based on data in miners.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Pershagen
authors.forename: G
authors.initials: G
authors.lastname: Akerblom
authors.forename: O
authors.initials: O
authors.lastname: Axelson
authors.forename: B
authors.initials: B
authors.lastname: Clavensjö
authors.forename: L
authors.initials: L
authors.lastname: Damber
authors.forename: G
authors.initials: G
authors.lastname: Desai
authors.forename: A
authors.initials: A
authors.lastname: Enflo
authors.forename: F
authors.initials: F
authors.lastname: Lagarde
authors.forename: H
authors.initials: H
authors.lastname: Mellander
authors.forename: M
authors.initials: M
authors.lastname: Svartengren
mesh_terms: D000328:Adult; D000368:Aged; D000396:Air Pollutants, Radioactive / Q000009:adverse effects* / Q000032:analysis; D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D016022:Case-Control Studies; D016001:Confidence Intervals; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D011886:Radon / Q000009:adverse effects* / Q000032:analysis; D012044:Regression Analysis; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013548:Sweden / Q000453:epidemiology
chemical_list: D000396:Air Pollutants, Radioactive; D011886:Radon