title: Smoky coal, tobacco smoking, and lung cancer risk in Xuanwei, China.
abstract: OBJECTIVE
  Lung cancer rates in Xuanwei are the highest in China. In-home use of smoky coal has been associated with lung cancer risk, and the association of smoking and lung cancer risk strengthened after stove improvement. Here, we explored the differential association of tobacco use and lung cancer risk by the intensity, duration, and type of coal used.
  
  
  METHODS
  We conducted a population-based case-control study of 260 male lung cancer cases and 260 age-matched male controls. Odds ratios (OR) and 95% confidence interval (CI) for tobacco use was calculated by conditional logistic regression.
  
  
  RESULTS
  Use of smoky coal was significantly associated with an increased risk of lung cancer, and tobacco use was weakly and non-significantly associated with lung cancer risk. When the association was assessed by coal use, the cigarette-lung cancer risk association was null in hazardous coal users and elevated in less hazardous smoky coal users and non-smoky coal users. The risk of lung cancer per cigarette per day decreased as annual use of coal increased (>0-3 tons: OR: 1.09; 95% CI: 1.03-1.17; >3 tons: OR: 0.99; 95% CI: 0.95-1.03). Among more hazardous coal users, attenuation occurred at even low levels of usage (>0-3 tons: OR: 1.02; 95% CI: 0.91-1.14; >3 tons: OR: 0.94; 95% CI: 0.97-1.03).
  
  
  CONCLUSIONS
  We found evidence that smoky coal attenuated the tobacco and lung cancer risk association in males that lived in Xuanwei, particularly among users of hazardous coal where even low levels of smoky coal attenuated the association. Our results suggest that the adverse effects of tobacco may become more apparent as China's population continues to switch to cleaner fuels for the home, underscoring the urgent need for smoking cessation in China and elsewhere.
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States; School of Public Health, Yale University, New Haven, CT 06520, United States. Electronic address: Christopher.kim@nih.gov.
authors: Christopher
authors: C
authors: Kim
authors: College of Public Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand.
authors: Robert S
authors: RS
authors: Chapman
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States.
authors: Wei
authors: W
authors: Hu
authors: Institute of Environmental Health and Engineering, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors: Xingzhou
authors: X
authors: He
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States; Albert Einstein College of Medicine, Bronx, NY 10461, United States.
authors: H Dean
authors: HD
authors: Hosgood
authors: Weill Medical College of Cornell University, New York, NY 10021, United States.
authors: Larry Z
authors: LZ
authors: Liu
authors: Department of Radiology and Ophthalmology, The Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD 21287, United States.
authors: Hong
authors: H
authors: Lai
authors: Forest Laboratories, Inc., Jersey City, NJ 07311, United States.
authors: Wei
authors: W
authors: Chen
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States.
authors: Debra T
authors: DT
authors: Silverman
authors: Institute for Risk Assessment, Utrecht University, Utrecht, The Netherlands.
authors: Roel
authors: R
authors: Vermeulen
authors: School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
authors: Linwei
authors: L
authors: Tian
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States; School of Public Health, Yale University, New Haven, CT 06520, United States.
authors: Bryan
authors: B
authors: Bassig
authors: Interfaith Medical Center, Brooklyn, NY 11213, United States.
authors: Min
authors: M
authors: Shen
authors: School of Public Health, Yale University, New Haven, CT 06520, United States.
authors: Yawei
authors: Y
authors: Zhang
authors: School of Public Health, Yale University, New Haven, CT 06520, United States.
authors: Shuangge
authors: S
authors: Ma
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States.
authors: Nathaniel
authors: N
authors: Rothman
authors: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States.
authors: Qing
authors: Q
authors: Lan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D003031:Coal; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012306:Risk; D012906:Smoke / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D003031:Coal; D012906:Smoke
keywords: China; Coal; Epidemiology; Global health; Indoor air pollution; Lung cancer; Tobacco