Exposure to secondhand smoke is a cause of lung cancer in non-smokers.1,2 The risk of developing lung cancer increases with the extent and duration of the exposure. For exposure within the home (typically assessed by examining incidence of disease among the never-smoking spouses of smokers), the evidence suggests that the risk of developing lung cancer due to secondhand smoke is in the range of 20–30%. Lifetime non-smokers exposed to secondhand smoke in the workplace have a similarly elevated risk of developing lung cancer, depending on degree of exposure.2 The mechanisms by which secondhand smoke causes lung cancer are believed to be similar to those observed in smokers, where continuing exposure of the lungs to DNA-damaging material leads to multiple genetic changes that culminate in lung cancer. Non-smokers exposed to secondhand smoke inhale a substantially lower dose of carcinogens than active smokers and have a correspondingly smaller increased risk of lung cancer.2 See Chapter 3, Section 3.4, for a full discussion of active smoking and lung cancer.
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1. Office of Environmental Health Hazard Assessment and California Air Resources Board. Health effects of exposure to environmental tobacco smoke: final report, approved at the Panel's June 24, 2005 meeting. Sacramento: California Environmental Protection Agency, 2005. Available from: http://www.oehha.ca.gov/air/environmental_tobacco/2005etsfinal.html
2. US Department of Health and Human Services. The health consequences of involuntary exposure to tobacco smoke: a report of the Surgeon General. Atlanta, Georgia: US Deptartment of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006. Available from: http://www.cdc.gov/tobacco/data_statistics/sgr/sgr_2006/index.htm