Second-Hand Smoke Exposure and Risk of Lung Cancer Among Nonsmokers in the United States: A Systematic Review and Meta-Analysis.

This study aims to explore the link between exposure to tobacco smoke among nonsmokers and the risk of lung cancer in the United States. We searched six databases for studies on second-hand smoke (SHS) and lung cancer following PRISMA guidelines. Following the random effects model and specific statistical methods, our meta-analysis analyzed studies based on SHS exposure type. A total of 19 eligible studies were included in the review and 15 in the meta-analysis. We covered exposure from parents (childhood), spouses and partners (household), and work-related exposure (colleagues), with higher risk among non-smoking children and domestic partners. Findings reveal a consistent link between SHS exposure and increased lung cancer risk for this population (exposure effect sizes: 1.05-3.11). Analysis of childhood SHS exposure reveals a distinct increased risk associated with parental exposure. For nonsmokers living with smoking spouses, there is a marked 41% increase in risk. Higher risk was associated with more and more prolonged SHS exposure. Exposure to SHS in the workplace shows a correlation with lung cancer risk. Our findings highlight increased SHS-related lung cancer risk, particularly among non-smoking children and domestic partners, intensifying with the amount and duration of exposure, indicating the significant impact of SHS within domestic environments.