Shared Risk Volatile Organic Compounds Among Chronic Respiratory Diseases: Mediation Effects of System Inflammation

Abstract

Background: Volatile organic compounds (VOCs) are indoor and outdoor air pollution, but the VOCs that were shared across chronic respiratory diseases (CRDs) remained unknown. Meanwhile, the mediating roles of system inflammation need to be further explored.Methods: This study included 9114 adults based on the National Health and Nutrition Examination Survey (NHANES) 2005–2006 and 2011–2018. Internal exposure levels of 14 urinary metabolites of VOC (mVOCs), blood cell count–derived inflammatory biomarkers, and prevalent CRDs, including asthma, chronic bronchitis, and emphysema, were assessed and collected. Associations of single‐ and multiple‐mVOCs with CRDs were assessed by using logistic regression and quantile‐based g‐computation (QGcomp) methods to select the key and shared mVOCs among CRDs. Mediation effects of system inflammation on mVOC‐CRD associations were further evaluated by causal mediation analysis.Results: Increased levels of total 14 mVOCs were associated with increased risk of chronic bronchitis (OR = 1.62, 95% CI: 1.37–1.91), emphysema (OR = 1.73, 95% CI: 1.27–2.35), and both conditions combined (defined as chronic obstructive pulmonary disease, COPD) (OR = 1.61, 95% CI: 1.37–1.88), but not for asthma (OR = 1.07, 95% CI: 0.94–1.21). In both single‐ and multiple‐mVOC exposure models, 8 key mVOCs were COPD associated, including 6 mVOCs (34MHA, AMCC, CEMA, DHBMA, 3HPMA, and MHBMA3) and 5 mVOCs (34MHA, CYMA, 3HPMA, MA, and MHBMA3) that were associated with increased risk of chronic bronchitis and emphysema, respectively. Particularly, 34MHA, 3HPMA, and MHBMA3 were shared risk factors across chronic bronchitis, emphysema, and COPD. Neutrophils mediated the associations of three shared mVOCs with chronic bronchitis (by 5.20%, 7.80%, 6.30%), emphysema (by 6.90%, 9.30%, 9.70%), and COPD (by 5.80%, 8.90%, 7.70%).Conclusions: These findings provide valuable insights into the shared risk mVOCs and mediating roles of neutrophils involved in the pathogenesis of CRDs, which can be useful in developing more effective prevention and intervention strategies for CRDs.