Associations of polyfluoroalkyl chemicals and chronic bronchitis in the U.S. adults

Abstract Perfluoroalkyl chemicals (PFCs), present everywhere in the environment, have been proven to impact the respiratory system of children and adolescents adversely. Nevertheless, their effects on chronic bronchitis (CB), one of the most common clinical phenotypes of COPD, have not been characterized. We aimed to evaluate relationships between serum PFCs and CB in adults, including the presence of self-reported CB, respiratory symptoms, and levels of inflammatory biomarkers in the blood. Participants aged ≥ 40 years (N = 2862) in cross-sectional research from the 2007–2012 NHANES were considered and investigated their serum levels of 12 major PFC. Multivariable logistic or linear regression was used for the analyses of relationships between serum PFCs and CB, and subgroup analyses of the participants were carried out based on their self-reported asthma. In multivariable-adjusted models, we found that serum levels of total PFCs as well as several individual PFCs, such as PFUA, PFDE, PFOS, PFNA, MPAH, PFOA, and PFHxS, especially the PFUA and PFDE, were negatively correlated with the prevalence of CB, respiratory symptoms, and inflammatory biomarkers in the whole population. Subgroup analyses showed the potential modification effects of asthma on the associations of PFCs levels with respiratory symptoms and inflammatory biomarkers, including a statistically significant negative correlation with respiratory symptoms (chronic cough, coughing phlegm, wheezing, and shortness of breath) and levels of inflammatory blood biomarkers (CRP, WBC, and NEU) only in participants without asthma; and a statistically significant positive correlation with respiratory symptoms (chronic cough, coughing phlegm, and shortness of breath) and eosinophil (EOS) counts in participants with asthma. Our preliminary findings suggested that there are associations between serum levels of PFCs and CB-related clinical indicators in adults aged ≥ 40 years and that asthma factors may influence those relationships. Further replications of the associations in generalizable prospective cohort studies are warranted.