Association between heavy metal exposure and chronic cough: the mediating roles of inflammation.

Background: Right now, epidemiological research examining the connection between blood heavy metal exposure and chronic coughing is still deficient. Therefore, the survey was aimed at the effects of multiple heavy metals on chronic cough.

Method: In this investigation, 2647 individuals from NHANES were included. This study applied multiple statistical models to systematically explore the associations between single and mixed blood metal with the prevalence of chronic cough, including logistic regression, weighted quantile sum (WQS) regression, bayesian kernel machine regression (BKMR), and the Shapley Additive Explanations (SHAP) model. Finally, this research conducted mediation analyses to investigate the mediated effects of inflammation on the association between metal and chronic cough.

Result: In the logistic regression model of single exposure, blood cadmium was positively associated with the prevalence of chronic cough (OR: 3.17; 95% CI: 2.08-4.83). Consistent findings from the WQS, BKMR, and SHAP models revealed that cumulative exposure to multiple blood metals was positively linked to chronic cough, with cadmium emerging as the predominant contributor among the five examined metals. Mediation analyses indicated that WBC and neutrophils, with a proportion of 2.74% and 5.06%, respectively, mediated the link of cadmium in blood with chronic cough.

Conclusion: Exposure to heavy metal mixtures was linked to an increase in the prevalence of chronic cough. And blood cadmium may primarily drive this association, with activated inflammation partially mediating it. Our findings offer novel insights into the impact of blood cadmium to chronic cough.