The Joint Impact of Heavy Metals and Polycyclic Aromatic Hydrocarbons on Periodontitis

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) are significant environmental pollutants, raising growing concerns about their potential impact on human health, particularly oral health. This study aimed to investigate the combined effects of these pollutants on periodontitis (PD) - a prevalent chronic inflammatory disease affecting tooth-supporting structures.

This study utilized the National Health and Nutrition Examination Survey data to examine interactions between HMs, PAHs, and PD. A comprehensive analytical approach included survey-weighted multivariate logistic regression to evaluate individual pollutant exposures, restricted cubic splines to assess dose-response relationships, and advanced models such as Weighted Quantile Sum regression, Quantile G-Computation (qgcomp), and Bayesian Kernel Machine Regression to analyse joint pollutant effects.

Findings revealed significant associations between high levels of certain blood HMs - particularly cadmium (Cd) and lead (Pb) - and increased PD risk. Elevated urinary levels of PAH metabolites were similarly linked to higher risk. Importantly, the study highlights that risk is substantially amplified by the synergistic effects of combined HMs and PAHs exposure. Weighted Quantile Sum, qgcomp, and Bayesian Kernel Machine Regression consistently demonstrated that simultaneous exposures lead to a notably higher PD risk, suggesting that traditional single-pollutant assessments may underestimate health risks.

This study provides robust evidence that exposure to both individual and combined HMs and PAHs significantly elevates PD risk. These findings underscore the importance of considering cumulative and interactive pollutant effects in public health risk assessments.