The mediating effect of triglycerides and related indices on the association between polycyclic aromatic hydrocarbons and oral health in adults aged ≥ 45 years from the national health and nutrition examination survey 2003–2016

Environmental pollutants are known determinants of oral health; however, the specific effects of polycyclic aromatic hydrocarbons (PAHs) on the oral health of adults aged ≥ 45 years remain poorly understood. This study investigated the association between PAH exposure and oral health and examined the mediating roles of triglyceride (TG) levels, the Triglyceride–Glucose index (TyG), and the Triglyceride–Glucose–Body Mass Index (TyG-BMI). This study utilized data of 4,442 individuals from the National Health and Nutrition Examination Survey. Logistic regression, weighted quantile sum (WQS) regression, and quantile-based g-computation (QGC) analyses assessed associations of urinary PAH metabolites with self-reported poor oral health. Mediation analysis evaluated the roles of TG, TyG, and TyG-BMI. Exposure in the highest quartile to 2-naphthol (2-NAP) and 1-hydroxypyrene (1-OHP) was associated with poor oral health, with odds ratios (95% confidence intervals) of 1.96 (1.34–2.87) and 2.26 (1.51–3.39), respectively. The WQS and QGC models confirmed the overall positive effect of PAH mixtures, driven mainly by 2-NAP and 1-OHP. Mediation analysis revealed that TG, TyG, and TyG-BMI significantly mediated 4.13 to 4.87% of the effect of 2-NAP, whereas TyG-BMI mediated 6.10% of the effect of 1-OHP. A significant interaction between 2-NAP and race was observed in the subgroup analysis. Exposure to specific PAHs is linked to poor oral health and is partially mediated by triglyceride-related pathways. These results underscore the critical need to reducing PAH exposure and control high triglyceride levels to improve oral health outcomes and promote health equity among middle-aged and older adults, providing a scientific basis for enhancing healthy ageing and fostering healthier living environments.