Association of Mixed Metal Exposures with Cardiovascular Disease: Insights from a Population-Based Study

Environmental metal exposure has been increasingly recognized as a contributor to cardiovascular toxicity, yet the effects of single and mixed metal burdens, as well as susceptible population subgroups, remain insufficiently characterized. This study aimed to investigate the associations of blood copper (Cu), zinc (Zn), Cu/Zn ratio, selenium (Se), lead (Pb), cadmium (Cd), total mercury (HgT), and manganese (Mn) with cardiovascular disease (CVD), and to evaluate the joint association of multiple metal exposures and potential heterogeneity across population subgroups. Data from 1,967 participants (211 CVD cases) in the 2011-2016 NHANES were analyzed. Spearman correlation, logistic regression, restricted cubic spline (RCS), weighted quantile sum (WQS) regression, and quantile-based g-computation (QGcomp) were applied to assess associations of single metals and mixtures with CVD. Subgroup analyses were conducted by demographics and health conditions. Network pharmacology was applied to identify candidate pathways and toxicological targets. CVD patients had higher levels of Cu, Cu/Zn ratio, Pb, and Cd, but lower levels of Zn, HgT, and Mn. Spearman analyses showed Cd (rho = 0.114) and Pb (rho = 0.111) have positive associations with CVD, whereas Mn has a negative connection (rho=-0.069) (all P < 0.05). In quartile-based logistic regression, Cd showed the most consistent positive association with CVD, with participants in the highest quartile having higher odds of CVD in the fully adjusted model (OR = 2.29, 95% CI: 1.37-3.87, P = 0.002). The Cu/Zn ratio was positively associated with CVD in partially adjusted models, but the association was attenuated and no longer statistically significant after full adjustment (OR = 1.55, 95% CI: 0.94-2.57, P = 0.089). RCS revealed linear correlations between Pb, Cd and Mn with prevalent CVD. The WQS index was positively associated with higher odds of CVD (OR = 1.70, 95% CI: 1.16-2.52, P = 0.008), with Cd, the Cu/Zn ratio, and Pb showing the largest positive weights. QGcomp similarly indicated a positive overall mixture association (OR = 1.64, 95% CI: 1.10-2.45, P = 0.014), while Mn contributed in the negative direction. Subgroup analyses indicated that specific metals exerted positive contributions in vulnerable populations, including younger males, smokers, drinkers, elderly, hypertensive, and low-BMI groups. GAPDH, AKT1, CTNNB1, MYC, TNF, and TP53 were predicted to be key targets. Elevated blood Cd showed the most consistent positive association with CVD across individual and mixture-based analyses. The Cu/Zn ratio and Pb also contributed substantially to the positive association of the metal mixture with CVD, although the independent association of the Cu/Zn ratio was attenuated after full multivariable adjustment. Mn showed a potential inverse association. These findings highlight the toxicological relevance of metal mixtures in cardiovascular disease and underscore the need for mechanistic studies to establish causality.