Impact of Environmental Heavy Metal Exposure on Cardiovascular Disease Mortality

Background: Cardiovascular disease (CVD) is the primary cause of mortality worldwide, and heavy metal exposure, including lead (Pb), cadmium (Cd), and mercury (Hg), significantly impacts this global burden of CVD. Heavy metal-related cardiovascular toxicity results from their ability to induce oxidative stress, inflammation, endothelial dysfunction, and dysregulation of lipid metabolism. We aimed to investigate the association between blood concentrations of Pb, Cd, and Hg and cardiovascular mortality in a representative U.S. adult population. Method: Using the 1999–2018 National Health and Nutrition Examination Survey (NHANES) data, we examined the association of blood Pb, Cd, and Hg levels with CVD mortality. Pb, Cd, and Hg levels were transformed into quartiles. Metal levels were categorized into quartiles, and Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for demographic, clinical, and lifestyle covariates Results: We included 55,081 participants between 1999 and 2018, of whom 4.5% (n=2402) experienced CVD-related death. Those with CVD mortality were more likely to be male (52%), White (78%), and to have a higher prevalence of hypertension, diabetes, obesity, and prior CVD, They also had significantly higher mean levels of Pb (2.57 vs. 1.59 μg/L, p<0.01) and Cd (0.68 vs. 0.51 μg/L, p<0.01) but lower mean levels of Hg (1.36 vs. 1.58 μg/L, p<0.01). In multivariable models, higher Pb (3rd and 4th quartiles) and Cd (4th quartile) levels were significantly associated with increased CVD mortality, whereas higher Hg levels (3rd and 4th quartiles) were inversely associated with CVD mortality. Conclusions: In this nationally representative cohort, blood lead and cadmium were positively associated with cardiovascular mortality, whereas mercury showed an inverse association. These findings highlight the need for continued monitoring of environmental metal exposures and their potential cardiovascular implications.