Impact of toxic metal exposure on blood pressure: Insights into individual and combined effects with Bayesian kernel machine regression

Hypertension is a leading global health issue, influenced by environmental factors such as metal exposure. Metals elements like arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), and nickel (Ni) can disrupt blood pressure regulation through oxidative stress and endothelial dysfunction. Understanding their individual and combined effects is essential for effective prevention and management strategies. This study assessed the association between metal exposure and blood pressure, examining the risk of hypertension due to individual and combined metal exposures among residents of Shaanxi Province. A total of 336 participants were surveyed between June and August 2022. Data on demographics, lifestyle, and health were collected via questionnaires, physical exams, and hair samples. Concentrations of As，Cd, Cr, Hg, Pb, and Ni were analyzed using inductively coupled plasma mass spectrometry. Linear and logistic regression models, Restricted Cubic Spline (RCS) analyses, and Bayesian kernel machine regression (BKMR) evaluated dose-response relationships and combined metal exposure effects. The results showed that hypertensive participants (n = 199) had significantly higher Cr, Pb, and Ni levels than non-hypertensives (n = 137) (P < 0.05). Cr and Pb concentrations were positively associated with both blood pressure and hypertension risk (e.g., for Cr: β=12.8, 95% CI: 2.8-22.7; OR=2.1, 95% CI: 1.1-4.0), with dose-response relationships observed. Combined exposure analyses revealed Cr and Ni increased hypertension risk, while As and Cd appeared protective. BKMR indicated lead had the highest posterior inclusion probability (PIP = 0.984). Cr and Pb exposure are major contributors to hypertension risk, with significant interactions among metals influencing their combined effects. Findings highlight the need for targeted strategies to mitigate environmental metal exposure and its health impacts.