Geographic Exposomics of Cardiac Troponin I Reference Intervals in Chinese Adults: Climate-Topography Coupling-Driven Spatial Prediction and Health Risk Assessment

This study elucidates soil–climate regulatory mechanisms on regional health baselines in China and hydrogeochemical roles in cardiovascular biomarker differentiation. Utilizing data from 26,759 healthy adult samples across 286 Chinese cities/counties, seven core factors were identified via Pearson correlation analysis from 25 indicators, including longitude (X1, r = −0.192, p = 0.009), elevation (X3, r = 0.377, p = 0.001), and precipitation (X7, r = −0.200, p = 0.006). Ridge regression analysis (R2 = 0.714) was subsequently applied to simulate predicted values for 2232 cities/counties. The synergistic effects of soil calcium sulfate content and salinity (X25) on serum cardiac troponin I (cTnI) reference values were rigorously validated, explaining 25.5% of regional cTnI elevation (ΔR2 = 0.183). The findings demonstrate that precipitation leaching and groundwater recharge processes collectively drive a 25.5% elevation in cTnI levels in northwestern regions (e.g., Nagqu, Tibet: altitude > 4500 m, annual sunshine > 3000 h) compared to southeastern areas. To mitigate salinity transport dynamics, optimization strategies targeting soil cation exchange capacity (X18/X19) were proposed, providing a theoretical foundation for designing gradient water treatment schemes in high-calcium-sulfate zones (CaSO4 > 150 mg/L). Crucially, regression equations derived from the predictive model enable the construction of a geographically stratified reference framework for cTnI in Chinese adults, with spatial analysis delineating its latitudinal (R2 = 0.83) and longitudinal (R2 = 0.88) distribution patterns. We propose targeted strategies optimizing soil cation exchange capacity to mitigate sulfate transport in groundwater, informing geographically tailored water treatment and cardiovascular disease prevention efforts. Our findings provide localized empirical evidence critical for refining WHO drinking water sulfate guidelines, demonstrating direct integration of hydrogeochemistry, water quality management, and public health.