Associations of non-essential metal/metalloids and their mixture with liver function in Chinese older adults: the mediating roles of lipid profiles

The liver is vulnerable to damage from environmental pollutants, but evidence on the effects of non-essential metal/metalloid (NEM) mixture on liver function and their mechanisms remains limited. The study aimed to explore the correlations between individual NEMs and their combinations with liver function, and the mediating roles of lipid profiles. The research involved 2642 individuals aged 60 and older in China. Urine concentrations of arsenic (As), cesium (Cs), barium (Ba), thallium (Tl), and cadmium (Cd) were analyzed using ICP-MS. Liver function was assessed based on the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and albumin (ALB). To evaluate the individual and combined effects of these NEMs on liver function, linear regression, restricted cubic splines (RCS), weighted quantile sum (WQS), quantile g-computation (QGC), and Bayesian kernel machine regression (BKMR) models were utilized. Mediation analyses were conducted to explore the potential role of lipid profiles in NEM-liver function relations. Adjusted linear regression revealed positive associations of Tl with ALT (β = 0.044, 95 % CI: 0.022 to 0.066) and AST (β = 0.019, 95 % CI: 0.004 to 0.035), and negative associations of Cs (β = -0.015, 95 % CI: -0.020 to -0.010), Tl (β = -0.010, 95 % CI: -0.015 to -0.005), and Cd (β = -0.019, 95 % CI: -0.024 to -0.014) with ALB. The RCS model confirmed these linear relationships. Mixture models consistently demonstrated a positive association between the NEM mixture and ALT/AST, primarily driven by Tl, and a negative association with ALB, predominantly influenced by Cd. Mediation analyses suggested triglycerides and total cholesterol partially mediated the associations between Tl, the NEM mixture, and liver function. In conclusion, the NEM mixture, mainly driven by Tl and Cd, is linked to liver function impairment, with lipid profiles potentially mediating these effects. More research is needed to confirm these findings and clarify the mechanisms.