Relationship between urinary phthalate metabolites and liver function indicators in the elderly in Northeast China

Phthalates are widespread environmental contaminants, yet their impact on liver function in older adults remains insufficiently understood. This cross-sectional study examined associations between urinary concentrations of 15 phthalate metabolites and serum liver biomarkers in elderly individuals. Metabolite levels were measured using liquid chromatography-tandem mass spectrometry and creatinine-adjusted. Multiple linear regression and Bayesian kernel machine regression (BKMR) models were applied to assess individual and combined effects. Several phthalate metabolites were positively associated with liver enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), and negatively associated with bilirubin (TBIL, DBIL), albumin, and total protein. BKMR analyses confirmed positive mixture effects on ALT, AST, ALP, and gamma-glutamyl transferase (GGT). Body mass index (BMI) modified these associations, suggesting a role of adipose tissue in phthalate accumulation and hepatic effects. These findings highlight potential subclinical liver dysfunction related to phthalate exposure in older adults, warranting further investigation in the context of environmental risk and healthy aging.