Phthalate exposure and osteoporosis: NHANES associations and integrative in silico prioritization of candidate molecular targets.

BACKGROUND: Phthalates are ubiquitous endocrine-disrupting chemicals, but population-level evidence linking urinary phthalate burden with osteoporosis and the molecular context of these associations remains incomplete. METHODS: We analyzed 8273 participants from the 2003-2010 National Health and Nutrition Examination Survey and integrated exposure-outcome modeling with public transcriptomics, target prediction, weighted gene co-expression network analysis, machine learning, immune-infiltration analysis, single-cell transcriptomics, cell-cell communication, pseudotime analysis, pathway scoring, and molecular docking. RESULTS: Among 8273 participants, 939 met the osteoporosis definition. In the fully adjusted model, the standardized overall phthalate exposure index was associated with higher odds of osteoporosis (OR 1.38, 95% CI 1.28-1.48; P < 0.001). Weighted osteoporosis prevalence increased from 8.7% in the lowest exposure quartile to 16.4% in the highest, and higher exposure was also associated with lower femoral-neck and lumbar-spine bone mineral density. Integrative computational analyses prioritized CXCR4, CEBPB, CD44, YAP1, SPP1, IL6, and MMP9 within inflammation, osteoclast differentiation, and extracellular-matrix pathways. Immune and single-cell analyses localized these candidate targets to osteoporosis-associated macrophage, osteoclast, osteoblast, endothelial, and stromal states. Docking predicted favorable structural compatibility for MEHP-CXCR4 (-8.6 kcal/mol), MBP-CEBPB (-7.9 kcal/mol), and MECPP-YAP1 (-7.4 kcal/mol). CONCLUSION: Higher urinary phthalate burden was associated with osteoporosis-related outcomes, while integrative in silico analyses prioritized candidate molecular and cellular contexts for future experimental testing. These findings do not establish a phthalate-induced causal mechanism.