Environmental Lead Exposure Predicts Lower Bone Mineral Density in a Large Taiwanese Population-Based Study

<b>Background:</b> Chronic exposure to environmental lead (Pb) may impair bone metabolism and increase the risk of osteoporosis; however, large-scale epidemiological data remain limited. This study aimed to examine the association between long-term environmental Pb exposure and bone mineral density (BMD) in a nationally representative Taiwanese cohort. <b>Methods:</b> A total of 32,239 participants aged 30-70 years were included after excluding those with missing lead exposure or BMD data. BMD was assessed via calcaneal quantitative ultrasound, and T-scores were calculated. Environmental Pb exposure was estimated using a validated Geo-AI model. Univariable and multivariable linear regression models were used to evaluate associations between Pb exposure and T-scores, adjusting for demographic, lifestyle, comorbidity, and laboratory factors. <b>Results:</b> Among all participants, 7.2% had T-scores < -2.5. These individuals were older, had lower educational attainment, and demonstrated less favorable metabolic and clinical profiles. Multivariable stepwise regression analysis revealed a significant inverse association between lead exposure and baseline T-scores: each 0.001 µg/m³ increase in airborne Pb was independently associated with a -0.013 decrease in baseline T-score (95% CI: -0.017 to -0.009, p < 0.0001). More importantly, in longitudinal analyses, each 0.001 µg/m³ increase in Pb concentration was independently associated with a -0.006 decrease in within-individual T-score change over time (95% CI: -0.010 to -0.003, p = 0.0002). Other significant factors influencing T-scores and T-score changes included age, sex, body mass index, education, exercise, and albumin levels. <b>Conclusions:</b> Chronic environmental Pb exposure is significantly associated with reduced bone mineral density in the general population. These findings underscore the need for environmental risk assessments in osteoporosis screening and public health prevention strategies, particularly in vulnerable populations.