The Association Between Cobalt and Osteoporosis: A Cross-Sectional Study Utilizing NHANES Data

Objective This study investigates the association between blood cobalt levels and osteoporosis prevalence in the general U.S. population, addressing critical gaps in understanding low-to-moderate environmental exposure effects. Methods We analyzed 2901 adults from NHANES 2017-2020. Blood cobalt concentrations were categorized into quartiles. Multivariable logistic regression, restricted cubic splines (RCS), and Boruta algorithm were employed to assess dose-response relationships, nonlinear associations, and demographic effect modifications, adjusting for sociodemographic, metabolic, and clinical covariates. Results Participants in the highest cobalt quartile showed 32% increased osteoporosis prevalence vs Q1 (OR = 1.32, 95% CI:1.06-1.86). RCS analysis revealed a nonlinear relationship with an inflection point at 0.12 μg/L. Significant effect modifications emerged across multiple strata: females exhibited 91% greater risk elevation than males (OR = 1.91 vs 1.24, p-interaction = 0.022), Non-Hispanic Black participants demonstrated 36-fold higher odds (OR = 36.54, 95% CI:7.17-186.28), and participants with 9-11 years education showed elevated risk (OR = 21.72, 95% CI:1.27-372.63, p-interaction = 0.009). Married individuals exhibited higher risk (OR = 2.08, 95% CI:1.14-3.82) compared to never-married counterparts, though marital status interaction was nonsignificant ( P = 0.721). Conclusions Environmental cobalt levels below current safety thresholds may associate with elevated osteoporosis prevalence, particularly in females and Non-Hispanic Black populations. The nonlinear dose-response relationship (inflection point 0.12 μg/L) suggests threshold effects, advocating for revised biomonitoring standards and targeted screening in vulnerable subgroups.