Joint effects of exposure to polybrominated diphenyl ethers (PBDEs) and multiple metals on the risk of depression in...

Synergistic health risks may arise from co-exposure to polybrominated diphenyl ethers (PBDEs) and metals, yet evidence on their joint associations with depression in adults is limited.

We examined individual and joint effects of PBDEs and metals on depression risk in adults.

Data were drawn from the National Health and Nutrition Examination Survey (NHANES, 2005-2016), and 5872 adults were included in the analysis. Associations between individual PBDEs, five metals (cadmium, lead, mercury, calcium, and iron), and depression were assessed using multivariable logistic regression and Restricted Cubic Splines (RCS). Mixture effects were assessed using Weighted Quantile Sum (WQS) regression and Bayesian Kernel Machine Regression (BKMR).

Higher cadmium exposure was linked to increased depression risk (adjusted odds ratio [adj. OR] = 2.55, 95% confidence interval [CI]: 1.84-3.54), whereas mercury was inversely associated (adj. OR = 0.60, 95% CI: 0.45-0.79). Most PBDE congeners showed no linear associations, though BDE28 exhibited an inverted U-shaped dose-response. The PBDE mixture alone was not associated with depression risk. In contrast, the joint PBDE-metal mixture was linked to significantly increased depression risk in both WQS and BKMR models, with BDE209, cadmium, and calcium as predominant contributors. In addition, stronger associations were observed among women, non-Hispanic Whites, and individuals with lower body mass index (BMI).

Co-exposure to PBDEs and metals was correlated with higher depression risk in U.S. adults, with susceptible subgroups identified by gender, race, and BMI. These findings underscore the importance of considering joint pollutant effects on mental health and prevention strategies.