Rare Earth Element Exposure and Gestational Diabetes Mellitus: Insights into the Coexistence of Environmental Exposure Risks and Benefits

The extensive use of rare earth elements (REEs) has prompted concerns regarding their potential detrimental impact on human health. This study investigated the association between early pregnancy exposure to REEs and gestational diabetes mellitus (GDM) using a prospective nested case-control study. We employed generalized linear models (GLM) to assess individual associations, as well as quantile g-computation (QGC) and Bayesian Kernel Machine Regression (BKMR) for mixture effect analysis. Our findings reveal complex bidirectional associations between REE exposure and both GDM and glucose homeostasis. In multivariate logistic regression analysis, gadolinium (Gd) was significantly associated with a reduced risk of GDM [OR = 0.18, 95% CI: 0.04, 0.85], while dysprosium (Dy) was linked to an increased risk [OR = 7.30, 95% CI: 1.29, 41.22]. Furthermore, Dy [beta = 0.08, 95% CI: 0.02, 0.14 for FBG], cerium (Ce) [beta = 0.28, 95% CI: 0.01, 0.55 for 1hPBG], and europium (Eu) [beta = 0.10, 95% CI: 0.04, 0.17 for 2hPBG] were positively associated with elevated blood glucose levels, whereas praseodymium (Pr), thulium (Tm), and lanthanum (La) exhibited negative association. The mixture effect analysis using QGC and BKMR models showed no significant overall impact on GDM and glucose homeostasis. However, the consistency in contribution directions across models aligned with the multivariate regression findings, indicating a coherent pattern. Interaction analyses revealed a significant interaction between Dy and Gd, highlighting the complexity of REE exposure in relation to GDM risk. These bidirectional associations underscore the intricate and multifacedted roles that different REEs may play in glucose metabolic homeostasis during pregnancy.