Polybrominated diphenyl ethers (PBDEs) exposure in elderly agro-pastoralists of Inner Mongolia: Ethnic disparities,...

This study investigated polybrominated diphenyl ethers (PBDEs) exposure and health associations among elderly agro-pastoralists from the Ordos grasslands of Inner Mongolia, China. Serum samples from 77 participants (aged ≥ 64 years; 30 Mongolian, 47 Han) were analyzed for 11 PBDE congeners. Results revealed ubiquitous contamination in all serum samples, with ∑₁₁PBDEs ranging from 0.49 to 898 ng/g lipid weight (median: 21.2 ng/g lw). BDE-209 was the dominant congener (max: 888 ng/g lw), followed by Penta-BDEs (BDE-99, -100). Ethnic disparities were significant: Mongolians exhibited higher ∑₁₁PBDEs (median: 54.6 ng/g lw) than Han participants (median: 17.4 ng/g lw) (p < 0.05), which may be related to meat/dairy-rich diets and potential forage/pasture contamination. Sex and BMI showed no significant differences in overall PBDEs levels, though BDE-183 positively correlated with BMI in females (p < 0.05). Biochemically, Mongolians had elevated low-density lipoprotein cholesterol (LDL-C) (p < 0.05) but lower high-density lipoprotein cholesterol (HDL-C) and glucose (p < 0.05) versus Han participants. Multivariate regression identified BDE-99 as a key biomarker, inversely associated with triglycerides (TG) after adjustment for demographic covariates (age, sex, ethnicity, BMI) (β = -0.087, p < 0.05). PBDEs may contribute to shifts in inflammatory response patterns (e.g., BDE-99 linked to neutrophils; BDE-183 to monocytes) only in metabolically dysfunctional individuals (hyperglycemia/hyperlipidemia). Findings suggest that BDE-99 may serve as a potential indicator of lipid disruption and immune dysregulation, and highlight dietary exposure and metabolic health as possible modifiers of PBDE toxicity in vulnerable populations.