Study on human exposure and metabolic excretion mechanism of decabromobiphenyl based on biological monitoring and molecular docking

This study systematically evaluated the exposure characteristics and human metabolic excretion mechanisms of decabromobiphenyl (BB-209) by integrating environmental monitoring and molecular docking techniques. The results showed that BB- 209 was predominant in dormitory dust, accounting for 91% of the total polybrominated biphenyls with a median concentration of 0.857ng/g. In hair samples, BB-209 was the major accumulated congener (maximum concentration: 16.04ng/g), and no significant difference was observed across different living environments, indicating ongoing exposure. Urine analysis revealed increased excretion of the low-brominated congener 4,4'-dibromobiphenyl (BB-15), whereas BB-209 excretion was limited due to its strong binding energy with Megalin (-6.76 kcal/mol). Molecular docking results demonstrated that BB-209 has a weaker binding affinity to CYP450 enzymes than 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), with binding free energies of -6.79 kcal/mol and -7.27 kcal/mol, respectively, confirming its metabolic inertness. Compared with banned analogous pollutants, BB-209 exhibited significantly higher residual levels in dust than decachlorobiphenyl (PCB-209), and its accumulation in hair reached 21% of that of decabromodiphenyl ether (BDE-209). Currently, BB-209 has not been included in the Stockholm Convention on Persistent Organic Pollutants (Stockholm Convention)or China's List of Key Controlled New Pollutants. This study recommends hair monitoring as an effective tool for assessing BB-209 exposure and calls for enhanced differentiation of polybrominated biphenyl congeners in electronic products, thereby providing a scientific basis for controlling the health risks posed by BB-209 to humans.