Neurobehavioral function and low-level exposure to brominated flame retardants in adolescents: A cross-sectional study

Animal and in vitro studies demonstrated a neurotoxic potential of brominated flame retardants. The aim of this study was to investigate the associations between biomarkers of internal exposure to brominated flame retardants [serum levels of polybrominated diphenyl ether (PBDE) congeners 47, 99, 100, 153, 209, hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA)] and cognitive performance. We assessed the neurobehavioral function using the Neurobehavioral Evaluation System (NES-3) battery of tests and analyzed blood samples of high school students. Cross-sectional data on 515 adolescents (13.6–17 years of age) was available for the analysis. A two-fold increase of the sum of serum PBDEs was associated with a decrease of the number of taps with the preferred-hand in the Finger Tapping test by 5.31 (95% CI: 0.56 to 10.05, p = 0.029). Serum levels above the level of quantification were associated with an average decrease of FT3 level by 0.18 pg/mL (95% CI: 0.03 to 0.34, p = 0.020) for PBDE-99 and by 0.15 pg/mL (95% CI: 0.004 to 0.29, p = 0.045) for PBDE-100, compared with concentrations below the level of quantification. PBDE-47 level above the level of quantification was associated withan average increase of TSH levels by 10.1% (95% CI: 0.8% to 20.2%, p = 0.033), compared with concentrations below the level of quantification. HBCD and TBBPA did not show consistent associations with performance in the neurobehavioral tests. To conclude, consistently with experimental animal data, PBDE exposure was associated with changes in the motor function and the serum levels of the thyroid hormones.