Open Access Research

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

Michał Kiciński1, Mineke K Viaene2, Elly Den Hond3, Greet Schoeters34, Adrian Covaci5, Alin C Dirtu5, Vera Nelen6, Liesbeth Bruckers7, Kim Croes8, Isabelle Sioen9, Willy Baeyens8, Nicolas Van Larebeke10 and Tim S Nawrot111*

Author Affiliations

1 Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium

2 Department of Neurology, Sint Dimphna Hospital, Geel, Belgium

3 Flemish Institute for Technological Research, Environmental Risk and Health, Mol, Belgium

4 Department of Biomedical sciences, University of Antwerp, Antwerp, Belgium

5 Toxicological Center, University of Antwerp, Antwerp, Belgium

6 Department of Health, Provincial Institute for Hygiene, Antwerp, Belgium

7 Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium

8 Department of Analytical and Environmental Chemistry, Brussels Free University (VUB), Brussels, Belgium

9 Department of Public Health, Ghent University, Ghent, Belgium

10 Department of Radiotherapy and Nuclear Medicine, University Ghent, Ghent, Belgium

11 School of Public Health, Occupational and Environmental Medicine, KULeuven, Leuven, Belgium

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Environmental Health 2012, 11:86  doi:10.1186/1476-069X-11-86

Published: 14 November 2012

Abstract

Background

Animal and in vitro studies demonstrated a neurotoxic potential of brominated flame retardants, a group of chemicals used in many household and commercial products to prevent fire. Although the first reports of detrimental neurobehavioral effects in rodents appeared more than ten years ago, human data are sparse.

Methods

As a part of a biomonitoring program for environmental health surveillance in Flanders, Belgium, we assessed the neurobehavioral function with the Neurobehavioral Evaluation System (NES-3), and collected blood samples in a group of high school students. Cross-sectional data on 515 adolescents (13.6-17 years of age) was available for the analysis. Multiple regression models accounting for potential confounders were used 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. In addition, we investigated the association between brominated flame retardants and serum levels of FT3, FT4, and TSH.

Results

A two-fold increase of the sum of serum PBDE’s 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). The effects of the individual PBDE congeners on the motor speed were consistent. 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 with an 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. We did not observe effects of PBDE’s on neurobehavioral domains other than the motor function. HBCD and TBBPA did not show consistent associations with performance in the neurobehavioral tests.

Conclusions

This study is one of few studies and so far the largest one investigating the neurobehavioral effects of brominated flame retardants in humans. Consistently with experimental animal data, PBDE exposure was associated with changes in the motor function and the serum levels of the thyroid hormones.

Keywords:
Brominated flame retardants; PBDE; TBBPA; HBCD; Neurotoxicity; Neurobehavioral function; Cognitive function; Cognition; Adolescents