PBDE levels in pooled serum samples of newborns, adolescents and adults from Flanders, Belgium Laurence Roosens 1 , Hugo Neels 1 , Gudrun Koppen 2 , Greet Schoeters 2 , Vera Nelen 3 , Nik van Larebeke 4 , Ronny Blust 5 , Adrian Covaci 1,5 1 Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium 2 Environmental Toxicology, Flemish Institute of Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium 3 Provincial Institute for Hygiene, Kronenburgstraat 45, 2000 Antwerp, Belgium 4 Study Centre for Carcinogenesis and Primary Prevention of Cancer, Department of Radiotherapy, Nuclear Medicine and Experimental Cancerology, University Hospital Ghent, UZ 4K3, Pintelaan 185, 9000 Ghent, Belgium 5 Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium Introduction Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants in polymer materials, textiles, electronic boards and other materials. Due to their widespread use and specific properties, such as high lipophilicity, persistency and bioaccumulative nature, these chemicals have already been detected in humans (Sjödin et al. 2003). They have been shown to possess toxicological potential (Darnerud 2003) and, therefore, their presence in high concentrations can have health consequences, especially for organisms at the top of the food chain, such as humans. The aim of this study was to evaluate the actual contamination levels and profiles of PBDEs in human serum samples from Belgium and to investigate the relationship of PBDEs levels with age, residence area and other contaminants, such as polychlorinated biphenyls (PCBs). Methods and materials Sampling. Serum samples were collected from three different age groups: newborns (cord blood), adolescents and adults and 8 different regions (Table 1). Samples belonging to one age group and one region were pooled. The campaign was approved by the ethical committee of the University of Antwerp. Mothers were enrolled via 25 maternities and adolescents via 42 schools spread over the eight regions. Adults were selected out of community lists and contacted via letter followed by phone call. Inclusion criteria were living for at least 5 years in the area of interest, giving informed consent, being able to fill out Dutch questionnaires and belonging to the age group between 14 and 15 years for the youngsters and between 50 and 65 years old for the adults. The sampling period of the mothers was between October 2002 and December 2003. The adolescents were recruited between October 2003 and July 2004, while the adults were recruited between October 2004 and July 2005. The blood collection methods were tested on contamination and/or adhesion of the measured compounds. After blood sampling, serum was separated by centrifugation within one day in either the maternity, blood bank laboratories or by the field workers in the schools (adolescents) or at local sampling locations installed for the adults (Koppen et al. 2006). All serum samples were kept at +4 °C for maximum one week and, after pooling according to the above described criteria, they were kept at -20 °C until analysis. In total 23 pooled samples (3 age groups x 8 regions, except for one sample not available), 4 procedural blank samples (5 ml water instead of serum) and 1 in-house laboratory reference material serum sample were processed in one batch. The following contaminants were targeted: PBDE