12th workshop on Bromitated and other Flame Retardants, Boston, MA, June 5 - 7, 2011.
Summary: Introduction Brominated flame retardants such as the polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) are well known to be present in indoor air and dust and contribute to human exposure. However, the influence of indoor contamination on human body burdens is not fully understood. Some recent studies have suggested that for many individuals indoor exposures may be comparable to or greater than the dietary intake. The aim of this study was to characterize exposure pathways to PBDEs and HBCD and compare exposure estimates with biomonitoring. Materials and Methods A study group of 41 female volunteers from the greater Oslo area, Norway was established. Informed consent was obtained from all the participants and the project was approved by the Regional Committee for Medical Research Ethics. Samples of house dust as well as indoor air from the women¿s residences were collected between February and May 2008. The women also donated serum samples and completed a questionnaire covering demographic information, life style factors as well as dietary habits. PBDEs and HBCD were determined in all samples types. Results and discussion The sum of six tri- to hexa BDEs (BDE-28, 47, 99, 100, 153 and 154) in the women¿s serum ranged from 0.67 to 30 ng/g lipids, while BDE-209 ranged from 0.46 to 11 ng/g lipids. Of these PBDEs, only BDE-28 and 47 were found above LOQ in air, in concentrations ranging from 0.78-58 and 1.3-63 ng/m3, respectively. In addition BDE-66 and BDE-49/71 were occasionally detected. In house dust, the sum 6 PBDEs ranged from 9.3 to 662 ng/g, while the sum of ¿, ß, and ¿-HBCD ranged from 55-2808 ng/g. Individual PBDE congeners were well correlated within each sample type. Significant correlations were also found between individual PBDE concentrations in air and dust as well as between sum 6 PBDE in dust and sum 6 PBDE in serum. Assuming an ingestion of house dust of 50 mg per day, the intake of sum 6 PBDE ranged from 0.008 to 0.47 ng/kg bw/day (mean 0.064 ng/kg bw/day). The corresponding value for sum HBCD was 0.039-2.2 ng/kg bw/day (mean 0.30 ng/kg bw/day). The intake from food has not been assessed in this cohort yet, but ongoing multivariate regression analyses point to statistically significant associations between serum concentrations of PBDEs and some variables in the indoor environment as well as the diet. The dietary intake was estimated to range from 0.14-3.6 ng/kg bw/day (mean 1.1 ng/kg bw/day) for sum 7 PBDEs (sum 6 PBDE + BDE-183) and 0.06-0.87 (mean 0.27 ng/kg bw/day) for sum HBCD in one of our previous studies on persons exposed to background contaminated food in Norway. These preliminary findings suggest that exposure from house dust is important with respect to body burdens of BFRs, HBCD in particular.