Novel and legacy brominated flame retardants in human breast milk and house dust from Denmark

A suite of novel brominated flame retardants (NBFRs), hexabromocyclododecanes (HBCDDs), polybrominated diphenyl ethers (PBDEs) and dechlorane plus were measured in matched samples of house dust (n = 47) and human breast milk (n = 40) from Denmark sampled in 2007, i.e., shortly after PBDE restrictions were implemented in Europe providing a valuable reference point. The most abundant BFR in breast milk was BDE-153 with a median concentration of 0.79 ng/g lipid followed by BDE-47 (median: 0.61 ng/g lipid) and BDE-209 (median: 0.53 ng/g lipid). Levels of bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP) were comparable (median: 0.78 ng/g lipid); however, they were based on fewer samples. α-HBCDD was the most abundant HBCDD in breast milk (median: 0.24 ng/g lipid) and detected in all samples. The house dust samples were dominated by BDE-209 (median: 432 ng/g) and γ-HBCDD (median: 177 ng/g); among the NBFRs, the highest levels were found for decabromodiphenyl ethane (DBDPE) (median: 86.2 ng/g) and BEH-TEBP (median: 26.7 ng/g). BDE-28, 47 and 153 were significantly correlated between breast milk and serum (rs = 0.73-0.81, P < 0.0001); however, this was not the case for any of the NBFRs. Intake estimates for a 3-month-old infant indicated that for most of the flame retardants, breast milk was by far the dominant route of exposure, whereas dust only contributed substantially for BDE-209, γ-HBCDD, and to some extent α-HBCDD. This study is the first to report on human exposure to NBFRs in Denmark and shows that internal exposure levels of NBFRs were similar to those of most PBDEs already at the time of PBDE restrictions.