Polybrominated diphenyl ethers (PBDEs) in the indoor environment and associations with prenatal exposure

As part of a larger exposure study, samples of dust and indoor air were collected in the homes of 43 pregnant women living in the Copenhagen area (Denmark) and analysed for 12 polybrominated diphenyl ethers using GC-MS. A second dust sample collected after delivery was analysed for BDE-183 and BDE-209, which were highly correlated with the pre-delivery samples, but did not reproduce the actual values. Concentrations as high as 80 μg/g were measured for the dominant BDE congener BDE-209, with median concentrations of 332 and 432 ng/g, respectively, in pre- and post-delivery dust samples. In 12% of the dust samples, the concentration of BDE-209 was lower than that of the summed concentration of PentaBDE congeners. The median concentrations of BDE-47 and BDE-99 in dust were 16.9 and 13.6 ng/g, respectively. The dust concentrations were in line with other European studies and confirmed previously established geographical differences between continental Europe and North America. Additional octa- and nonaBDE congeners (BDE-197, BDE-203, BDE-206, BDE-207, and BDE-208) were analysed in dust and analytical issues were discussed as these congeners also can be a product of thermal degradation of BDE-209 in gas chromatographic analysis. BDE-206 was the dominating nonaBDE, with median and maximum concentrations of 12.8 and 2217 ng/g, respectively, but the ratio of nonaBDEs to the sum of nona- and decaBDEs was relatively constant, despite a large range in absolute dust concentrations. While the congeners of the PentaBDE mixture were highly inter-correlated for both dust and air, no correlation was found with BDE-209 in either matrix. Air concentrations were relatively high in an international context, with median concentrations of 134, 63.7 and 119 pg/m³ for BDE-47, BDE-99 and BDE-209, respectively, and not correlated with dust concentrations. Additional placenta data were available for the study group and found to correlate significantly with dust concentrations for some PentaBDE congeners, but not BDE-209, indicating that dust may be an important exposure pathway for PentaBDE congeners. While BDE-209 also was present in placenta, it did not exceed the other congeners by the same factors as in dust. This might be caused by a combination of the compound's physical-chemical properties affecting bioavailability, uptake, partitioning and metabolisation, and other sources of exposure, but was not investigated further in this study. For all matrices, the PBDE profile resembled that of the technical product Bromkal 70-5DE, but air contained higher percentages of the lower brominated congeners and placenta tissue was dominated by BDE-153. The predominance of BDE-153 has been described in other studies on human samples and related to the highest retention in the body, but further research into toxicokinetics will be required to clarify mechanisms.