House dust has been recognized as a source of exposure to polybrominated diphenyl ethers (PBDEs), in particular for children . Since the EU ban of the commercial PBDE Penta- and OctaBDE mixtures in 2004 and the regulation of DecaBDE through the EU Restriction of Hazardous Substances (RoHS) Directive, replacements might have been in use . Building on our previous results on PBDEs in house dust from Denmark and associations with perinatal exposure , the present study addresses i) PBDE levels in dust sampled in 2014 in comparison with 2007, ii) the occurrence of alternative flame retardants (aFRs) in samples from both years.
The aFRs studied here included bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE), decabromodiphenyl ethane (DBDPE), 2,3-dibromopropyl-2,4,6-tribromophenyl ether (TBP-DBPE) and dechlorane plus (DDC-CO). Furthermore, hexabromocyclododecane (HBCD) was included although globally banned since 2013.
While TBP-DBPE was below detection limits in several dust samples, the remaining aFRs were detected in all samples from 2007 and 2014. DDC-CO had relatively low concentrations (median < 5 ng/g for each of the isomers). HBCD had the highest concentration (median of 200 ng/g, predominated by -HBCD), followed by DBDPE > BEH-TEBP > BTBPE ~ EH-TBB, based on median values. None of these median concentrations reached the median value of BDE-209 of 432 ng/g obtained in 2007 . As previously observed for PBDEs, distributions were skewed with arithmetic means clearly higher than medians, suggesting that exposure might be much above average for certain individuals. Likewise, the FR composition in dust varied, with individual dust samples containing more BEHT-TEBP or BTBPE than DBDPE.
The large variation in the data prevents 2007 and 2014 data from being significantly different, but there are indications of higher concentrations of DBDPE, BEH-TEBP and EH-TBB in 2014 than in 2007. While BDE-209 remained unchanged from 2007 to 2014, BDE-47 appeared lower in the 2014 samples. Similar developments have been reported from the USA . BDE-209 and DBDPE were found to be correlated in the dust samples, which might reflect similar use patterns. Future work will focus on the significance of the occurrence of these compounds in dust for questions of human exposure.
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