Sources of halogenated brominated retardants in house dust in an industrial city in southern China and associated human exposure.

Halogenated flame retardants (HFRs) are a class of ubiquitous pollutants in the environment and attract increasing attention. In the present study, HFR concentrations were measured in indoor and outdoor dust in an important industrial city (Dongguan) in southern China, in which their presence and associated human exposure are unknown. The HFRs were dominated by polybrominated diphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE), with mean concentrations of 2365 and 2441 ng/g in the indoor dust, respectively, which were 2-3 order of magnitude higher the concentrations of other HFRs. However elevated tri- to hepta-BDE concentrations (869 ng/g) were found in Houjie Town, a furniture manufacturing center. The mean indoor/outdoor (I/O) ratios of HFR concentrations in the dust were all larger than one (1.55-16.4), suggesting the importance of indoors sources for HFRs in indoor dust in this industrial city. Principal component analysis (PCA) showed that the correlations among the HFRs in the indoor dust probably revealed differences in their commercial applications, while most HFRs in the outdoor dust have similar sources except for phased-out BDE47 and 99. The compositions of lower brominated PBDEs varied among the towns, probably due to their different sources or influence of photo-degradation. Nevertheless, the similar composition of highly brominated congeners indicated little photo-degradation encountered in the ambient environment. The non-cancer risk associated with indoor dust ingestion is low for the general population in Dongguan, but some children in the furniture manufacturing center have significantly high risk of exposure to banned PBDEs.