Occurrence of hexabromocyclododecanes (HBCDs) and tetrabromobisphenol A (TBBPA) in indoor dust from different microenvironments: levels, profiles, and human exposure

The levels and distributions of hexabromocyclododecane diastereoisomers (HBCDs) (including alpha, beta, and gamma-HBCD) and tetrabromobisphenol A (TBBPA) were investigated in indoor dust from bedrooms and offices. HBCDs diastereoisomers were the most abundant compounds in the dust samples, and the concentrations of n-ary sumation HBCDs in the bedrooms and offices ranged from 10.6 to 290.1 ng/g and 17.6 to 1521.9 ng/g, respectively. The concentrations of target compounds in the offices were generally higher than those in the bedrooms, probably due to the presence of more electrical equipment in the offices. In this study, highest levels of target compounds were all found in the electronics. In the bedrooms, the highest mean level of n-ary sumation HBCDs was found in air conditioning filter dust (118.57 ng/g), while the personal computer table surface dust showed the peak mean concentrations of n-ary sumation HBCDs (290.74 ng/g) and TBBPA (539.69 ng/g) in the offices. Interestingly, a significantly positive correlation was observed between the concentrations of n-ary sumation HBCDs in windowsills and beddings dust in the bedrooms, suggesting beddings was one of the crucial sources of n-ary sumation HBCDs in the bedrooms. The high dust ingestion values of n-ary sumation HBCDs and TBBPA were 0.046 and 0.086 ng/kg bw/day for adults, while 0.811 and 0.04 ng/kg bw/day for toddlers, respectively. The high dermal exposure values of n-ary sumation HBCDs were 0.026 and 0.226 ng/kg bw/day for adults and toddlers, respectively. Except for dust ingestion, other human exposure pathways (such as the dermal contact with beddings and furniture) should be paid attention.