Size-resolved particle measurements of polybrominated diphenyl ethers indoors: Implications for sources and human exposure

Polybrominated diphenyl ethers (PBDEs) are flame retardant polymer additives that are widely detected in outdoor and indoor environments. Release of PBDEs from consumer products leads to high concentrations indoors, but mechanisms of release are poorly understood. While ingestion of dust is a well-studied indoor PBDE exposure route, the importance of inhalation exposure is uncertain. To address these unknowns, dust was collected from household vacuum cleaners, and suspended particulate matter (PM) was collected from the same homes in St. John’s, Canada using a cascade impactor. Size-fractionated PM samples (0.01-18 µm diameter) were analysed for PBDEs. The sum of PBDEs in all PM ranged from 8.7 ± 0.5 to 15.7 ± 0.5 pg/m3, with >50% of PBDE mass in respirable PM (<1 µm). Mass loadings as a function of particle size suggested both abrasion and off-gassing led to the presence of PBDEs in PM. Variability in the PM mass loadings indicated emission mechanisms were both product- and location-dependent. Congener profiles in co-located vacuum dust and PM samples were different, indicating vacuum dust cannot accurately predict PBDE congeners in respirable PM. A calculated lower limit inhalation exposure to PBDEs (0.19 ng/day) is lower than exposure via diet or ingestion of dust, although the different biochemical pathways for inhalation compared to ingestion may have biological effects. This work highlights the importance of contaminant analysis in size-fractionated PM to assess human exposure via inhalation compared to traditional vacuum dust methods.