Size distribution of particle-associated polybrominated diphenyl ethers (PBDEs) and their implications for health

In order to better understand the size distribution of particle-associated PBDEs and their deposition pattern in the human respiratory tract, we carried out a 1-year campaign during 2012–2013 for the measurement of sizeresolved particles at the urban site of Shanghai. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increases, accumulation-mode peak intensity increased while coarsemode peak intensity decreased. This change was consistent with the variation of PBDEs’ subcooled vapor pressure. Absorption and adsorption processes dominated the distribution of PBDEs among the different size particles. The evaluated deposition flux of 613 PBDEs was 26.8 pg h, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine-mode particles contributed major PBDEs in the alveoli region. In association with the fact that fine particles can penetrate deeper into the respiratory system, fine-particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.