Exposure assessment and distribution of polychlorinated biphenyls (PCBs) contained in indoor and outdoor dusts and the impacts of particle size and bioaccessibility

The size fraction, bioaccessibility and associated human daily intake of PCBs via indoor and outdoor dust collected from two most populated urban centers of Pearl River Delta (PRD), China, were studied. The σPCBs levels (ngg^-1) in indoor (51.9-264) and outdoor (4.02-228) dust in Guangzhou (GZ) were found higher than those in indoor (17.4-137) and outdoor (7.75-114) dust of Hong Kong (HK). Hexa-PCB was the largest contributor in dust samples (29-64%), followed by tri-PCB. The size fraction of PCBs indicated a high accumulation effect of particles less than 63μm, while the lowest was found in 280-2000μm. Toxic equivalency (TEQ) of dioxin-like PCBs in indoor dust of GZ and HK was 2 to 13 times higher than that in outdoor dust. The bioaccessibility of PCBs was determined as 5-61% depending on individual PCB congeners under study and bioaccessible PCB exposure was significantly lower than the estimate for total PCB. The daily intake of bioaccessible PCBs via dust ranged in 0.02-8.95 and 0.37-17.8ngday^-1 in GZ while 0.01-4.95 and 0.16-9.83ngday^-1 in HK for adults and children, respectively. Dust ingestion contributed to 0.49-10.6% of overall non-dietary PCB exposure (dust ingestion and inhalation) for adults while 12.9-35% for children, indicating the dominant contribution from inhalation.