Polychlorinated biphenyls in settled dust from informal electronic waste recycling workshops and nearby highways in urban centers and suburban industrial roadsides of Chennai city, India: Levels, congener profiles and exposure assessment.

Polychlorinated biphenyls (PCBs) were quantified in settled dust collected from informal electronic waste (e-waste) recycling workshops and nearby highways in the urban centers and roadside dust from the suburban industrial belt of Chennai city in India. Further dust samples were subjected to a high resolution field emission scanning electron microscope equipped with an energy dispersive X-ray spectrometer (FESEM/EDX) to characterize the shape, size and elemental composition of the dust particles. Geomean of total PCB concentration followed the following order: informal e-waste metal recovery workshops (53ngg)>e-waste dismantling sites (3.6ngg)>nearby highways (1.7ngg)>suburban industrial roadsides (1.6ngg). In e-waste workshops, tetra, penta and hexa-PCB homologs contributed two third of ΣPCB concentration. Informal e-waste recycling workshops contributed more than 80% concentration of all the PCB congeners loaded in the first principal component. Predominance of dioxin like PCBs, PCB-l14, -118 and -126 in the e-waste metal recovery sites were presumably due to combustion and pyrolytic processes performed during recycling of electrical components. According to the morphology and elemental composition, settled dust from e-waste workshops were irregular particles heavily embedded with toxic metals and industrial roadside dust were distinct angular particles. FESEM revealed that average particle size (in Ferret diameter) increased in the following order: e-waste recycling workshops (0.5μm)<nearby highways (1.2μm)<industrial sites (4.3μm). Electronic waste recycling workshops engaged in metal recovery were found with maximum toxicity equivalents (TEQs) for dl-PCBs and potential cancer risk (10-10) for both adult and children.