Assessing the implications of export of waste electrical and electronic equipment (WEEE) towards developing regions: PCBs as a case study

Densely populated areas (i.e., urban centres) are
largely responsible for the generation of waste electrical and Electronic equipment (WEEE/e-waste) in both industrialized and developing nations. The potential emission of both emerging and Legacy contaminants present in WEEE (e.g., organic chemicals, metals) during handling and disposal of these products is a concern with impacts at
local to global scale. Over the last decade, a number of studies have reported surprisingly high levels of polychlorinated biphenyls (PCBs) within or outside developing regions in Asia and West Africa. As PCBs
were never extensively produced nor used in these regions, this previously led us to hypothesize that there might be a potential shift in global source regions, attributed to exports of wastes containing PCBs towards developing regions. If true, it follows that global emissions,
transport and exposures can neither be completely estimated, nor fully rationalized, without considering emissions caused by the global flows of relevant wastes. In this study, we have therefore updated an existing global historical PCB emission inventory to account for exports of wastes, using global flows of e-waste as a proxy for wastes containing
PCBs. Our revised emission scenarios indicate that (i) global emissions may significantly increase as result of exports of wastes in comparison to reference scenario (i.e. no exports) and (ii) different long-term temporal trends in emissions within former production and use regions versus developing regions implicated as importers of wastes are
expected. The second goal of this study is to simulate the global fate and transport of PCBs using emission scenarios that include potential contributions linked to the export of e-waste and compare model output to the baseline scenario (no export). To accomplish this task, we use the BETR Global 2.0 model, a publicly available fate/transport model, which represents the globe as 288 interconnected, multi-compartment
zones at a spatial resolution of 15 x 15 degrees. Simulations are conducted for the period 1930–2100 and output from various locations and time periods are interpreted in the context of available monitoring
data. Model output is also used to assess the potential implications of transboundary movement of wastes containing PCBs for human exposure in developing regions. However, significant uncertainties in these global emission scenarios still persist.