Global review of PCBs and chemical flame retardants in e-waste recycling sites: Addressing geographic imbalances

Informal e-waste recycling poses substantial environmental and human health risks due to contamination by flame retardants (FRs) and related chemical additives. This study systematically reviews the status of research on polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organophosphate esters (OPEs) in e-waste recycling sites, with a particular focus on concentration levels and geographic disparities in data availability. Only a few studies have been conducted in Africa and South America and there are significant gaps. This geographic imbalance and other factors impede accurate assessment and comprehensive understanding of global e-waste pollution and associated risks. In examining the concentrations of PCBs and FRs, the study finds notable variations across different countries. For instance, high levels of these toxic chemicals were reported in China and India, which are major hubs for e-waste recycling in Asia. Concentrations in these regions often exceed international safety standards, posing severe risks for workers and local communities. Conversely, data from Africa and South America are sparse, despite the growing presence of informal e-waste recycling activities in these continents. Factors driving these differences include the prevalence of informal recycling practices, variations in waste import volumes, regulatory gaps, and disparities in technological capacity for safe waste management. In developing countries, weaker enforcement of environmental laws and reliance on rudimentary recycling methods lead to higher levels of contamination. However, developed nations with stricter regulations and advanced technologies exhibit lower concentrations of these pollutants. While high concentrations of FRs are documented in environmental matrices, human biomonitoring and epidemiological studies are needed to correlate environmental concentrations with health outcomes, particularly for workers at e-waste sites. In summary, this review emphasizes the critical need for broader geographical coverage, standardized methodologies, and robust regulatory frameworks to mitigate the significant health and environmental risks associated with FRs and PCBs in e-waste recycling sites.