Changes in metal contamination related to the evolution of electronic technologies

Abstract Proper management of electronic waste (e-waste) represents significant economic and environmental challenges because of the tremendous quantity of e-waste, the potential of extracting precious metals from recyclable electronics, and the risks of environmental contamination from a variety of toxic compounds. This study focused on the leaching potential of 57 elements from central processing unit mainboards of different periods (1980s to 2010s) using river water at different pHs as an environmentally-relevant extractant. The exposure time was set to one week. The calculated contamination factors allowed classification of the elements released from mainboards into five groups with increasing leachability and thus environmental concerns. Also, the results demonstrated a changing nature of e-waste related to the technologies employed and the transition of metal contamination signatures from these electronics; newer computer mainboards have a lower risk of Pb and Sn leaching but a more significant release of Li, Sb, and a few rare earth elements (Sm, Eu, Dy). These specific patterns of elemental release could be powerful geochemical forensic tracers of improper recycling activities of e-waste in the environment. Most studies until now have investigated just a few key contaminants, despite a cocktail of pollutants contained in electronics. Therefore, a full assessment of the leaching potential of metal pollutants from non-properly recycled e-waste and further ecotoxicological studies of this cocktail of contaminants are timely needed.