Evaluation of toxic metals in plastic components of discarded mobile phones commonly used in Nigeria

Abstract

This study investigates the concentration of selected toxic metals in the waste plastic components of discarded mobile phones from five major brands commonly used in Nigeria, focusing on their environmental and health implications. Twenty-five mobile phones across five brands were collected from repairers in Uyo, Akwa Ibom State Nigeria, and disassembled into major components (printed wiring boards (PWBs), liquid crystal displays (LCDs), and plastics). Plastic components were shredded to enable analysis, and samples were analyzed in their unwashed state to reflect real-world contamination. Concentrations of toxic metals specifically silver (Ag), cadmium (Cd), nickel (Ni), and lead (Pb) were measured using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The results reveal heterogeneity and unexpectedly high Ni levels in certain samples, emphasizing the complexity and challenges of accurately characterizing metals in mixed plastic matrices and the influence of disassembly/handling on surface contamination. Across all brands, mean concentrations (mg/kg) were Ag 9.2 ± 1.9; Cd 46.2 ± 12.5; Ni 738 ± 1072; Pb 62.4 ± 32.0. ANOVA indicated significant inter-brand differences for Ag, Ni, and Pb, with Ni and Pb showing strong brand-related variation, and brand C and brand E often stand out. Comparison with total threshold limit concentration (TTLC) standards showed all metals were generally below limits, except Ni in brand C samples. This suggests the materials may not pose an immediate risk under typical disposal. However, potential metal release through leaching, especially in landfill or incineration scenarios, remains a concern. The data support the need for improved end-of-life management and formal recycling to mitigate long-term ecological impacts.