LAUSR

Informal recycling of electronic waste (e-waste) contaminates local environments with metals and other organic compounds, though adverse effects on native earthworm populations are poorly understood. The objective of this study was to determine metal concentrations in soils from e-waste activity sites in Douala (Cameroon), and assess effects of these soils on the growth and reproduction of the local earthworm, Alma nilotica. Concentrations of nine (9) metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were measured in soil samples collected from eight (8) e-waste activity and two (2) non-e-waste sites. Earthworms were then exposed to these soils in the laboratory following OECD test guidelines. Metal concentrations in the e-waste-contaminated soils were significantly higher than in the non-e-waste soils. E-waste soils were found to have a different soil metal profile (Cu > Pb > Zn > Cr > Ni > Co > As > Cd > Hg) from that of the non-e-waste soils (Zn > Cr > Cu > Pb > Ni > As > Cd > Co > Hg). Earthworm growth and reproduction were significantly inhibited in organisms exposed to soils from e-waste sites. Reproduction was particularly affected with a mean of 8 ± 5.6 offspring per 10 worms in the e-waste-exposed worm groups compared to 90.5 ± 0.7 in non-e-waste soil worms. Notably, earthworm growth recovered during depuration in clean soil, indicating the possibility of remediation activities. This study demonstrates that soils at e-waste sites can affect the health of resident worm populations, which may be more sensitive than temperate species. It also highlights the potential of a bioassay-based approach in monitoring risks at e-waste sites. This article is protected by copyright. All rights reserved.