Micronucleus Assay and Heavy Metals Characterization of E-waste Dumpsites in Lagos and Osun States, Southwest Nigeria

Jk Igbo,L O Chukwu ,Jt Zelikoff ,E.o Oyewo ,Bl Jason

doi:10.4314/jasem.v22i3.7

Abstract

The contamination of the aquatic ecosystem with heavy metals arising from the discharge of electronic waste (e-waste) or seepage of leachate from open waste dumpsites is on the increase. The impact of e-waste leachate on the micronucleus (MN) of Tilapia guineensis and the levels of heavy metals ( Pb, Cd, Cr, As, Hg, Al and Ba) in the sediments, water, leachate and aquatic fauna ( Tilapia guineensis, Callinectes amnicola and Cardiosoma armatum ) found in and around e-waste dumpsites in Lagos and Osun States was studied. The levels of heavy metals were determined using PyeUnicam model 969 Atomic Absorption Spectrophotometry and Inductive Coupling Plasma Atomic Absorption Spectrophotometry (ICP-AAS).The heavy metal concentrations decreased in the order: Pb ˃ Cd ˃ Cr ˃ Hg ˃ Al ˃Ba ˃As in the samples. The level of Cd in fish muscle from Lagos (1.4mg/kg) exceeded the Environment Canada threshold effect level (EC TEL, 2006) recommended for sea food (1.0mg/kg). The calculated bioconcentration factor (BCF) for fish gills (1.4 and1.0) and fish muscles. (3.6 and 1.2) from Lagos and Osun States respectively as well as the bioaccumulation factor (BAF) for crabs (1.78 and 1.36) are strong indications of the ability of the organisms to bioaccumulate the heavy metals. The MN assay showed an initial increase in the frequency of mionccronuclei on the 7th day which gradually decreased on the 14th and 21st day. The result of this study reveals the toxic impacts of e-waste contamination on ecological and human health in a developing economy.

Highlights

Waste electrical and electronic equipment (WEEE) is composed of approximately 60% metals, 20% organic compounds, and 20% residual materials such as wood or glass (Stankovic et al 2012)
This present study assesses the levels of some heavy metals of interest in e-waste (Hg, As, Pb, Ba, Cd, Cr and Al) in water, sediment, biota and leachate from e-wastes dumpsites in Lagos and Osun States Southwest, Nigeria, determines the genotoxic effect of e-waste on Tilapia guineensis and calculates the bioaccumulation levels of the organisms to sedimentary particles as well as the toxicity posed to the benthic community by these pollutants
Larger volumes of waste were recorded in Lagos than in Osun and this was attributed to a higher density market in Lagos. Both dumpsites are situated in market places that serve as residential areas and it was observed that the waste are constantly burnt in order to reduce the volume

Summary

Introduction

Waste electrical and electronic equipment (WEEE) is composed of approximately 60% metals, 20% organic compounds, and 20% residual materials such as wood or glass (Stankovic et al 2012). The environmental costs of electronics production and consumption are increasingly affecting peripheral ecosystems and could become important drivers of environmental deterioration and biodiversity loss Jang et al, (2011).This is due to the complex mix of environmental pollutants released during recycling and disposal of e-waste which may irreversibly hamper the ecosystems of many developing Countries like Nigeria Toxic heavy metals such as lead (Pb), mercury (Hg), arsenic (As), cadmium (Cd) from e-waste are known carcinogens and when dispersed into the environment contaminate the air, surface and groundwater, sediment, biota and soil. This present study assesses the levels of some heavy metals of interest in e-waste (Hg, As, Pb, Ba, Cd, Cr and Al) in water, sediment, biota and leachate from e-wastes dumpsites in Lagos and Osun States Southwest, Nigeria, determines the genotoxic effect of e-waste on Tilapia guineensis and calculates the bioaccumulation levels of the organisms to sedimentary particles as well as the toxicity posed to the benthic community by these pollutants

Methods

Results

Conclusion