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

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 7 th day which gradually decreased on the 14 th and 21 st day. The result of this study reveals the toxic impacts of e-waste contamination on ecological and human health in a developing economy.

Public Health Burden of E-waste in Africa

“…Toxic and genotoxic levels can induce adverse ecological and human health effects. 16,39 Soil leachate and well water samples from the Alaba international and Computer village electronic markets in Lagos State, Nigeria showed both mutagenic and genotoxic properties in plant and animal models. 16,24,25,[40][41][42] Exposure of T. guineensis juveniles to varying concentrations of e-waste leachate could be genotoxic to fish.…”

“…16,24,25,[40][41][42] Exposure of T. guineensis juveniles to varying concentrations of e-waste leachate could be genotoxic to fish. 39 Hazardous heavy metals such as As, Cd, Hg, Pb from e-waste are known to cause cancer. 43 In their study "Perceived public health effects of occupational and residential exposure to electronic wastes in Lagos, Nigeria" the authors reported cases of cancer among e-waste workers who had spent at least 6 years or more in e-waste sites.…”

Assessment of Micronucleation and Abnormal Nucleation in the Peripheral Erythrocytes of the Fish Mystus gulio of Hooghly River Downstream as per Seasonal Variation

“…Various researchers found that metal bioaccumulation in fish organs causes genotoxic consequences such as DNA damage, MN, Nas, etc. (Omar et al, 2012;Nagpure et al, 2015;Igbo et al, 2018). According to Hussain et al (2018), fish genotoxicity is a genotoxic indicator, and blood is a useful biomarker for assessing the risk of water pollution and genotoxin.…”