RESUMEN
Although there is rising global concern over the environmental, ecological, and human health risks associated with the discharge of leachates from e-waste dumpsites into the aquatic ecosystems, little is known in this research area. Thus, for this study, we first defined the chemistry of the test leachate, followed by assessment of the leachate on the development of a model aquatic organism (Fundulus heteroclitus) used extensively as a bioassay organism in pollution studies. Chemical analyses revealed that levels of phosphate (20.03 mg/L), cadmium (Cd) (0.4 mg/L), lead (Pb) (0.2 mg/L), and chromium (Cr) (0.4 mg/L) were higher than the 2009 US EPA and the 2009 National Environmental Standards and Regulations Enforcement Agency (NESREA) permissible limits. Polycyclic aromatic hydrocarbon (PAH) burdens were dominated mainly by the high molecular weight congeners, specifically the ∑4rings (73 µg/L). Total polychlorinated biphenyls (PCB) levels ranged from 0.00 to 0.40 µg/L with the ∑deca PCBs reaching the highest concentration. For the biological studies, F. heteroclitus embryos (48-h post-fertilization) were divided randomly into groups and exposed to one of six e-waste leachate concentrations (10, 1, 0.1, 0.01, 0.001, 0.0001%). Significant differences (p ≤ 0.05) between treated and control groups were observed in standard and total length, and head size. Further analysis using Duncan's post-hoc test of multiple comparison also revealed specific differences within and between specific treatment groups. We conclude that e-waste leachate arising from indiscriminate dumping into aquatic ecosystems in Nigeria contains mixtures of toxic constituents that can threaten ecosystem and public health.
RESUMEN
This study assesses arsenic (As) fractionation in sediments and speciation in muscle tissues of Bagrid catfish, Chrysichthys nigrodigitatus from Lagos Lagoon, southwest Nigeria to determine risks to ecological receptors and humans. Residual As was the predominant geochemical fraction (86.2%) in sediments. Arsenite [As (III)] concentrations which ranged from 0.06 to 0.53 mg kg-1 in catfish muscle tissue, accounting for 25.9% of total As was the dominant species. Less toxic dimethylarsinic acid (DMA) which varied between 0.06 and 0.27 mg kg-1 made up to 10.8% of total As in catfish muscle tissue. Estimated human average daily intake (ADI) of As as As (III) and DMA were 1.35 × 10-4 and 0.62 × 10-4 mg kg-1 BW with corresponding hazard quotients (HQs) of 0.45 and 0.21, respectively, indicate no apparent health hazard to adult consumers. The incremental lifetime cancer risks (ILCR) of 0.78 × 10-3 for total As, 0.20 × 10-3 for As (III), and 0.93 × 10-3 for DMA, for adults from the consumption of catfish is slightly higher than the US EPA threshold and indicates moderate carcinogenic risk. Furthermore, 12.5% bioavailable fraction of As in sediment and relatively higher levels of As (III) in fish tissues has ecological and public health implications.