Assessment of ambient polycyclic aromatic hydrocarbons in Egbedi dumpsite in Osogbo, Nigeria

Abstract

The open burning system of municipal solid waste (MSW) disposal releases varying concentrations of emissions into the atmosphere. One of such, Polycyclic Aromatic Hydrocarbons (PAHs) in the atmosphere have been documented to be a threat to humans. This study assessed the concentration of the ambient air PAHs in a MSW dumpsite at Egbedi, Osun State. A polyurethane foam (PUF) passive sampler was installed in 10 locations for 28 days to trap PAHs. The PAH results were subjected to a toxicity equivalence (TEQ), sources were identified by employing the existing diagnostic ratios, and inhalation dosage was investigated using the Excess Lifetime Cancer Risk Assessment (ELCR). The summation of the carcinogenic PAHs and the highest toxicity equivalence for rain and dry seasons were 0.241 µg/m3 and 0.369 µg/m3, and 0.070 and 0.110, respectively. The analysis revealed that the PAHs were mainly from the combustion of MSW. The ELCR values were (9.1 × 10–4) and (5.8 × 10–4), which were above the acceptable carcinogenic risk level of 1.0 × 10–6. The concentration of PAHs released is at a carcinogenic level and the TEQ and diagnostic ratio show that the emission source is from certain wastes. The PCA score plot showed a single cluster that was close to the center, indicating that the burning of MSW was the only source of emissions from the study location that added to the majority of the PAHs in the surrounding atmosphere. There is an urgent need to develop the dumpsite into a standard landfill.