Potentially toxic elements pose a threat to environmental quality and human health: The Kumasi Abattoir Ghana in perspective

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The environmental and human health risks of potentially toxic elements (PTEs) – iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), lead (Pb), nickel (Ni), and cadmium (Cd), in the Kumasi Abattoir Ghana (KAG) untreated effluent have been investigated. PTEs' spatial variability was analyzed using principal component analysis (PCA). Environmental risk assessments were investigated using three novel indices Effluent Pollution Index (EPI), Effluent Discharge Quality Index (EDQI), and modified Heavy Metal Pollution Index (mHPI), which incorporated eigenvectors from the two PCs. Carcinogenic and non-carcinogenic health risks were evaluated for children and adults using standard methods. The high signal-to-noise ratio (SNR) in the PCA was attributed to PC1 (54.2 %) and PC2 (26.2 %), accounting for 80.4 % of the total variance. The eigenvectors of Cu and Zn (both non-carcinogenic) for PC1 and Mn (non-carcinogenic) and Pb (carcinogenic and non-carcinogenic) for PC2 exerted the most effects. PC1 and PC2 corresponded to the effluent temperature and chemical oxygen demand (COD), respectively. The highest EPIpc1 = 61.20 and EPIpc2 = 46.48 were attributed to Fe. Ni had the lowest values (EPIpc1 = 0.02, EPIpc2 = 0.01). EDQIpc1 = 9.52, EDQIpc2 = 7.30 and mHPIpc1 = 474.97 and mHPIpc2 = 267.94 depicted major environmental threats. These indices corresponded to the effluent nitrate (NO3−). Major health threats emerge through ingestion non-carcinogenic (child = 31.42; adult = 18.88) and carcinogenic risk (child = 8.25 × 10−1; adult = 4.96 × 10−1). The dermal health risks were negligible non-carcinogenic (child = 6.25 × 10−4; adult = 3.91 × 10−4) and carcinogenic (child = 1.36 × 10−6; adult = 8.52 × 10−7). Limited by national exposure values, this study provides scientific evidence of potential dangers associated with PTE exposure in the KAG's effluent. It also serves as a critical bridge between environmental quality and health risk of vulnerable communities, calling for actionable intervention.