Health risk assessment of some heavy metals in fruits, leaves and roots of Mangifera indica and Psidium guajava around NILEST tannery, Samaru, Zaria, Nigeria. ⃰

Abstract

Industrial tannery operations release hazardous heavy metals into surrounding ecosystems, posing significant risks to food safety and public health. This study conducted a health risk assessment  of copper (Cu), cadmium (Cd), lead (Pb), chromium (Cr), arsenic (As), and cobalt (Co) concentration in fruits, leaves, and roots of mango (Mangifera indica) and guava (Psidium guajava) collected from three locations around the Nigerian Institute of Leather and Science Technology (NILEST) tannery in Samaru, Zaria, Nigeria. Samples were digested using acid mixture (H₂SO₄:HClO₄:HNO₃, 1:2:8 v/v) and analyzed by atomic absorption spectrophotometry. Results showed significantly higher (p < 0.05) metal concentrations at the NILEST site compared to other locations. Guava accumulated consistently higher metal levels than mango across all sites. Cadmium and chromium concentrations exceeded WHO/FAO permissible limits in all samples, with maximum Cd (4.56 ± 1.76 mg/kg) and Cr (11.83 ± 2.46 mg/kg) recorded in guava from the tannery site. Contamination factor analysis revealed extreme cadmium pollution (CF > 6) at NILEST, while geo-accumulation indices indicated moderate to extreme contamination for cadmium. Pollution load indices remained below 1.0 across all locations, suggesting overall low pollution loads despite localized metal enrichment. These findings demonstrate that tannery effluents significantly contaminate nearby fruit crops, with species-specific accumulation patterns indicating guava as a potential bioindicator for heavy metal pollution. Regular monitoring and remediation strategies are urgently needed to protect consumer health.