Health risk assessment and bioaccumulation of heavy metals in leafy vegetables irrigated with wastewater in Zawaciki, Kano State, Nigeria
Abubakar Mohd Habu, Ali Sanusi Hassan, Adeniyi Olarewaju Adeleye, Michael Edet Nkereuwem, Ijanu Emmanuel Madu, Garba Barde Bate, Olukemi Adeleye, Usman Mohammed Isah
Biological Environment and Pollution
Urban Farm DB summary
This study assessed heavy-metal accumulation and non-carcinogenic health risks in commonly consumed leafy vegetables -- lettuce, spinach, and cabbage -- cultivated with wastewater in Zawaciki, Kano State, Nigeria. Vegetable and rhizospheric soil samples were analyzed for cadmium, lead, chromium, nickel, zinc, and copper using atomic absorption spectrophotometry, and bioaccumulation factors (BAFs) were calculated as the ratio of metal levels in plant tissue to soil. Metal concentrations varied significantly across the vegetables (p < 0.05), with lead in lettuce leaves exceeding the FAO/WHO permissible limit by more than 120 times; chromium in cabbage reached 32.22 mg/kg, while lettuce showed elevated zinc (19.83 mg/kg) and copper (9.26 mg/kg). Hazard-quotient risk assessments found HQs for chromium and lead both exceeding 1, and the cumulative hazard index exceeded 1 for all vegetables, reaching its highest value of 18.861 in lettuce.