Risks Assessment of Copper (Cu), Lead (Pb), Mercury (Hg) and Zinc (Zn): A case study of Tilapia guineensis in Lagos Lagoon

Abstract

This study determined the daily intake of copper (Cu), lead (Pb), zinc (Zn) and mercury (Hg) in order to assess both carcinogenic and non-carcinogenic risks caused by the heavy metals in Tilapia guineensis of Lagos Lagoon. The heavy metals were determined using flame atomic absorption spectrophotometer. The metal distribution was Zn > Cu > Pb > Hg with values of 0.0248±0.04, 0.0093±0.01, 0.0005±0.00 and 0.000±0.00 mg/kg respectively. Daily Intake of Metal was in the order of Zn (0.02) > Cu (0.01) > Pb (0.00) ≥ Hg (0.00), while Target Hazard Quotient decreased in the order of Pb (3.82×10-4) > Cu (9.54×10-5) > Zn (2.49×10-6) > Hg (0.00). The values for Health Risk Index were 0.016 (Cu), 0.00 (Hg), 0.006 (Zn) and 0.034 (Pb), while that for the Health Quotients were 0.400 (Pb), 0.187 (Cu), 0.066 (Zn) and 0.00 (Hg). Similarly, all Hazard Index were less than one. This showed that the consumption of the fish from the study area had no non-carcinogenic health implication of Hg, Zn, Cu and Pb. However, the Target Cancer Risk for Pb (1.38×10-8) indicated minimum cancer risks for the consumers. The ecological risks quotients also revealed that T. guineensis of Lagos Lagoon constituted no ecological risk to the environment since the ERQs were less than one (i.e. ERQ < 1).