Ecotoxicological Evaluations of Saw-Milling Activities

Ecotoxicological Evaluations of Saw-Milling Activities

Human Health Risks Perception and In Situ Ecotoxicological Evaluations of Saw-Milling Activities on the Lagos lagoon, Nigeria Using Tilapia and Blue Crab


1*Sogbanmu, T.  O. and 2Ogunkoya, O. A.

1,2Ecotoxicology and Conservation Unit, Department of Zoology, Faculty of Science, University of Lagos, Akoka 101017, Lagos, Nigeria.

*Participating/Corresponding Author Email:



The Okobaba waterfront of the Lagos lagoon, Lagos, Nigeria is exposed to several forms of pollution as a result of wastes generated and discharged from saw-milling activities around the area. The aim of the study was to evaluate the human health risks perception and biological effects of these saw-milling activities on aquatic organisms in the lagoon. The methods utilised for the study were administration of structured human health risks questionnaires to 200 stakeholders in the area, physico-chemical analyses of water and sediment samples as well as in situ toxicity studies to evaluate biochemical and histological effects in Tilapia guineensis (Guinean Tilapia) and Callinectes amnicola (Blue Crab) deployed at the test site over a period of 28 days. The results revealed that saw dusts contribute to 84% of the wastes, 92% of which is burnt and run-off into the lagoon, air quality is highly impacted by the saw-milling activities, symptoms often experienced by respondents were headaches (53%) and skin irritations (28%). Most of the physico-chemical parameters were higher than set limits. Polycyclic aromatic hydrocarbons (PAHs) levels in water and sediments at the test site were significantly different (p<0.05) from the control site. In situ studies showed significant differences (p<0.05) in the concentrations of antioxidant enzymes in the liver and gills of Tilapia guineensis after 28 days compared to control. Histological alterations were observed in the liver cells of T. guineensis only over the study period. The results demonstrate the perception of human health risks by stakeholders working and living around the test site particularly due to the poor air quality from the burning activities and the adverse effects of the saw-mill activities on sensitive fish like T. guineensis. We recommend further empirical studies on the molecular basis and mechanisms of toxicity in exposed animals and humans using genomics tools.


Keywords: Biomarkers, in situ studies, Lagos lagoon, Human health risks perception, Tilapia guineensis, Callinectes amnicola


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