Immediate and Residual Haematotoxicity in Mice Exposed to Wastewater from a Cocoa Processing Industry

Abstract This study investigated the constituents and haematotoxic potential of wastewater collected from a cocoa processing industry in mice. The mice were intraperitoneally injected for 5 consecutive days with 0.3mL of 1, 5, 10, 25 and 50% concentrations of the wastewater. Blood was collected from some mice on the last day of the injection to assess the immediate effect of the wastewater on selected haematological parameters while blood was collected from others 21 days after the last injection to assess its residual effect. Blood collected were analyzed using an Abacus Reflotron machine. Haematological parameters including packed cell volume (PCV), white blood cells (WBC), red blood cells (RBC), heamaglobin (HGB), lymphocytes, erythrocyte indices: Mean corpuscular heamaglobin count (MCHC), mean corpuscular heamablobin (MCH), mean corpuscular volume (MCV); leucocyte differential count: Neutrophils, Monocytes, Basophils and Eosinophils were analyzed. A significant decrease in basophils, MCH, MCHC, HGB, and PCV; and a significant increase in neutrophils, monocytes, eosinophils, MCV, total WBC count, and lymphocytes were observed in mice exposed to the wastewater compared to the negative control after 5 days. A similar trend of the alterations of the heamatological parameters was observed in mice 21 days after exposure, even though the values were numerically lower than in the 5 days exposed mice. Results further showed the presence of Zn, Cd, As, Mg, Ni, Cu, Fe, Cr, BOD, COD, and EC at concentrations higher than allowable limit by standard organization. Cocoa industry wastewater is capable of inducing hematotoxicity, therefore, proper waste management should be followed in the disposal of such toxic waste.