Industrialization has led to huge waste generation over the last decades, the absence of
adequate facilities for treating such wastes in most developing nations has led to the
discharge of effluents into the environment without proper treatment. Toxicological effects
of effluents from rubber processing plant (collected during the period of low rivertide i.e.
between October 2012 and February 2013) were carried out in this study. Lethal
concentration (96-h LC50) was evaluated using 0.25mg/L, 0.30mg/L, 0.35mg/L and
0.40mg/L while sub-lethal effects (42 days) was carried out on haematological parameters
like Red Blood Cell (RBC), White Blood Cell (WBC), Haemoglobin (Hb), Packed Cell
Volume (PCV), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH)
and Mean Corpuscular Haemoglobin Concentration (MCHC) using 0.064mg/L, 0.048mg/L,
0.032mg/L and 0.016mg/L which are the 20%, 15%, 10% and 5% of the 96-h LC50 value.
Mortality increased as the concentrations of the effluent increases and 0.32mg/L was
obtained as LC50. In comparison with the control, the mean value obtained for PCV, HB
and RBC showed significant differences (P<0.05) most especially at highest concentration
while there was no significant difference in all values obtained for WBC, MCV, MCH and
MCHC. It was concluded that the rubber processing effluent had some negative effect on
the haematology of Clarias gariepinus. Therefore, it is recommended that the effluent
should be properly treated before discharge into the environme
