ABSTRACT
It has long been established that crude petroleum oil (CPO) is deleterious to the ecosystem (soil, animals, and plants). The link between these forms of pollution to man has been an area of interest. Contamination from cadmium (Cd) and CPO components are mainly from the drinking water or food of a population. The study was aimed at contributing to the studies of the effects of co-administration of crude petroleum oil and cadmium through fish contamination and its link through the food-chain to humans.
Sixty-four (64) male albino rats of Wistar strain were divided into four groups (A, B, C and D) of 16 rats each. Test groups (B, C and D) were fed formulated diet made from Cd (4 ppm), CPO (0.8 ppm) and Cd + CPO-exposed fish, respectively. Control group (A) was fed diet not exposed to Cd and CPO. All animals were fed 320 g of feed daily and allowed access to drinking water ad libitum. After 4 weeks, half the number of rats in each group were sacrificed, while the other half were sacrificed after 8 weeks under mild chloroform anaesthesia. Whole blood was collected for haematological studies. The intestine and stomach were used to assay for the activities of digestive and absorption enzymes. Portion of the small intestine was kept for histopathological examination, while the faecal matter in the colon was cultured.
Cd and total hydrocarbon (THC) contents were significantly increased (p < 0.05) in the test feeds made from Cd and CPO-exposed fish (singly and combined) respectively, when compared to control. The findings of the study revealed a significantly decreased (p < 0.05) body weight gain in the rats from test groups at both 4 and 8 weeks when compared to control. No significant difference (p ˃ 0.05) was seen in the organ/body weight ratios in the test groups at both 4 and 8 weeks when compared to the control. There was no significant difference (p ˃ 0.05) in white blood cell (WBC) count, red blood cell (RBC) count, haematocrit (HCT) and mean corpuscular haemoglobin concentration (MCHC) in test groups at 4 weeks when compared to control. However, there was a significant decrease (p < 0.05) in WBC count, RBC count, HGB, HCT, MCHC and Mean corpuscular volume (MCV) in test groups at 8 weeks compared to control. There was a significant reduction (p < 0.05) in the activities of protein, carbohydrate and lipid digestive and absorption enzymes in the rats at 8 weeks, while at 4 weeks there was no significant difference (p ˃ 0.05) observed. Histopathology of the duodenum showed altered architecture resulting from Cd and CPO exposures. Microbial culture of faeces from the colon revealed presence of probiotic bacteria. The results suggest a compromise of the digestive system occasioned by the decreased ATPase activities which have consequences on the absorption and transport of nutrients and cells viability which contributed to the observed decrease in weight gain. Thus, Cd and CPO co-administration greatly alter digestion and absorption activities as a direct effect of toxicity.
