Impact of metal bioaccumulation on cytogenotoxic, haemato-biochemical and histopathological parameters of toads and lizards collected from a North-central University community, Nigeria

The potential of toads ( Amietophrynus regularis) and lizards ( Agama agama) as biomarkers for assessing environmental pollution levels was investigated at Anyigba, Nigeria. Soil, toad, and lizard specimens were sampled from five different locations within the study area. The soil samples, as well as tissues from the skin, alimentary canal, testes, liver, and kidney were analyzed for heavy metals using Atomic Absorption Spectrophotometer. Blood was sampled for cytogenetic, heamatological and biochemical analysis while histopathological assays were conducted to assess possible injuries in animal tissues. The metal concentration levels in the sampled soil followed the sequence Mn> Fe > Zn >Pb> As > Cd > Cr. The various tissues of the animals exhibited high bioaccumulation of Fe, Mn, and Zn, while Cd, As, and Cr were detected in lower amounts. Histopathological examinations showed mild abnormal tissue lesions, necrosis, congestion, infiltration, and inflammation in the observed organs. There was decrease in red blood cell (RBC) counts but significant increase in white blood cells (WBCs) and lymphocytes in both animals. There were no significant alterations in the biochemical parameters compared to the control. The study demonstrated significant induction of micronuclei (MN) and nuclear abnormalities such as bi-nucleated blood erythrocytes, nuclear bud, notch nucleus, vacuolated nucleus, and lobed nucleus in the toads and lizards, suggesting cytotoxic effects from the environment. The results obtained suggest pollution of the community and demands crucial environmental monitoring and control to reduce the possible health risks on the faunal community in the environment. • Analysis of Soil revealed metals pollution index significantly higher than standard limits. • Soil metal concentrations follows Mn > Fe > Zn > Pb > As > Cd > Cr. • Toad and Lizard exhibited high bio-accumulation of Fe, Mn, Zn while Cd, As, and Cr were low. • Abnormal tissue lesions, necrosis, congestion, infiltrations and inflammations were observed in animal organs. • Micronuclei and nuclear abnormalities were observed in the toads and lizards.