Abstract

The spate of natural emissions and anthropogenic activities has comparatively increased cadmium pollution in recent times. This has also increased the attendant hazardous implication on both the aquatic and terrestrial ecosystems. In this study, a total of 50 edible frog species (Hoplobatrachus occipitalis) sourced from the Ogunpa river in Ibadan, Oyo state were sampled. Atomic Absorption Spectrophotometry (AAS) was used for the evaluation of the blood, kidney and liver cadmium level. The frogs were grouped into Below Permissible Limit (BPL) and Above Permissible Limit (APL) groups using the FAO/WHO cadmium permissible level of 0.5mg/kg. 86% of the sampled frogs had blood cadmium level above the permissible limit while the liver and kidney cadmium levels exceeded the permissible limits in all the frogs. The highest cadmium level was detected in the liver (3.02±1.23 mg/kg). The erythrocyte parameters were significantly lower in the APL compared to the BPL group while the leucocyte parameters were higher in the APL than the BPL group. The histopathological lesions were consistent with pathological changes associated with renotoxic, hepatotoxic and reproductive features of cadmium toxicity. The study highlights the elevated cadmium levels in the tissue of the frog as a biomarker of exposure while the haematological and histopathological changes served as biomarkers of effect associated with cadmium toxicity in naturally exposed frogs. It also serves to underscore the importance of frogs as important sentinels of environmental cadmium toxicity, creation of public health awareness for cadmium toxicity and the evaluation of cadmium toxicity in the ecosystem.

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