DETERMINATION OF MANGANESE AND CADMIUM IN SOIL, WATER AND AMPHIBIANS FROM POLLUTED STATIONS IN BENIN CITY AND HEALTH RISK ASSESSMENT IN EDIBLE FROGS

ABSTRACT

The relationship between heavy metals and amphibians is very complex. Heavy metals exist naturally as essential nutrients in small quantities but can become toxic at increased concentrations leading to adverse effects in amphibians, this has made them valuable tools to access heavy metal damage to the environment. This study was carried out in four different sample stations which are Iguosa river, Oluku dumpsite, Life Sciences premises of UNIBEN and Ikpoba river to investigate the presence of heavy metals particularly Cadmium and Manganese in the soil, water and amphibian toe snip samples collected from the stations. A spectrochemical analysis of the samples was performed using the Analyst 200 Perkin Elmer series of Atomic Absorption Spectrophotometry. The results show that of all the sample stations, Iguosa river had the highest concentration of Cadmium and manganese in its amphibians ranging from 0.054 to 0.074 for manganese and 0.009 to 0.015 for cadmium, while Oluku had the highest amount of Manganese (12.847) and cadmium(2.887) in its soil and Ikpoba river had the highest amount of Manganese in its water (0.72) but Cadmium levels in water was Below Discovery Concentrations (BDC) in all sample sites. Cadmium and Manganese concentrations in all amphibian toe snip samples were within the permissible limits by WHO and FAO but Manganese concentrations at Iguosa river exceeded the permissible limits by FEPA and USFDA. Comparison of the Estimated Weekly Intake (EWI) to the Tolerable Weekly (PTWI) shows that the amphibians from all sample stations pose a low health risk to consumers.