Levels of Heavy Metals in Commonly Consumed Vegetables Obtained from Some Markets in Ota, Nigeria

Abstract

Background: As a result of increasing environmental pollution in developing countries, Nigeria in particular, assessment of food contamination is necessary. Objectives: This study aimed at assessing the concentrations of heavy metals in vegetables available in selected markets at Ota, Ogun State. Method: A total of 75 samples of three edible leafy vegetables: fluted pumpkin leaves (Telfairia occidentalis), Lagos spinach, "Green" (Amaranthus hybridus) and Jute Mallow (Corchorus olitorius) were obtained from Iyana Iyesi, Ota, Oju-Ore, Sango-Ota and Toll-gate markets in Ado-Odo/Ota local government, Ogun State, Nigeria. The samples were digested and analyzed for heavy metals using Atomic Absorption Spectrophotometer (AAS) following a standard method. Results: The results showed that all the metals detected were above the WHO/FAO permissible limits. Lead (Pb) was detected in all the vegetables except Jute Mallow from Sango and Fluted Pumpkin in Toll gate. The Pb content in all the vegetables ranged from 0.269±0.36 to 12.601±1.80 mg/kg. Cadmium was also detected in all the vegetables except Lagos Spinach (obtained from Sango Ota) and Fluted Pumpkin (obtained from Iyana Iyesi). The Cd content in all the vegetables ranged from 0.156±0.04 to 0.832±0.03 mg/kg. Chromium (Cr) was not detected in all the vegetables sold at Sango and also in Fluted pumpkin from Iyana Iyesi Market. The Cr content in all the vegetables ranged from 0.508±1.09 to 1.799±1.19 mg/kg. Conclusion: With regards to the locations or markets, the differences in concentrations were significant (P<0.05), while with regards to the metals, the differences in the concentrations were not significant. With significant values of Lead, Cadmium and Chromium observed in samples, vegetable consumers must be wary of vegetables to buy and the source.

Keywords: Heavy metals, vegetables, Telfairia occidentalis, Amaranthus hybridus, Corchorus olitorius, Ado-Odo/Ota