Evaluation of heavy metal contamination and toxicological risk of selected Moringa oleifera products in Southwest Nigeria

Background: Heavy metals are the main sources of pollution in the environment and its determination is important in enhancing production efficiency in plants.

Objectives: This study determined the concentrations of selected heavy metals, trace and essential elements present in thirteen (13) Moringa oleifera products marketed in southwest Nigeria.

Methods: Each Moringa sample was digested with a mixture of concentrated nitric acid and sulphuric acid (3:1 v/v) and subjected to standard heavy metal analysis using the atomic absorption spectrometric technique. Calibration curves of absorbance against concentration were plotted to determine unknown metal concentration.

Results: The elements analysed were present in varying concentrations. Cadmium concentrations was between 0.0011 to 0.0030 mg/kg, lead ranged between 0.0010 to 0.0110 mg/kg, while calcium ranged between 145.7 to 957.2mg/kg. Copper ranged between 0.35 to 38.9 mg/kg and that of sodium fell between 105.9 to 947.6 mg/kg. Comparison of these concentration values with the World Health Organisation, WHO/Nigerian National Agency For Food And Drug Administration And Control, NAFDAC standards revealed varying levels of compliance with permissible levels set by these agencies.

Conclusion: Based on present safety and permissible standards, the Moringa products selected in the present study were found to be safe for human consumption.