Determination of Heavy Metals (Lead, Zinc, Nickel and Cadmium) in Medicinal Plants (Scent Leaf and Pawpaw) in Bayelsa State, Nigeria

Aims: This study investigated the level of zinc, nickel, lead and cadmium in selected medicinal plants - Scent Leaf (Ocimum gratissimum) and Pawpaw (Carica papaya) that are traditionally used in alternative medicine in Amassoma community, Bayelsa State, Nigeria.

Study Design: Scent leaf (Ocimum gratissimum) and Pawpaw (Carica papaya) from where these plants are grown were randomly collected for heavy metal analysis from within Amassoma community in Southern Ijaw Local Government Area of Bayelsa State, Nigeria

Place and Duration of Study: This study was carried out in Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Amassoma, Bayelsa State between March 2019 to September 2019

Methodology: Scent leaf (Ocimum gratissimum) and Pawpaw (Carica papaya) were digested and analyzed for heavy metals using Atomic Absorption Spectrophotometer (AAS, model S471096). The method used was wet-ashing method for the analysis.

Results: The result showed that the concentration of Lead in the pawpaw fruit with 5.99mg/kg and pawpaw seed with 3.72mg/kg, were above the WHO permissible limit. While the concentration of Cadmium in the pawpaw fruit, pawpaw leaf, pawpaw seed and scent leaf with 1.32mg/kg, 0.96mg/kg, 0.21mg/kg, and 0.59mg/kg, were all above the permissible limits. Again, Zinc in the pawpaw fruit, pawpaw leaf, pawpaw seed and scent leaf were 2.52mg/kg, 2.53mg/kg, 5.30mg/kg, and 0.79mg/kg respectively, and these are also above the permissible limit. While that of the concentration of Nickel in the pawpaw fruit, pawpaw leaf, pawpaw seed and scent leaf were observed to be within permissible limit.

Conclusion: It is therefore recommended that caution should be taken when such plants are to be used as alternative to conventional medicine as excess of it could pose the risk of bioaccumulation and possible health effects in humans.