Baseline assessment of the health risk of potentially toxic heavy metals in commonly consumed vegetables in parts of Mamfe, Southwest Region, Cameroon

Introduction

Heavy metals contained in vegetables play a significant role in chemical, biological, biochemical, metabolic, catabolic, and enzymatic reactions in the living cells of plants, animals, and humans. Vegetables take up heavy metals (Cd, Cu, Mo, Pb, and Zn) and accumulate them in their edible and non-edible parts in high quantities to cause clinical problems for animals and humans.

Objective

This study evaluated the concentration level of heavy metals, estimated the average daily intake (ADI), and evaluated the health risk (HRI) of the heavy metals in the commonly consumed vegetables in parts of Mamfe, the southwest region of Cameroon. Using an atomic absorption spectrophotometer, One hundred and eleven vegetable samples were harvested, prepared, and analyzed for Cd, Cu, Mo, Pb, and Zn.

Results

The results revealed that the order of heavy metal concentration is based on the overall mean: Zn > Cu > Pb > Mo > Cd. The mean concentrations of Pb exceeded the permissible limit of the Food and Agricultural Organisation/World Health Organisation. The pollution index (PI) values of Pb for all the samples and Cd for the cocoyam leaf were greater than 6, suggesting a very high pollution level for these metals, which are considered unsuitable for consumption. The mean values of PI decreased in the order of Pb > Cd > Zn > Mo > Cu. The ADI of the PTHM for all age categories was below the provincial tolerable daily intake (PTDI) and oral reference dose (RFD). Pb contributed the highest to the dietary intake of the PTHMs. The hazard Index (HI) level was more than 1 for noncarcinogenic risk for Cd and Pb via consumption of cocoyam, green, eggplant, and pumpkin leaves for adults, teens, and children.

Conclusion

This study constitutes the first detailed study on dietary exposure risks through the consumption of various vegetables grown in the southwest region of Cameroon. HI > 1 indicates potential high health risks through consuming these vegetables. It is recommended that other food pathways and sources of PTHMs exposure, like dust inhalation and dermal contact, need to be evaluated.