For heavy metal contamination in CHMs, our resultoffered the novelty of documenting heavy metal concentrations in boiled decoctions, as existing literatures mainly discussed metal levels in non-boiled CHMs.
We found that Pb concentrations in boiled and non-boiled samples were 1.028 and 0.750 mg/L, well within the permissible level of 10 mg/L.28
However, we detected higher concentrations of Cd from boiled decoctions in samples CHM3A and CHM4A, exceeding slightly the 0.3 mg/L permissible level.28
The higher concentrations of Cd in herbal medicine appeared to be a common finding. High Cd levels were also detected in 79 samples of various herbal medicines in Italy
(up to 0.75 mg/L) and in ginseng purchased from the US, Europe and Asia.
We postulate that this could be associated with the fact that most plants naturally
had active Cd uptake via roots which then remained in the plant tissues.
We do not have permissible levels of Cu, Zn, Mn and Fe as they are not yet identified as major health hazards in CHMs. Nevertheless, these trace elements are now increasingly found in the environment as a result of heavy usage of pesticides
(Cu-based pesticides) leading to groundwater contamination,and the overuse of Mn-based fungicides.
These heavy metals must be monitored especially since Mn and Fe have potential to increase in concentrations in boiled decoctions as determined in this study.
These metals must be monitored to reduce the risk of bioaccumulation of metals in our body upon consumption.