Pb and Cd in medicinal plants (Case study: Shirazi thyme, sweet violet, pennyroyal and jujube)

Medicinal plants are a major source of drugs for the majority of people in the world. Unfortunately, little data is available on the safety of medicinal plants, especially in terms of heavy metal contamination. Therefore, this study was conducted to evaluate the potential risk of Pb and Cd in Shirazi thyme, sweet violet, pennyroyal and jujube marketed in Hamedan City in 2015.
After preparation of 3 samples of each medicinal plant and acid digestion of the samples according to standard methods, the concentration of elements in samples were determined using atomic absorption spectrophotometer (AAS) in 3 replicates. Also, all statistical analyses were performed in the SPSS software.
The results showed that the maximum mean concentrations of Pb and Cd in specimens were 1420±30 and 40±30 µg/kg for thyme and viola, respectively. The results of health index for all samples were smaller than one for all samples. Also the mean concentrations of Pb and Cd in all samples were lower than WHO permissible limits.
Controlled consumption of medicinal plants has no adverse effects on the consumers’ health. However, given the increased use of pesticides, chemical fertilizers, sewage sludge and wastewater by farmers, it is recommended that medicinal plants be regularly monitored for chemical pollutants especially heavy metals.