Did you already check the FAO/WHO website for this information?

Here are the permissible limits for heavy metals in herbal medicinal plants according to various standards:

FAO/WHO Guidelines

- **Cadmium (Cd)**: 0.3 mg/kg

- **Lead (Pb)**: 10 mg/kg

- **Copper (Cu)**: 20 mg/kg

- **Chromium (Cr)**: 0.5 mg/kg

- **Nickel (Ni)**: 5 mg/kg

Canada (Health Canada)

- **Cadmium (Cd)**: 0.3 mg/kg

- **Lead (Pb)**: 10 mg/kg

- **Copper (Cu)**: 20 mg/kg

- **Chromium (Cr)**: 1 mg/kg

- **Nickel (Ni)**: 5 mg/kg

China (GB Standards)

- **Cadmium (Cd)**: 0.3 mg/kg

- **Lead (Pb)**: 10 mg/kg

- **Copper (Cu)**: 20 mg/kg

- **Chromium (Cr)**: 2 mg/kg

- **Nickel (Ni)**: 5 mg/kg