Toxic and some essential metals in medicinal plants used in herbal medicines: A case study in Pakistan

Overview

Khan and colleagues measured lead, nickel, cadmium, and chromium in eight medicinal plant species collected near Kallar Kahar Lake in Punjab, Pakistan. The paper is occurrence evidence for herbal-botanical raw materials used in traditional medicine, with paired soil concentrations as collection-site context. Values are reported as total elemental metals in mg/kg; chromium is total chromium (Cr), not hexavalent chromium (Cr-VI).

Key numbers

All values below are from Table 5 and are reported as mean concentrations in mg/kg in medicinal plants. The source describes plant sampling as three replicates of each plant at each location. No unit conversion or wet/dry conversion is applied.

The plant table maxima are lead (Pb) 6.696 mg/kg in Dodonaea viscosa at Site II, nickel (Ni) 3.641 mg/kg in Dodonaea viscosa at Site I, cadmium (Cd) 0.086 mg/kg in Paganum hermala at Site II, and total Cr 4.651 mg/kg in Cannabis sativa at Site I.

Paired soil values are collection-site context and should not be pooled as medicinal-plant occurrence.

The abstract and results text summarize plant concentration ranges as Site I Pb 5.78 to 6.27, Ni 3.25 to 3.64, Cd 0.025 to 0.040, and Cr 3.40 to 4.65 mg/kg; and Site II Pb 6.28 to 6.69, Ni 3.20 to 3.62, Cd 0.066 to 0.086, and Cr 3.87 to 4.27 mg/kg.

Methods (brief)

The study area was a sub-urban area of Kallar Kahar, Chakwal District, Punjab, Pakistan. The authors collected Dodonaea viscosa, Withania somnifera, Solanum nigrum, Calotropis gigantea, Mentha spicata, Paganum hermala, Cannabis sativa, and Adhatoda vasica from two locations around Kallar Kahar Lake in September 2012, with three plant replicates per species per location. Plant samples were stored in plastic food-grade containers, dried at 70 °C for 48 hours, washed with distilled water and diluted HCl, digested with HNO3/HClO4 in a 9:1 ratio, diluted to 25 ml, and analyzed for Pb, Ni, Cd, and Cr using a Shimadzu AAS 6300 atomic absorption spectrophotometer. The source reports total metals; no arsenic, mercury, or chromium speciation is reported.

Implications

The paper contributes Pakistan occurrence data for medicinal-plant raw materials, with a compact two-site table for Pb, Ni, Cd, and total Cr. The paired soil rows can support collection-context and soil-to-plant notes, but the product occurrence evidence is the Table 5 medicinal-plant concentration table.

Related evidence

• Ingredient class — botanicals/herbs/traditional formulas
• Herbal botanicals
• Dried Herbs
• Lead
• Nickel
• Cadmium
• Chromium

Update history

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