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Assessment of heavy metal contamination in herbal medicinal products consumed in the Iranian market

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Herbal medicines have been reported to contain many contaminants that are potential harmful to health. These include heavy metals, such as lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg). Therefore, this study aimed to measure the levels of Pb, Cd, As, and Hg in several orally administered herbal products available in the Iranian market. Fifteen products labeled (A-O) of different brands from three different production batches (n = 45) were purchased from traditional herbal medicine factories in Iran. Each sample was digested with nitric acid by the wet digestion method, and the resultant solutions were used to determine the concentrations of Pb, Cd, As, and Hg. These measurements were performed using flame atomic absorption spectrometry, graphite furnace atomic absorption, or cold vapor atomic absorption. The lead, cadmium, arsenic, and mercury contents in the investigated samples did not show significant levels that may be associated with toxicity. All four metals were present at concentrations below the limits recommended by the WHO (World Health Organization), American Herbal Products Association (AHPA), and Canadian standard, but in several herbal products, the concentrations of these trace elements exceeded the Agency for Toxic Substances and Disease Registry (ATSDR). The concentrations of Pb, Cd, As, and Hg in commercially available herbal remedies were well below the acceptable intake recommended by global recommendations. Our findings revealed that at present, the amount of heavy metals in medicinal herbs processed at the level of supply by pharmacies licensed is favorable.

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All data generated or analyzed during this study are included in this published article.











World Health Organization


American Herbal Products Association


Agency for Toxic Substances and Disease Registry


Food and Agriculture Organization/World Health Organization


Minimum risk level




US Environmental Protection Agency


Hazard quotient


Hazard index


Daily intake reference dose


Brain-derived neurotrophic factor


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We would like to express our gratitude to Dr. Abbas Jafarian- Dehkordi at Department of Pharmacology and Toxicology, Isfahan University of Medical Sciences, for technical assistance.


This study was supported by Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran.

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Authors and Affiliations



MK, RN, MN and SNN wrote the manuscript. MK prepared and analyzed all biological samples. SA designed research. MK and RN interpreted all obtained data and were major contributors in writing the manuscript. GAF revised the manuscript critically for important intellectual content. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Sedigheh Asgary.

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This article does not contain any studies with human participants or animals performed by any of the authors.

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Informed consent was obtained from all individual participants in the study.

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The authors declare no competing interests.

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Responsible Editor: Elena Maestri

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Keshvari, M., Nedaeinia, R., Nedaeinia, M. et al. Assessment of heavy metal contamination in herbal medicinal products consumed in the Iranian market. Environ Sci Pollut Res 28, 33208–33218 (2021).

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