Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This review examined the presence, sources, and clinical consequences of heavy metal contamination in Traditional Chinese Medicines (TCMs). The review synthesized data from 22 publications covering case reports, epidemiological studies, and analytical investigations up to December 2000. The authors systematically retrieved literature from major biomedical databases such as MEDLINE, Embase, and the Cochrane Library, targeting reports documenting original data on heavy metal content in TCMs. Articles that did not specify the origin of the remedies or that analyzed only crude manufacturing ingredients were excluded. The review aimed to provide a comprehensive assessment of the risks posed by heavy metals, including arsenic, lead, mercury, cadmium, and thallium found in TCMs, as well as to evaluate the potential health impacts and regulatory implications for global health and safety.
Who was reviewed?
The populations and cases reviewed included individuals across Asia, the United States, and Europe who had consumed TCMs and subsequently experienced heavy metal poisoning. The systematic review encompassed 106 documented cases of poisoning, with patients ranging from infants to older adults, as well as broader epidemiological samples such as 2,803 Taiwanese adults and 319 children. Analytical studies included testing of TCM samples from Chinese, Taiwanese, Singaporean, German, and US sources. Additionally, the review referenced regulatory and hospital quality control data, broadening the scope to include both users and products distributed internationally. The review also considered the intentional use of heavy metals in TCMs, with a detailed list of traditional remedies that contain known toxic ingredients.
Most important findings
| Aspect | Details |
|---|---|
| Clinical Cases | 106 cases of heavy metal poisoning linked to TCMs (primarily arsenic, lead, and mercury), with symptoms ranging from skin and neurological issues to acute renal failure and death. Children were especially vulnerable. Case documentation included confirmed elevated blood or urine heavy metal levels and, in some cases, direct analysis of the consumed TCM. Malignancies, permanent sequelae, and fatalities were reported. |
| Epidemiological Evidence | Population-based studies in Taiwan revealed TCM use as a significant risk factor for elevated blood lead levels (odds ratio 3.09 in adults). Children consuming specific TCMs (e.g., ba-baw-san) had statistically significant higher blood lead concentrations, with differences notable at the 1% significance level. |
| Analytical Investigations | Laboratory analyses found toxic levels of heavy metals in TCM samples: mercury in 6 of 11 samples, arsenic in 4, and lead in 6. “Herbal balls” confiscated at US customs contained up to 621.3 mg mercury and 36.6 mg arsenic per unit, with recommended dosages posing serious acute toxicity risk. A large Singaporean study found 42 of 2,080 proprietary medicines exceeded legal heavy metal limits. In Germany, 3.5% of TCM shipments to a hospital contained heavy metals above legal limits. |
| Intentional vs. Accidental Inclusion | Many TCMs intentionally include heavy metals for supposed therapeutic effect, using ingredients like cinnabaris (mercuric sulfide) and realgar (arsenic sulfide). Table III listed dozens of TCMs containing such substances. Contamination may also result from manufacturing practices or environmental pollution affecting source materials. |
| Regulatory Implications | The review noted regulatory gaps, especially in countries where TCMs are categorized as dietary supplements, and highlighted the difficulty of monitoring internet sales. Most reports originated from Asia and the West, showing that the issue is global. The authors suggested that current cases likely represent only the visible portion of a much larger problem due to underreporting and detection limitations. |
Key implications
The systematic review highlights the urgent need for rigorous heavy metal testing and certification of traditional Chinese medicines worldwide, as unregulated TCMs present a clear and ongoing risk of heavy metal poisoning, including fatal cases, especially among children. Regulatory authorities and heavy metal certification programs like HTMC must address intentional inclusion and accidental contamination, enforce standardized testing, and raise awareness among healthcare professionals and consumers to mitigate these health hazards.
Citation
Ernst E, Thompson Coon J. Heavy metals in traditional Chinese medicines: A systematic review. Clin Pharmacol Ther. 2001;70(6):497-504. doi:10.1067/mcp.2001.120249
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
