Abstract
Heavy metal contamination in herbal medicines is a global threat to human beings especially at levels above known threshold concentrations. The concentrations of five heavy metals cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg) and copper (Cu) were investigated using Inductively Coupled Plasma Optical Mass Spectrometry (ICP-MS) with 1773 samples around the world. According to Chinese Pharmacopoeia, 30.51% (541) samples were detected with at least one over-limit metal. The over-limit ratio for Pb was 5.75% (102), Cd at 4.96% (88), As at 4.17% (74), Hg at 3.78% (67), and of Cu, 1.75% (31). For exposure assessment, Pb, Cd, As, and Hg have resulted in higher than acceptable risks in 25 kinds of herbs. The maximal Estimated Daily Intake of Pb in seven herbs, of Cd in five, of Hg in four, and As in three exceeded their corresponding Provisional Tolerable Daily Intakes. In total 25 kinds of herbs present an unacceptable risk as assessed with the Hazard Quotient or Hazard Index. Additionally, the carcinogenic risks were all under acceptable limits. Notably, As posed the highest risk in all indicators including Estimated Daily Intake, Hazard Index, and carcinogenic risks. Therefore further study on enrichment effect of different states of As and special attention to monitoring shall be placed on As related contamination.
Highlights
Having been utilized as traditional folk remedies for thousands of years (Maiga et al, 2005), medicinal plants gained an increasingly important role in the pharmaceutical, health food, and natural cosmetic industries (Kim et al, 2016)
It was reported that a total of 60,107 COVID-19 cases (85.20% of the total cases) in China were treated by Chinese herbal medicines with positive results in all infection stages, including significant symptom management, lower rates of deterioration and mortality, faster recovery as well as disease prevention on February 17, 2020
The orders of mean concentrations detected of five heavy metals in five plant properties are: for Cu, flos > herba and others > folium and cortex > radix and rhizoma > fructus and semen; for As, herba and others > folium and cortex > flos > radix and rhizoma > fructus and semen; for Cd, flos > herba and others > radix and rhizoma > folium and cortex > fructus and semen; for Hg, flos > fructus and semen > herba and others > folium and cortex > radix and rhizoma; while for Pb, herba and others > folium and cortex > flos > radix and rhizoma > fructus and semen (Figure 1)
Summary
Having been utilized as traditional folk remedies for thousands of years (Maiga et al, 2005), medicinal plants gained an increasingly important role in the pharmaceutical, health food, and natural cosmetic industries (Kim et al, 2016). Concerns grew regarding the safety of herbal medicines after studies indicated that high levels of heavy metals were present in some herbal medicines This was a problem more frequently encountered in traditional medical therapy, considered to be a cause of several health disorders (Maiga et al, 2005; Brookes et al, 2019). As heavy metals are known to have low renal excretion rates, potentially resulting adverse effects in humans even at very low concentrations (Jamroz et al, 2015) They are not metabolized by body and are found to accumulate in the soft tissues (Jiwan and Kalamdhad, 2011). It is necessary and a matter of urgency to conduct a comprehensive risk assessment of heavy metal contamination in herbal medicines
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