Toxic metal contamination in Artemisia annua L. herbal preparations from different commercial sources in China

Contamination of herbal medicinal products in low-and-middle-income countries: A systematic review

The use of herbal medicinal products (HMPs) has grown significantly across low-and-middle-income countries (LMICs). Consequently, the safety of these products due to contamination is a significant public health concern. This systematic review aimed to determine the prevalence, types, and levels of contaminants in HMPs from LMICs. A search was performed in seven online databases, i.e., Africa journal online (AJOL), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Directory of Open Access Journals (DOAJ), Health Inter-Network Access to Research Initiative (HINARI), World Health Organization Global Index Medicus (WHO GIM), Scopus, and PubMed using appropriate search queries and reported as per the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guidelines. Ninety-one peer-reviewed articles published from 1982 to 2021 from 28 different countries across four continents were included in the study. Although metals, microbial, mycotoxins, pesticides, and residual solvents were the reported contaminants in the 91 articles, metals (56.0%, 51/91), microbial (27.5%, 25/91), and mycotoxins (18.7%, 17/91) were the most predominant. About 16.4% (1236/7518) of the samples had their contaminant levels above the regulatory limits. Samples tested for microbial contaminants had the highest proportion (46.4%, 482/1039) of contaminants exceeding the regulatory limit, followed by mycotoxins (25.8%, 109/423) and metals (14.3%, 591/4128). The proportion of samples that had their average non-essential metal contaminant levels above the regulatory limit was (57.6%, 377/655), 18.3% (88/480), 10.7% (24/225), and 11.3% (29/257) for Pb, Cd, Hg, and As, respectively. The commonest bacteria species found were Escherichia coli (52.3%, 10/19) and Salmonella species (42.1%, 8/19). This review reported that almost 90% of Candida albicans and more than 80% of moulds exceeded the required regulatory limits. HMP consumption poses profound health implications to consumers and patients. Therefore, designing and/or implementing policies that effectively regulate HMPs to minimize the health hazards related to their consumption while improving the quality of life of persons living in LMICs are urgently needed.

Applied Analytical Methods for Detecting Heavy Metals in Medicinal Plants

For thousands of years, medicinal plants (MPs) have been one of the main sources of drugs worldwide. However, recently, heavy metal pollution has seriously affected the quality and safety of MPs. Consuming MPs polluted by heavy metals such as Pb, Hg, and Cu significantly threaten the health of consumers. To manage this situation, the levels of heavy metals in MPs must be controlled. In recent years, this field has attracted significant attention, but few researchers have systematically summarized various analytical methods. Therefore, it is necessary to investigate methods that can accurately and effectively detect the amount of heavy metals in MPs. Herein, some important analytical methods used to detect heavy metals in MPs and their applications have been introduced and summarized in detail. These include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry, X-ray fluorescence spectrometry, neutron activation analysis, and anodic stripping voltammetry. The characteristics of these methods were subsequently compared and analyzed. In addition, high-performance liquid chromatography, ultraviolet spectrophotometry, and disposable electrochemical sensors have also been used for heavy metal detection in MPs. To elucidate the systematic and comprehensive information, these methods have also been briefly introduced in this review.

Speciation and bioaccessibility of arsenic in traditional Chinese medicines and assessment of its potential health risk

Arsenic in traditional Chinese medicines (TCMs) has caused public concerns about its health risk in recent years due to the high toxicity of arsenic and widespread use of those medicines throughout the world. However, in previous studies the arsenic toxicity was usually overestimated by considering the total arsenic concentration only. This work investigated the total concentration, speciation and bioaccessibility of arsenic in 84 commonly used traditional Chinese patent medicines (CPMs) and Chinese herbal medicines (CHMs) to evaluate arsenic's potential health risks to human. Arsenic was found in all the CPMs and 88% of CHMs at concentrations ranging from 0.033 to 91,000mgkg^-1 and 0.012 to 6.6mgkg^-1, respectively. The bioaccessibility of arsenic varied significantly and was in the range of 0.21%-90% in the CPMs and 15%-96% in the CHMs, with inorganic arsenic as the predominant species. The average daily intake dose (ADD) and hazard quotient (HQ) of arsenic in most of medicines were within the safe limits, while in certain medicines, they exceeded the safe threshold level. These excesses remind us that the potential health risk by consumption of several medicines may not be negligible and more control and monitoring of arsenic in medicines should be carried out.

Sources, distribution, bioavailability, toxicity, and risk assessment of heavy metal(loid)s in complementary medicines

The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines.

Quality assessment of trace Cd and Pb contaminants in Thai herbal medicines using ultrasound-assisted digestion prior to flame atomic absorption spectrometry

A simple, efficient, and reliable ultrasound-assisted digestion (UAD) procedure was used for sample preparation prior to quantitative determination of trace Cd and Pb contaminants in herbal medicines using flame atomic absorption spectrometry. The parameters influencing UAD such as the solvent system, sample mass, presonication time, sonication time, and digestion temperature were evaluated. The efficiency of the proposed UAD procedure was evaluated by comparing with conventional acid digestion (CAD) procedure. Under the optimum conditions, linear calibration graphs in a range of 2–250 μg/L for Cd, and 50–1000 μg/L for Pb were obtained with detection limits of 0.56 μg/L and 10.7 μg/L for Cd and Pb, respectively. The limit of quantification for Cd and Pb were 1.87 μg/L and 40.3 μg/L, respectively. The repeatability for analysis of 10 μg/L for Cd and 100 μg/L for Pb was 2.3% and 2.6%, respectively. The accuracy of the proposed method was evaluated by rice flour certified reference materials. The proposed method was successfully applied for analysis of trace Cd and Pb in samples of various types of medicinal plant and traditional medicine consumed in Thailand. Most herbal medicine samples were not contaminated with Cd or Pb. The contaminant levels for both metals were still lower than the maximum permissible levels of elements in medicinal plant materials and finished herbal products sets by the Ministry of Public Health of Thailand. The exception was the high level of Cd contamination found in two samples of processed medicinal plants.

Evaluation of portable XRF instrumentation for assessing potential environmental exposure to toxic elements

Portable instruments based on X-Ray Fluorescence Spectrometry (XRF) have the potential to assist in field-based studies provided the data produced are reliable. In this study, we evaluate the performance of two different types of XRF instrument (XOS prototype, and Thermo Niton XL3t). These two XRF analyzers were evaluated in a laboratory setting, and data were reported for 17 elements (As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, Sr, Ti, V, and Zn). Samples analyzed (n=38) included ethnic herbal medicine products (HMP), ethnic spices (ES), and cosmetic products (CP). Comparison analyses were carried out using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). In general, results reported for Cd, Cu and Pb by the XOS prototype analyzer, and based on the instrument's non-metal mode, were negatively biased (5 % to 95 %) compared to ICP-OES. In contrast, results reported for Pb, As, Cd, Cu and Zn by the Niton, based on using the soil mode, were positively biased, in some instances (Cd) by up to 4 orders of magnitude. While the sensitivity of both instruments was insufficient for reliably "quantifying" toxic elements below 15 mg/kg, XRF was still capable of positively "detecting" many elements at the low single digit mg/kg levels. However, for semi-quantification estimates of contaminants at higher levels, and with limited sample preparation, both XRF instruments were deemed fit for the purpose. This study demonstrates that modern XRF instrumentation is valuable for characterizing the elemental content of food, cosmetic, and medicinal products. The technology is particularly useful for rapidly screening large numbers of products (100s per day) in the field, and quickly identifying those that may contain potentially hazardous levels of toxic elements. Toxic elements can be confirmed by examining the raw spectrum, and the limitations of factory-based calibration are generally manageable for field-based studies.

Pharmacokinetic properties of arsenic species after oral administration of Sargassum pallidum extract in rats using an HPLC-HG-AFS method

Sargassum pallidum is one of the Traditional Chinese Medicine widely used for phlegm elimination and detumescence. Arsenic is present in high concentration in seaweed belonging to the genus Sargassum. Therefore, the consumption of S. pallidum is a route of exposure to arsenic. Since the toxicity of arsenic is highly dependent on its chemical speciation, the determination of total arsenic is not adequate to assess the risks. Here, a high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) was developed for determination of the common arsenic species including arsenite [As(III)], dimethylarsinate (DMA), methylarsonate (MMA) and arsenate [As(V)] simultaneously. This method was applied to study the pharmacokinetic profile of these arsenic species in rats after oral administration of S. pallidum extract at different doses. The described assay was validated for limit of quantification, linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability according to the FDA validation guidelines. As(III) or MMA was not detected in any samples collected at all time points using the present HPLC-HG-AFS method. As(V) and DMA in the S. pallidum could be readily absorbed and eliminated in rats. A trend of dose-dependence was shown for DMA and As(V) in the drug concentration-time profiles. This study would be helpful for the apprehension of the action mechanism and clinical application of medicinal seaweeds.

Monitoring of arsenic levels in some ready-to-use anti-malaria herbal products from drug sales outlets in the Madina area of Accra, Ghana

In Ghana anti-malaria herbal medicines or products are used to compliment commercial drugs in treatment and prevention of Plasmodium falciparum infections. In this study, four common aqueous based anti-malaria herbal products (coded HEB, KFE, MDM and NIB) which are used by Ghanaian population from pharmacy/herbal stores in the Madina area, Accra were blindly and randomly sampled for cadmium (Cd), arsenic (As) and Lead (Pb) analysis using Atomic Absorption Spectrophotometry technique. Arsenic concentrations were 1.087 μg/mL (108.7%), 1.027 μg/mL (102.7%), 0.330 μg/mL (33.0%) and 0.274 μg/mL (27.4%) in MDM, KFE, NIB and HEB respectively. Arsenic concentration determined in MDM and KFE were above the maximum permissible limit of 1.0 ppm determined by WHO/FAO. Cadmium concentration in each of the four products as well as lead concentration in KFE, NIB and HEB were below the detection limit of <0.002 mg/mL (Cd) and <0.005 mg/mL (Pb) respectively. The maximum permissible limits for Pb and Cd determined by WHO/FAO are 10.0 ppm and 0.3 ppm respectively. Thus, random assessment on the safety of some ready-to-use aqueous based anti-malaria herbal products on the market is necessary to prevent public health hazards associated with consuming these plant extracts. Although lead and cadmium concentration in the anti-malaria herbal products were below the maximum permissible limits, their cumulative effect on the health of an individual which consume recommended volume of not less than 1000 mL for effective malaria parasite clearance cannot be ignored.