Estimation of heavy metals in commonly used medicinal plants: a market basket survey

Polycyclic aromatic hydrocarbon (PAH) accumulation in selected medicinal plants: a mini review

The use of plant-based products in healthcare systems has experienced a tremendous rise leading to a substantial increase in global demand. However, the quality and effectiveness of such plant-based treatments are often affected due to contamination of various pollutants including polycyclic aromatic hydrocarbons (PAHs). Like other plants, medicinal plants also uptake and accumulate PAHs when exposed to a contaminated environment. The consumption of such medicinal plants and/or plant-based products causes negative effects on health rather than providing any therapeutic advantages. Unfortunately, research focusing on PAH accumulation in medicinal plants has received very limited attention. This review discusses a sizable number of literature regarding the concentration of sixteen priority PAH pollutants as recognised by the US Environmental Protection Agency (USEPA) in different medicinal plants. The review also highlights the risk assessment of cancer associated with some medicinal plants in terms of benzo[a]pyrene (BaP) equivalent concentrations.

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.

The Safety Assessment of Toxic Metals in Commonly Used Herbs, Spices, Tea, and Coffee in Poland

The presented study was aimed at the determination of the level of contamination with heavy metals (Cd, Pb, As, and Hg) in 240 samples of plant materials, i.e., herbal raw materials, spices, tea, and coffee. Moreover, a probabilistic risk assessment (noncarcinogenic and carcinogenic risks) was estimated by models including target hazard quotient (THQ) and cancer risk (CR). The samples were subjected to microwave mineralisation with the use of HNO₃ (65%), while the determination of the content of the elements was performed with the use of inductively coupled plasma mass spectrometer (ICP–MS) and a mercury analyser. The element which was characterised by the highest level of accumulation in the analysed samples was lead (from 0.010 to 5.680 mg/kg). Among the heavy metals under analysis, the lowest concentration was noted in the case of mercury (from 0.005 to 0.030 mg/kg). A notably higher level of contamination with heavy metals was noted in the analysed samples of herbs and spices (0.005–5.680 mg/kg), compared to samples of tea and coffee (0.005–0.791 mg/kg). According to the guidelines of the World Health Organisation (WHO) concerning the limits of contamination of samples of herbal raw materials with heavy metals, lead levels exceeding the limits were only noted in 24 samples of herbs (18%). In all of the analysed samples of spices, tea, and coffee, no instances of exceeded limits were noted for any of the analysed heavy metals. The values of TTHQmax (in relation to the consumption of the analysed products) were as follows: up to 4.23 × 10⁻² for spices, up to 2.51 × 10⁻¹ for herbs, up to 4.03 × 10⁻² for China tea, and up to 1.25 × 10⁻¹ for roasted coffee beans. As the value of THQ ≤1, there is no probability of the appearance of undesirable effects related to the consumption of the analysed group of raw materials and products of plant origin. The CR value for As (max. value) was 1.29 × 10⁻⁵, which is lower than the maximum acceptable level of 1 × 10⁻⁴ suggested by United States Environmental Protection Agency (USEPA).

Determination of the Cadmium, Chromium, Nickel, and Lead Ions Relays in Selected Polish Medicinal Plants and Their Infusion

Concentration of Cd, Cr, Ni, and Pb were determined in peppermint leaves (Folium Menthae piperitae), chamomile blossom (Anthodium Chamomillae), and their infusions by atomic absorption spectrometry (AAS) after microwave digestion of plants samples. Peppermint and chamomile preparations by five different producers were purchased at various pharmacies in Poland. Infusions were made from herbs according to prescription for patients, provided by the producer of medicine on the package. Results show that in exam of medicinal plants the content of cadmium exceeds World Health Organization (WHO) standards. The highest level of extraction was observed for Ni (50-70% of the total content in herb), Cr (28-36%), Cd (14-16%), and the lowest for Pb (about 6%). The calculated daily intake all analyzed elements was very low. Phytotherapy with using of these herbs is safe for health of patient even in case of long time therapy.

Toxicity Potential of Nutraceuticals

By the turn of the twenty-first century, the use of nutraceuticals became increasingly popular in both humans and animals due to their easy access, cost-effectiveness, and tolerability with a wide margin of safety. While some nutraceuticals are safe, others have a toxic potential. For a large number of nutraceuticals, no toxicity/safety data are available due to a lack of pharmacological/toxicological studies. The safety of some nutraceuticals can be compromised via contamination with toxic plants, metals, mycotoxins, pesticides, fertilizers, drugs of abuse, etc. Knowledge of pharmacokinetic/toxicokinetic studies appears to play a pivotal role in safety and toxicity assessment of nutraceuticals. Interaction studies are essential to determine efficacy, safety, and toxicity when nutraceuticals and therapeutic drugs are used concomitantly. This chapter describes various aspects of nutraceuticals, particularly their toxic potential, and the factors influencing their safety.

The Hazard Content of Cadmium, Lead, and Other Trace Elements in Some Medicinal Herbs and Their Water Infusions

54 samples belonging to 23 herbal species (15 individuals and 8 mixtures) were analyzed for their contents of heavy metals in the raw materials and in their water infusions. Trace and toxic elements in these samples were determined by using inductively coupled plasma-atomic emission spectrometry (ICP-OES) following acid digestion. The order of decreasing mean metal concentrations in raw materials (mg/kg) was found to be as follows: Fe (440) > Mn (162) > Zn (45.8) > Cu (12) > Pb (10.4) > Ni (5.4) > Cr (2.9) > Co (0.91) > Cd (0.5). It was found that 21% of the analyzed samples contain both Cd and Pb above their permissible limits. However, the infusions produced from these plants were found to contain fewer amounts of metals than the raw materials. Studied metals had the following mass transfer percentages to the infusion solutions (Fe: 3.5%, Cd: 14%, Cr: 15%, Pb: 20%, Co: 29%, Ni: 31%, Zn: 36%, Cu: 48%, and Mn: 53%). The estimated daily intake calculated for the toxic elements Pb and Cd through the consumption of herbal infusions was far below the tolerable daily intake set by the World Health Organization (WHO).

Heavy metals translocation and accumulation from the rhizosphere soils to the edible parts of the medicinal plant Fengdan (Paeonia ostii) grown on a metal mining area, China

Fengdan (Paeonia ostii) is one of Chinese 34 famous medicinal materials. This study investigated the concentrations of Arsenic (As), Chromium (Cr), Cadmium (Cd), Copper (Cu), Lead (Pb), Iron (Fe), Manganese (Mn), and Zinc (Zn) in rhizosphere soils, cortex mouton and seeds of Fengdan planted in a metal mining area, China. The mean concentrations of As, Cd, Cu, and Zn in the rhizosphere soils were above the limits set by the Chinese Soil Environmental Quality Standard (GB 15618-1995). The contamination factor (CF) of Cd was >5, while it was >2for As, Cu, Pb, and Zn in all the soils. The integrated pollution index for all the soils was >3 and ˂ 5. Metal concentrations in the edible parts of Fengdan were in the following decreasing order: Mn>Fe>Zn>Cu>Pb>As>Cr≥Cd. The transfer factor mean values for As, Cu, Cd and Fe in the cortex moutan of old Fengdan (over 6 years) were significantly higher than in young Fengdan. Available metal concentrations, pH and soil organic matter content influenced the metal concentrations of the cortex moutan. The results indicated that mining and smelting operations have led to heavy metals contamination of soils and medicinal parts of Fengdan. The major metal pollutants were elemental Cd, Cu, Pb, and Zn. Heavy metals mainly accumulated in the cortex moutan of Fengdan. The mean concentrations of Cd, Cu, and Pb in the old cortex moutan (over 6 years) were above those of the Chinese Green Trade Standards for Medicinal Plants and Preparations in Foreign Trade (WM/T2-2004).

Evaluation of Potentially Toxic Metal Contamination of Local Medicinal Plants and Extracts Sold in Ibadan, Nigeria

BACKGROUND

Extracts from medicinal plants have been widely used in the treatment of public health ailments, however, medicinal plants may be grown in polluted soil/water environments. Many of these plants are harvested and processed by local and illiterate natural healers and other vendors in an unhygienic manner. This results in the possibility of contamination with potentially toxic metals from the environment.

OBJECTIVES

This study evaluated the concentrations of lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni), copper (Cu) and zinc (Zn) in 25 samples of different medicinal plants procured from stores in open markets in Ibadan, Nigeria.

METHODS

After procurement, the samples were air dried, pulverized and dry ashed. All ashes were dissolved with dilute acid solutions, filtered and the filtrates were stored for metal analysis. Samples with elevated metal concentrations were extracted with water and alcohol solutions to mimic the medicinal extracts obtained from these plants. Metal concentrations were analysed in all extracts and filtrates using atomic absorption spectrophotometry.

RESULTS

Metal concentrations (mg/kg dry weight) in all samples ranged as follows: Cu, 0.04 - 9.44; Zn, 0.36 - 35.4 and Pb, below detection limits (BDL) - 6.15. The concentrations of Cd, Cr and Ni in all samples were BDL. The concentrations of all metals in the samples were within accepted limits set for medicinal plants according to international regulatory bodies. All ethanol extracts and 1 out of 4 water extracts contained Pb.

CONCLUSIONS

Medicinal plants could pose chronic metal toxicity effects from continual bioaccumulation along the food chain. Furthermore, extraction of active ingredients with water was deemed to be safer than the use of alcohol extracts. Continuous monitoring of these medicinal plant materials is needed.

Gaultheria trichophylla (Royle): a source of minerals and biologically active molecules, its antioxidant and anti-lipoxygenase activities

BACKGROUND

Gaultheria trichophylla (Royle) is used as food and for treating many ailments in folk medicine especially against inflammation. The purpose of this in vitro study was to evaluate the ability of extracts of G. trichophylla as anti-oxidant and anti-inflammatory agent and for its mineral contents.

METHODS

Powdered plant material (100 g) was extracted with 100 ml each of methanol, chloroform, and n-hexane using soxhlet extractor. Antioxidant activity of methanol extract was assessed by DPPH radical scavenging and FRAP assays. Determination of enzyme inhibition activity was determined using 5-LOX inhibitory activity. Total phenolic and flavonoids contents were measured by Folin-Chicalteu and colorimeteric methods respectively. Minerals and heavy metals contents were determined using Atomic absorption spectrophotometer. Qualitative HPLC analysis were performed using some standard phenolic compounds.

RESULTS

The highest phenolic (17.5 ± 2.5 mg GA equivalent/g) and flavonoids (41.3 ± 0.1 mg QE equivalent/g) concentrations were found in methanol extract, which also showed more scavenging activity of 1, 1-diphenyl-2-picrylhydrazyl and ferrous reducing power with IC50 = 81.2 ± 0.2 and IC50 = 11.2 ± 0.1 μg/ml, respectively. The methanol and chloroform extracts showed best inhibition of 5-lipoxygenase enzyme with 90.5 ± 0.7% and 66.9 ± 0.1% at 0.5 mg/ml, respectively. G. trichophylla extract was also evaluated for mineral contents (K, Na, Ca, Mg, Fe, and Cu), and for chemical profiling of heavy metals (Cr, Pb, Cd, Co, Zn, Ni and Hg).

CONCLUSION

Our current findings suggest that this plant is good source of minerals and concentration of all heavy metals were within permissible limits. The results revealed that this ignored plant has great pharmaceutical and nutraceutical potential.

Evaluation of Trace Metal Profile in Cymbopogon validus and Hyparrhenia hirta Used as Traditional Herbs from Environmentally Diverse Region of Komga, South Africa

FAAS was used for the analysis of trace metals in fresh and dry plant parts of Cymbopogon validus and Hyparrhenia hirta species with the aim of determining the trace metals concentrations in selected traditional plants consumed in Eastern Cape, South Africa. The trace metal concentration (mg/kg) in the samples of dry Cymbopogon validus leaves (DCVL) showed Cu of 12.40 ± 1.000; Zn of 2.42 ± 0.401; Fe of 2.50 ± 0.410; Mn of 1.31 ± 0.210; Pb of 3.36 ± 0.401 mg/kg, while the samples of fresh Hyparrhenia hirta flowers (FHHF) gave Cu of 9.77 ± 0.610; Zn of 0.70 ± 0.200; Fe of 2.11 ± 0.200; Mn of 1.15 ± 0.080; Pb of 3.15 ± 0.100 mg/kg. Abundance of metal concentrations follows the order: Cu > Fe > Pb > Mn > Zn in the flower samples of Cymbopogon validus and Hyparrhenia hirta species. The concentrations of trace metals in both plant parts were below the permissible limits (PL) set by WHO. It is suggested that pharmacovigilance be carried out periodically to improve the quality, safety, and efficiency of various herbal products.

New perspectives on dietary-derived treatments and food safety-antinomy in a new era

Despite the advances in science and technology and wide use of chemical drugs, dietary intervention (or food therapy) remains useful in preventing or treating many human diseases. A huge body of evidence shows that the dietary pattern or habit is also an important contributing factor to the development of chronic diseases such as hypertension, type 2 diabetes, hyperlipidemia, and cancers. In recent years, over-the-counter health foods, nutraceuticals, and plant-derived medicinal products have been gaining popularity all over the world, particularly in developed countries. Unfortunately, owing to the contamination with various harmful substances in foods and the presence of toxic food components, food-borne diseases have also become increasingly problematic. Incidents of food poisonings or tainted food have been increasing worldwide, particularly in China and other developing countries. Therefore, the government should put in a greater effort in enforcing food safety by improving the surveillance mechanism and exerting highest standards of quality control for foods.

Multi-elemental profiling and chemo-metric validation revealed nutritional qualities of Zingiber officinale

Ginger rhizome is a valued food, spice and an important ingredient of traditional systems of medicine of India, China and Japan. An Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) based multi-elemental profiling was performed to assess the quantitative complement of elements, nutritional quality and toxicity of 46 ginger germplasms, collected from the north western Himalayan India. The abundance of eighteen elements quantified in the acid digested rhizomes was observed to be K>Mg>Fe>Ca>Na>Mn>Zn>Ba>Cu>Cr>Ni>Pb>Co>Se>As>Be>Cd. Toxic element, Hg was not detected in any of the investigated samples. Chemometric analyses showed positive correlation among most of the elements. No negative correlation was observed in any of the metals under investigation. UPGMA based clustering analysis of the quantitative data grouped all the 46 samples into three major clusters, displaying 88% similarity in their metal composition, while eighteen metals investigated grouped into two major clusters. Quantitatively, all the elements analyzed were below the permissible limits laid down by World Health Organization. The results were further validated by cluster analysis (CA) and principal component analysis (PCA) to understand the ionome of the ginger rhizome. The study suggested raw ginger to be a good source of beneficial elements/minerals like Mg, Ca, Mn, Fe, Cu and Zn and will provide platform for understanding the functional and physiological status of ginger rhizome.

Investigation of heavy metals in frequently utilized medicinal plants collected from environmentally diverse locations of north western India

The increasing prevalence of environmental pollution, especially soil contamination with heavy metals has led to their uptake in the human food chains through plant parts. Accumulation and magnification of heavy metals in human tissues through consumption of herbal remedies can cause hazardous impacts on health. Therefore, chemical profiling of nine heavy metals (Mn, Cr, Pb, Fe, Cd, Co, Zn, Ni and Hg) was undertaken in stem and leaf samples of ten medicinal plants (Acacia nilotica, Bacopa monnieri, Commiphora wightii, Ficus religiosa, Glycyrrhiza glabra, Hemidesmus indicus, Salvadora oleoides, Terminalia bellirica, Terminalia chebula and Withania somnifera) collected from environmentally diverse regions of Haryana and Rajasthan states in North-Western India. Concentration of all heavy metals, except Cr, was within permissible limits in the tested stem and leaf samples. Leaf samples had consistently more Cr compared to respective stem samples with highest concentration in leaf samples of Bacopa monnieri (13.19 ± 0.0480 ppm) and stem samples of Withania somnifera (4.93 ± 0.0185 ppm) both collected from Bahadurgarh (heavy industrial area), Haryana. This amount was beyond the permissible limit of 2.0 ppm defined by WHO for raw herbal material. Other two most perilous metals Pb (2.64 ± 0.0260) and Cd (0.04 ± 0.0274) were also recorded in Bahadurgarh region, although below permissible limits. Concentration of Hg remained below detectable levels in all the leaf and stem samples tested. These results suggested that cultivation of medicinal plants and other dietary herbs should be curtailed near environmentally polluted especially industrial areas for avoidance of health hazards.

Chemical and Physical Methods to Analyze a Multicomponent Traditional Chinese Herbal Prescription Using LC-MS/MS, Electron Microscope, and Congo Red Staining

This study develops several chemical and physical methods to evaluate the quality of a traditional Chinese formulation, Jia-Wei-Xiao-Yao-San. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with electrospray ionization was used to measure the herbal biomarkers of saikosaponin A, saikosaponin D, ferulic acid, and paeoniflorin from this herbal formula. A scanning electron microscope (SEM) and light microscopy photographs with Congo red staining were used to identify the cellulose fibers if raw herbal powder had been added to the herbal pharmaceutical product. Moreover, water solubility and crude fiber content examination were used to inspect for potential herbal additives to the herbal pharmaceutical products. The results demonstrate that the contents of the herbal ingredients of saikosaponin A, saikosaponin D, ferulic acid, and paeoniflorin were around 0.351 ± 0.017, 0.136 ± 0.010, 0.140 ± 0.005, and 2.281 ± 0.406 mg/g, respectively, for this herbal pharmaceutical product. The physical examination data demonstrate that the raw herbal powder had rough, irregular, lumpy, filamentous, and elongated shapes, as well as strong Congo red staining. In addition, water solubility and crude fiber content were not consistent in the herbal pharmaceutical products.

Evaluation of metal concentrations in mentha herbal teas (Mentha piperita, Mentha pulegium and Mentha species) by inductively coupled plasma spectrometry

Phytopharmaceuticals are gaining popularity worldwide; however, cases of adverse effects and drug interactions have also increased. One reason is in the high metal content both as ingredients but also as contaminants. Metal monitoring in food, like herbal teas, provides basic information on safety aspects in regulatory processes as well as nutritional values. In the present work, Cd, Pb, K, Na, Ca, Mg, Al, B, Ba, Co, Cr, Cu, Fe, Mn, Zn, Li, Ni, and Mo were determined by inductively coupled plasma spectrometry (ICPS) in 36 samples of Mentha sp. Mint tea bags and loose leaves were randomly obtained from supermarkets, traditional markets, herbal stores, and pharmacies in Tenerife (Canary Islands, Spain). Metal contents varied significantly, dependent on the stores the products were purchased in and on tea packaging (loose leaves versus tea bags). Pb analyses revealed levels (0.65±0.71mg/kg) below legal limits. The maximum permissible limit for Cd, 0.3mg/kg, set by the WHO for medicinal plants, was exceeded by 19.44% of the samples (0.22±0.13mg/kg), but all values were below the limit given in the European Pharmacopoeia for this metal (4mg/kg). We observed high Al (151.24±162.73mg/kg) and Li (5.46±3.94mg/kg) levels. B, Ba, Co, Cr, Cu, Fe, Mn, Ni, Zn, and Mo mean levels were 20.51, 14.15, 0.26, 1.65, 10.65, 406.00, 55.05, 1.72, 33.67, and 0.73mg/kg, respectively. Mean Ca, Mg, K, and Na were detected in concentrations of 10.32, 3.83, 7.23 and 1.17g/kg, respectively. In conclusion, metal exposure through herbal mint teas does not seem to be of health concern, as to most of the studied metals, but regulatory limits for Al contents should be imposed.

Monitoring of mercury, arsenic, cadmium and lead in Ayurvedic formulations marketed in Delhi by flame AAS and confirmation by ICP-MS

The quality and safety of Ayurvedic formulations has become a serious issue, as this Indian system of medicine is used by 80% of the Indian population. Hence, the present study was performed to evaluate heavy metals contents by flame atomic absorbance spectroscopy (AAS) measurements and confirmation by inductive coupled plasma-mass spectroscopy (ICP-MS). A total of 78 formulations (56 herbal, 19 herbometallic and 3 metallic) were sampled. In herbal formulations, lead in 19.6% (11/56), cadmium in 21.4% (12/56), mercury and arsenic in 5.3% (3/56) were above the limit. Lead in 52.6% (10/19) of samples, cadmium in 26.3% (5/19) and mercury and arsenic contained in one herbometallic sample was above the limit. Heavy metals in all metal formulations were above the WHO limit. Significant batch variation was observed. The analytical results of flame AAS and ICP-MS did not differ significantly in the range of measurements in this study, which proves that both methods are satisfactory for estimation of heavy metals in these type of samples.

Lead content in pot marigold (Calendula officinalis L.) inflorescences and leaves: impact of precipitations and vicinity of motorway

Trace metal contamination is a major environmental and health problem virtually in all countries. The present study was aimed to estimate the lead content of pot marigold (Calendula officinalis L.) inflorescences and leaves collected from a nonpolluted test field. The lead content in dry pot marigold inflorescences was 9.34 ± 0.79 µg/g, in dry leaves 11.57 ± 0.47 µg/g, and in soil 0.649 ± 0.012 µg/g. The distance of pot marigold collection beds (30-220 m from the motorway) had no effect on lead content. There was a strong positive correlation between the amount of precipitations and lead content of pot marigold leaves but not inflorescences indicating the soil as primarily the source of increased lead content. In conclusion, no effect of motorway vicinity was found for pot marigold inflorescences or leaves lead content; however, as a precaution, it is not recommended to collect the plants during or just after showers.

Accumulation of heavy metals in selected medicinal plants

In this review, we evaluate the reports published between 1993 and 2011 that address the heavy metal accumulation in 88 medicinal plant species. We compare the safe limits for heavy metals set by governmental agencies vs. the levels at which such metals actually exist in selected medicinal plants. We also evaluate the uses and effectiveness of medicinal plants in health care, and assess the hazards of medicinal plant uses, in view of the growing worldwide use of medicinal plants. From our extensive review of the literature, we discovered that a maximum permissible level (MPL) of Pb is exceeded in 21 plant medicine species, Cd in 44 species, and Hg in 10 species. Vetiveria zizanioides a potential candidate species for the treatment of cardiovascular diseases absorb a wide range of heavy metals from metal-contaminated soils. We believe that this species is the single most impressive example of a potentially hazardous medicinal plant. Based on our review, we endorse the hypothesis that heavy metal accumulation by medicinal plants is mainly caused by extraction of soluble metals from contaminated soil, sediments and air. One continuing problem in protecting consumers of plant-based medicines is that permissible levels of all heavy metals in herbal medicine have not yet been standardized by regulating governmental entities. Moreover, there are few limit tests that exist for heavy metal content of medicinal plants, or permissible limits for essential dietary minerals, in most medicinal plants. The dearth of such limits hamstrings development of medicinal plant research and delays the release of either new or improved versions of medicinal plants or their components. In the present review, we emphasize that medicinal plants are often subjected to heavy metal contamination and that the levels at which these heavy metals sometimes occur exceeds permissible levels for some species. Therefore, collecting medicinal plants from areas that are, or may be, contaminated should be discouraged and banned if possible.

Volatile (As and Hg) and non-volatile (Pb and Cd) toxic heavy metals analysis in rhizome of Zingiber officinale collected from different locations of North Western Himalayas by Atomic Absorption Spectroscopy

Ginger is an important ingredient of spice and herbals. The monitoring of toxic heavy metals in the rhizome of ginger is important for protecting public health against the hazards of metal toxicity. The concentration of volatile and non-volatile metals (As, Hg, Pb and Cd), in the soil and rhizome of Zingiber officinale were analyzed using AAS. Soil analysis profile showed uniformity in the metal contents, in active root zone and subsoil, except mercury, which was present in higher quantity in one, out of the four sectors, of the field. The infield metal content in the soil in increasing order was, cadmium < arsenic < lead < mercury. In ginger rhizome the volatile toxic heavy metals arsenic (As) and mercury (Hg) varied from not detected to 0.13 μg/g and 0.01 to 0.42 μg/g, respectively. The non-volatile metals lead (Pb) and cadmium (Cd) ranged from 0.06 to 0.64 μg/g and 0.002 to 0.03 μg/g, respectively(.) The results illustrated the findings that soil is the major but not the only source of metal accumulation in the plants. In our study, the volatile metal content (As, Hg) was found more in rhizomes collected from Himachal Pradesh while the non-volatile metals were predominant in samples from Uttarakhand.