Health risks from consumption of medicinal plant dietary supplements

Abstract The aim of this study was to determine the heavy metal contents of dietary supplements manufactured from medicinal plants and assess the potential daily burden on their consumers. The study consisted of 41 dietary supplements produced from terrestrial plants or microalgae. The analysis of cadmium, lead, and mercury content was performed using analytical methods. The content of Cd and Pb was determined by flame atomic absorption spectrometry (FAAS). The mercury content was determined using atomic absorption spectrometry with the generation of cold mercury vapor (CVAAS). The presence of at least one of the three analyzed heavy metals was found in 79.2% samples of supplements produced from terrestrial plants and in 88.2% supplement samples produced from microalgae. Hazard quotient was used to calculate noncarcinogenic risk for humans by ingestion of dietary supplements containing heavy metals. From among all supplements, 68.3% of samples were contaminated with Cd and Pb (this does not always apply to the same samples) and 29.3% of samples were contaminated with Hg. The health risk assessment of consumers of dietary supplements showed, in an extreme case, that taking this supplement for only one week poses a health risk associated with exposure to Pb. The health risk associated with the intake of dietary supplements primarily depends on the duration of consumption.

supplement (tablets, capsules, drops, liquid, or powder) and their most common place of distribution, that is, pharmacies, may mislead the consumer and suggest their association with medicine.
In many European countries, including Poland, in case of dietary supplements, there is no need for statutory requirement regarding continuing supervision of their security (EP, 2002). The idea of taking food supplements is not to cure diseases. The goal is to lower the consequences of risk factors influencing the consumer on everyday basis and may cause the disease development. Since those supplements do not cure, it is hard to predict the side effects of their usage.
Currently, society's knowledge of dietary supplements is primarily channeled through the marketing displays of products. With the dynamically evolving markets for dietary supplements, especially in the last decade, public awareness of their possible harm is very slim. In 2015, dietary supplement market was worth € 0.8 billion in Poland. According to Industry Report, in the next 5 years the market will be progressing by 8% per year, and by the year 2020, it will have exceeded €1.2 billion (IR, 2017).
Until recently, mostly health-promoting components like vitamins, minerals, or amino acids could be found in dietary supplements.
Currently, they can also contain raw materials of plant and herbal origin or their extracts (Filipiak-Szok, Kurzawa, & Szłyk, 2015). Food supplements on the base of plants, not only available in pharmacies, but also herbal stores or via Internet retailers may be contaminated with toxic elements. Thus, they could become an additional source of absorption of such elements by the human body. Significant amounts of heavy metals, especially Cd and Pb in some of the herbaceous plants, can propagate from their growth in high-intensive traffic or industrialized areas (Socha & Borawska, 2011). In some special circumstances, the use of supplements may be necessary and advisable. However, over-usage, leisurely consumption, or exposure to higher than the recommended allowable intake can cause toxicity and pose serious health threats (Korfali, Hawi, & Mroueh, 2013).
Despite the worldwide use of botanical products and increase in popularity, the WHO found that among the 191 listed countries, only 25 had a national policy regarding herbals and only 64 regulated them (Avigan, Mozersky, & Seeff, 2016). Polish dietary supplement market responsible for nutrition safety is known to be improperly monitored.
According to the State Control (Kotynia, Szewczyk, & Tuzikiewicz-Gnitecka, 2017), Poland does not offer the right security of dietary supplements to its citizens and quality of products was not effective either.
The primary aim of this study was to determine the Cd, Pb, and Hg contents in dietary supplements based on the type of plants (terrestrial or microalgae) from which they are produced. Our secondary goal was to assess the potential daily heavy metal burden on their consumers.

| Product Selection and Sampling
The study material consisted of 41 dietary supplements, available on the Polish market, produced from terrestrial plants (24 samples) or from microalgae (17 samples (EC, 2007). Samples for testing were collected under the official control of the trade, in a manner that would ensure the representativeness of the lot. To determine the content of lead and cadmium, the size of the single sample was 5-15 g, depending on the type of product. The size of an individual sample to determine the content of mercury was 1-7 g depending on the type of product. The implementation and analysis of all the above-mentioned factors in creating a sampling plan for research are to ensure the representativeness of the results.
All sample material delivered to the laboratory was used to prepare the laboratory sample. As far as possible, during sample preparation, the apparatus and equipment in contact with the sample did not contain metals and were made of an inert material, for example, plastic (polypropylene-PP, polytetrafluoroethylene-PTFE) or glass, and were washed with acid to minimize the risk of contamination. In the sample preparation, the procedures described in the EN 13,804:2013 standard were used (CEN, 2013).

| Analytical methods
The analysis of Cd, Pb, and Hg content was performed at the ac-  Blind reagent samples were prepared in parallel with samples tested under the same conditions without the addition of a matrix to take into account contaminants from the solutions and reagents used.

| Human health risk assessment
The where.
-ADD is the average daily potential dose of heavy metal through ingestion (mg/kg day -1 ); -C is the metal content in the food product (mg/kg); -IR is the ingestion rate (kg/day); -EF represents the exposure frequency (365 days -1); -ED is the exposure duration (70 years);  -BW is the body weight (70 kg); -AT represents the average exposure time (EF x ED). and the hazard quotient (HQ) were calculated (Tables S5, S7, and S9, in Appendixes). In the second scenario group, it was assumed that the consumer was taking the maximum recommended dose stated on the package, but the duration of usage was allowed to vary. In this scenario group, we considered four cases of two weeks (scenario IV), one month (scenario V), two months (scenario VI), and three months (scenario VII) exposure, respectively (Tables S6, S8, and S10, in Appendixes). For the purpose of risk assessment, exposure period of two weeks was assumed to be the shortest since that is normally the period that one package of the supplement lasts, although there is evidence to show that in general, consumers use supplements for longer periods of time. where.
-HI is the hazard index for chronic exposure to heavy metals 1 through i, unitless -HQ i is the hazard quotient for the ith heavy metal, where all i heavy metals are assumed to affect the same target organ or organ system, unitless.
As with the HQ, an HI value less than or equal to 1 indicates that the exposure is not likely to result in adverse noncancer effects.
According to US EPA, an HI value greater than 1, however, does not necessarily suggest a likelihood of adverse health effects and cannot be interpreted as a statistical probability of adverse effects occurring.

| Concentrations of Cd, Pb, and Hg in Dietary Supplements
In the current study, samples were coded according to whether they were produced from terrestrial plants (TP) or from microalgae (M). Hg (0.94 mg Cd/kg and 0.03 mg Hg/kg) was determined in two terrestrial plant supplements, respectively, in TP15 and TP20 (Table 1). in the analyzed supplements produced from terrestrial plants ranged from < Limit of Detection (< LOD) -0.9 mg/kg, from < LOD -3.7 mg/ kg, and from < LOD -0.03 mg/kg, respectively. In case of supplements produced from microalgae, the minimum and maximum values of analyzed heavy metals amounted: < LOD -0.4 mg/kg for Pb, < LOD -0.08 mg/kg for Cd, and < LOD -0.02 mg/kg for Hg (Table 2).

| Health Risk Assessment
The associated risk presented in this study was based on two kinds of scenarios of exposure from dietary supplements (Tables S5 -S10, in Appendixes). The first group included three scenarios in which ADD and HQ were estimated depending on the adopted dose of individual supplements by consumers. The risk assessment based on HQ = ADD∕RfD HI = HQ 1 + HQ 2 + … +HQ i the first three scenarios was measured given the consumption of a dietary supplement during one day, but in the first scenario as the concentrations of Cd, Pb, and Hg, the MPCs for these elements were given (EC, 2006(EC, , 2008(EC, , 2011(EC, , 2014. The second and third scenarios took into account the actual contents of the analyzed heavy metals in all supplements. However, the differentiating factor was the maximum dose of supplement recommended by the producer to achieve the desired health effect (scenario II) and twice the maximum dose (scenario III) (Tables S5, S7, and S9, in Appendixes). In the second group, there were four scenarios in which ADD and HQ were estimated depending on the period of consumption of dietary supplements (scenarios IV-VII) (Tables S6, S8, and S10, in Appendixes). The period of consuming the dietary supplement was analyzed, from two weeks (for most supplements, two weeks is the period during which one package is used) to two and three months (it is the average time of consuming dietary supplements in Poland (SAO, 2016)). In each scenario, the highest daily average dose (ADD) was estimated for all three metals, taking into account the maximum dose of analyzed supplements recommended by the producers. The HQ for Cd and Pb for each dietary supplement in the three scenarios, and for mercury in scenarios I to IV, were found below 1, which indicates safe with no risk to human health. Higher than 1 HQ value for Cd was estimated for dietary supplement from Poland no. TP15 (cistus) in scenarios IV-VII (HQ was from 1.9 to 11.3), and in two Chinese products-in sample no. TP20 in VI and VII scenarios (HQ was from 1.1 to 1.6) and TP22 in scenario VII (HQ = 1.4). It means that consuming this dietary supplement in the maximum recommended dose for just two weeks for TP15, 2 months for TP20, and 3 months for TP22 may pose a noncarcinogenic risk of consumers health (Table 3). The assessment of the health risk to consumers of dietary supplements related to Pb contents showed a significant risk for four Chinese supplements: TP20, TP22, TP23, and TP24 and for sample M13 (spirulina, from Poland) with an intake period of at least 2 weeks for TP20 (HQ was from 2.1 to 12.6), 4 weeks for TP22 (HQ was from 1.8 to 5.3), 4 weeks in case of TP23 (HQ was from 1.2 to 3.7), 2 months in case of TP24 (HQ was from 1 to 1.5), and 3 months in case of M13 (HQ = 1.1) ( Table 3). Estimation of exposure to mercury has shown HQ over 1 in 5 samples, for example, in TP17 from Albania (HQ = 1.1), TP20 (HQ = 1.9-2.9), TP22 (HQ = 1.2-3.6), and two samples from Poland-M9 (HQ = 1) and M13 (HQ = 1.5) ( A thorough investigation by Kotynia et al. (2017)  grapeseeds. Another group of supplements worth mentioning is oils made of primrose seeds, flax, pumpkin seeds, and sea buckthorn (Czajkowska, 2006). Although there are many advantages of diet of plant origin, there appear to be some doubts among researchers as to whether frequent usage of such substances is safe for consumers. Those questions surface due to lack of information of a proper quality regarding long-term effects on health, ergo allergic In terms of dietary supplements, from the point of view of public health, the problem is their potential pollution, including heavy metals. Cadmium (Cd), being one of the most dangerous environmental pollutants, is extremely hazardous due to the fast absorption of it by living organisms and the tendency to accumulate in plant and animal tissues (Kaczyńska, Zajączkowski, & Grzybiak, 2015). The transfer of Cd, adsorbed by plants, may be caused by leaking sewage sludge to agricultural soil. That may play a significant role in food chain, and then accumulate in various human organs (Rahimzadeh, Rahimzadeh, Kazemi, & Moghadamnia, 2017). Cd is mostly being absorbed through the root system, but also through the leaves.
Collection of that metal is happening through a competition with other ions (e.g., potassium, calcium, magnesium) for the place in membrane transporters. Therefore, Cd is carried easily and a permanent and systematic binding of metal in the human cell can occur (Gambuś & Rak, 2000). If Cd accumulates in a human body and in the food chain, it can lead to acute and chronic intoxications. Noticeable effects on health are diarrhea, stomach pains, bone fracture, reproductive failure, and even possibly infertility, in addition to damage to the central nervous system, immune system, and psychological disorders. The transformation of normal epithelial cells into carcinogenic cells due to inhibiting the biosynthesis of protein is also caused by Cd (Gambuś & Rak, 2000). The most common effects in humans and animals include damage to the liver, lung, kidneys, and causing anemia, osteoporosis, and a wide range of tumors (Kaczyńska et al., 2015). the body can have a negative influence on Nervous System and as a result of chronic risk-damage of the kidneys and liver (Flora, Gupta, & Tiwari, 2012;Seńczuk, 2005). Pb may also affect pregnancy-it crosses the placenta and has been confirmed to be the reason for intrauterine death, prematurity, and low birthweight (Papanikolaou, Hatzidaki, Belivanis, Tzanakakis, & Tsatsakis, 2005). Mercury (Hg) and most of its compounds are toxic and became environmental pollutants. Protracted poisoning may lead to disorders of   (Chary, Kamala, & Raj, 2008;Jolly, Islam, & Akbar, 2013;Rattan, Datta, Chhonkar, Suribabu, & Singh, 2005).
Therefore, here we adopt the same measure to assess the health risk associated with exposure to heavy metals contained in dietary supplements. Although the HQ-based risk assessment method does not provide a quantitative estimation for the probability of an exposed population experiencing a negative health effect, it factually provides an indication of health risk level due to exposure to pollutants such as heavy metals (Jolly et al., 2013;Jamal et al., 2013). Therefore, overdosing of this type of products is quite common since there is a belief that herbal products and supplements do not pose any health threats. In addition, combination of different drugs and supplements poses a risk not only in terms of interactions between chemicals in different preparations but also because of heavy metals entering the body from other sources. Consumers should pay more attention to the consumption of dietary supplements and be aware of the negative effects they can cause. To enhance the safety of dietary supplement consumers, it seems necessary to implement a stricter quality control and determine safe dosing regimens. In addition, authorities allowing supplements for human consumption risk should implement assessment analysis before the introduction of the supplement on the market.
Analysis of the results also showed that the amount of heavy metal concentrations in the tested dietary supplements may depend on the place of origin of the product. However, the form of the supplement (powder, tea bags, tablets) and the type of the main ingredient (terrestrial plants, microalgae) have less influence on the differentiation of heavy metal content in the product (Table 1).
There is a need for a legislative action to stabilize the current situation. For example, a system could be introduced warning the user that the product has not been tested by the authorities. Also, there could be a regulating procedure to withdraw a flawed supplement from the market or suspend the distribution of doubtful products.
Due to the soaring number of plant-based supplements on the market, their detailed analysis for public health security and possible toxicity is necessary.

| CON CLUS IONS
1. Dietary supplements show contamination with heavy metals; cadmium was found in 68% of all analyzed samples, lead in 68%, and mercury in 29%.
2. The concentration of heavy metals depends on the country where the dietary supplement was produced. Less important seemed to be form (powder, tea bags, tablets) and whether or not the base ingredient was microalgae or terrestrial plant.
3. The health risk associated with the intake of dietary supplements primarily depends on the duration of consumption.
4. It is suggested that pharmaceutical companies should include information on the recommended duration of consumption, determined from risk assessment analysis.

| E THI C AL G U IDELINE S
Ethics approval was not required for this research.

CO N FLI C T O F I NTE R E S T
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.