Study of Heavy Metals in Teas from Romanian Market

The aim of this study was to determine heavy metals levels in some varieties of tea from the Romanian market. For this purpose, 15 samples of tea of the following assortments were analyzed: green tea, black tea, herb tea and fruit tea. Determination of heavy metals traces was achieved with inductively coupled plasma mass spectrometry (ICP-MS). The quantities of Pb, Hg and Cd from analyzed tea samples were compared with the permissible dose in accordance with the Notice of Scientific Panel on Contaminants in the Food Chain of European Food Safety Authority (EFSA).

about 160 cups. The secret of this extraordinary tea generalization is that the nature has concentrated in the leaves a variety of substances, each of them useful for the body, with subtle flavors and pleasant taste.
The legislation in Romania does not provide maximum limits for heavy metals in tea assortments, but only for total mineral content as in Table 1. Knowing the quantities of heavy metals in soft drinks and teas shows a great importance, especially in summer, when the body requires an intense moisturizing. Many plants are components of dietary supplements, so they bring in their composition an amount of heavy metals that will add to that of their essential components [24]. Metal pollutants are usually non degradable and a homeostasis mechanism of discharging them from the human body is not known, so the high level of heavy metals endanger the biological life [9].
In accordance with the Notice of Scientific Panel on Contaminants in the Food Chain of European Food Safety Authority (EFSA), the permissible dose of Cd is 7μg/kg body/daily, of Pb 25μg/kg body/daily, and of Hg is 1,6μg/kg body/daily.

Experimental part Materials and methods
The research was carried out in order to identify and dose heavy metals in various samples of tea. Samples were purchased from the Romanian market, totalling 15 assortments in the form of bags, from various companies, Table 2. Determination of heavy metals Determination of heavy metals traces is achieved with mass spectrometry inductively coupled with plasma ICP-MS, Agilent Technologies 7500 Series. Samples preparation is carried out in accordance with SR EN ISO 14082:2003-Determination of trace elements by atomic absorption spectrometry after ashing. Dissolving ash obtained from the calcination is performed using high purity reagents (HNO3, Merck, Germany, Suprapur grade).
Concentration (C) of heavy metals in samples obtained is expressed in µg/g sample and is calculated with the formula [26]: where: a -concentration value measured by the device, [ppb]; V -volume of acid that dissolved the sample [ml]; m -mass of mineralized sample [g]. Determination of samples humidity by method of drying in oven. The sample is dried in an oven under an air stream at atmospheric pressure and at a temperature of 110-130°C to a constant weight. Depending on the mass loss is calculated humidity sample, in percent for each sample.
Determination of ash content of tea assortments by means of calcination at 550-600°C. The ash is the amount of minerals after calcination, non combustible residue that remains from the test sample.

Results and discussions
Data analysis shows that C11 samples tea are rich in heavy metals such as Pb, Ni, Cd, Hg, Co, and in essential elements such as Zn and Ag (true antiseptic), which, however, in large amounts can become toxic to the body [27]. Chinese green tea (C4 samples) contains high amounts of As, Bi and U235. C1, C7, C10, C14 tea samples are rich in Ce and Sn. C2, C5, C6, C13 samples (green tea, black tea, rosehip, calendula) have predominant metals as Al, Cr, Fe, Co, U235 and U238. C9 and C15 tea samples have the lowest amount of heavy metals and minerals.
Results from Table 3 present the characterization of tea assortments according to the content of heavy metals. Principal Component Analysis was performed with the software Unscrambler X 10.1 according to the humidity content, ash and mineral concentrations in different samples of tea. This analysis identifies the assortments of teas chemically similar. Principal component analysis was performed to assess the overall effect of chemical composition on the origin of teas.
In Figure 1 and In Figure 1 there is an agglomeration of types of tea in one group, only two types of tea are not grouped with the others, the two types are Chamomile tea (C7) and linden tea (10) due to the much higher concentration of Mg in the two teas against the other teas examined. The location of linden tea at the top of PC1 is due to the concentration of Sn.
Both Mg and Sn are the parameters that significantly influence the variation (their distribution in Figure 2 shows them at a greater distance from origin located on the left side; the parameters on the left side of the component PC2 have a greater influence than those located to the right side of the component). Figure 2 shows that Zn, Li, Cd and Ag concentrations are situated close to the origin of the coordinates, indicating that these parameters are not useful in the total variance. PC1 distinguishes the samples according to the content of Ce and U238, while PC2 distinguishes samples according to the content of Se, Au and Sn.

Conclusions
Teas are considered to be small chemical laboratories because the plants which are so useful for their effects on the body in some situations, concentrate essentially thousands of substances still unknown.
After grouping the various teas, the analysis showed that C11 tea samples are the richest in metals such as Pb, Ni, Cd, Hg, Co. The quantities of Pb and Hg from analyzed samples do not represent a threat to health, even if consumed in the desired amount, because in accordance with the European Food Safety Authority (EFSA) the permissible dose is 25μg Pb/kg body/daily respectively 1.6 μg Hg/kg body/daily.
Regarding the cadmium content, some samples have a higher quantity than the permissible dose such as: 2.72 times for Chamomile tea (C7), 4.05 times for Goat Weed tea (C1) and of 5.96 times for Gentian tea (C11) even for a single tea bag. For others tea assortments the consumption can be 2-10 tea bags without exceeding the permissible dose of 7μg Cd/kg/daily (considered for an average body weight of 70 kg).
From the analyzed data of tea samples and taking into consideration the permissible doses for heavy metals according to EFSA, except the three teas with a high content in Cd: Goat Weed (C1), Chamomile (C7) and Gentian (C11), the other teas can be appreciated without health risk even if consumed in the desired amount.  Figure 1 there is an agglomeration of types of tea in one group, only two types of tea are not grouped with the others, the two types are Chamomile tea (C7) and linden tea (10) due to the much higher concentration of Mg in the two teas against the other teas examined. The location of linden tea at the top of PC1 is due to the concentration of Sn.

Fig. 2. Distribution of chemical compounds in tea
Both Mg and Sn are the parameters that significantly influence the variation (their distribution in Figure 2 shows them at a greater distance from origin located on the left side; the parameters on the left side of the component PC2 have a greater influence than those located to the right side of the component). Figure 2 shows that Zn, Li, Cd and Ag concentrations are situated close to the origin of the coordinates, indicating that these parameters are not useful in the total variance. PC1 distinguishes the samples according to the content of Ce and U238, while PC2 distinguishes samples according to the content of Se, Au and Sn.

Conclusions
Teas are considered to be small chemical laboratories because the plants which are so useful for their effects on the body in some situations, concentrate essentially thousands of substances still unknown.
After grouping the various teas, the analysis showed that C11 tea samples are the richest in metals such as Pb, Ni, Cd, Hg, Co. The quantities of Pb and Hg from analyzed samples do not represent a threat to health, even if consumed in the desired amount, because in accordance with the European Food Safety Authority (EFSA) the permissible dose is 25μg Pb/kg body/daily respectively 1.6 μg Hg/kg body/daily.
Regarding the cadmium content, some samples have a higher quantity than the permissible dose such as: 2.72 times for Chamomile tea (C7), 4.05 times for Goat Weed tea (C1) and of 5.96 times for Gentian tea (C11) even for a single tea bag. For others tea assortments the consumption can be 2-10 tea bags without exceeding the permissible dose of 7μg Cd/kg/daily (considered for an average body weight of 70 kg).