Tea Fluoride Research Articles

Drinking brick tea containing high fluoride increases the prevalence of osteoarthritis in Tibetan, China

ABSTRACT The prevalence of osteoarthritis (OA) in Tibetans is higher than that in Han, while Tibetans have a habit of drinking brick tea with high fluoride. A cross-sectional study was conducted to explore the association between fluoride exposure in drinking brick tea and OA. All subjects were divided into four groups by the quartiles (Q) of tea fluoride (TF) and urine fluoride (UF). ROC was plotted and OR were obtained using logistic regression model. The prevalence of OA in the Q3 and Q4 group of TF were 2.2 and 2.7 times higher than in the Q1 group, and the prevalence of OA in the Q2, Q3 and Q4 group of UF were 3.2, 3.5, and 4.1 times higher than in the Q1 group. ROC analysis showed the cutoff values were 4.523 mg/day (TF) and 1.666 mg/L (UF). In conclusion, excessive fluoride in drinking brick tea could be a risk factor for developing OA.

Assessment and health risk of fluoride from Northeast Indian tea (Camellia sinensis L.): Fixing up the maximum residue level of fluoride in tea

The tea plant is considered a strong fluoride (F-) hyperaccumulator plant. We have proposed the Maximum Residue Limit (MRL) of F- in tea based on 321 tea samples collected from 8 tea-growing regions of Northeast India. Total F- as well as water-soluble F- content was analysed through the ion selective electrode with the recovery percentage of 100–108 to ascertain the risk associated with F- towards human health. It has been observed that total F- contents (mg kg−1) in Cachar, Darjeeling, Dooars, North Bank, South Bank, Terai, Tripura, and Upper Assam ranged from 42.5 to 111.5, 16.0 to 168.0, 48.0 to 291.0, 36.5 to 314.0, 60.0 to 154.0, 26.5 to 233.5, 26 to 118 and 44 to 244, respectively. The F- content in tea infusion varied between 1.08 mg L−1 and 2.43 mg L−1 across all eight regions with a mean of 1.90 mg L−1. The average transfer of F- from made tea (processed young shoot of tea plants comprising a bud and 2 to 3 leaves) to tea infusion was 100.46%. Fluoride content in infusion was decreased with the increment of infusion number but increased gradually with continuous infusion time. The non-carcinogenic health risk was assessed. Calculated Hazard Quotient values were far below 1. The calculated and rounded MRL (300 mg kg−1) was recommended for F- in tea in India.

Selenium foliar application contributes to decrease ratio of water-soluble fluoride and improve physio-biochemical components in tea leaves

The tea plant accumulates elevated levels of fluoride (F) from environmental sources. Drinking tea containing high F levels poses a potential threat to human health. Selenium (Se) was applied by foliar spray to investigate its effects on F accumulation and physiology in tea plant. Foliar application of different forms of Se, i.e., Na2SeO3, Kappa-selenocarrageenan, Selenomethionine and Nanoselenium, reduced F content in tea leaves by 10.17 %−44.28 %, 16.12 %−35.41 %, 22.19 %−45.99 % and 22.24 %−43.82 %, respectively. Foliar spraying Se could increase F accumulation in pectin through increasing pectin content and pectin demethylesterification to bind more F in the cell wall, which decreased the proportion of water-soluble fluoride in tea leaves. Application of Se significantly decreased the contents of chromium (39.6 %−72.0 %), cadmium (48.3 %−84.4 %), lead (2.2 %−44.4 %) and copper (14.1 %−44.6 %) in tea leaves. Foliar spraying various forms of Se dramatically increased the Se content and was efficiently transformed into organic Se accounting for more than 80 % in tea leaves. All Se compounds increased peroxidase activity by 3.3 %−35.5 % and catalase activity by 2.6 %−99.4 %, reduced malondialdehyde content by 5.6 %−37.1 %, and increased the contents of chlorophyll by 0.65 %−31.8 %, carotenoids by 0.24 %−27.1 %, total catechins by 1.6 %−21.0 %, EGCG by 4.4 %−17.6 % and caffeine by 9.1 %−28.6 %. These results indicated that Se application could be served as a potential efficient and safe strategy diminishing the concentration of F in tea leaves.

Fluoride and Aluminium in Tea (Camellia sinensis L.)-Tea Quality Indicators and Risk Factors for Consumers.

In recent years, the quality and sourcing of tea have gained importance in Europe, but information remains scarce. The aim of this study was to determine the concentrations of fluoride (F-) and total aluminium (Al) species in infusions of commercially available teas in Slovenia, and thus in Europe, and to relate them to tea quality and their impact on consumer safety. F- concentrations were determined using a fluoride-ion-selective electrode and Al concentrations using inductively coupled plasma optical emission spectroscopy. A comparison of the results obtained for four selected tea samples using the calibration curve and a standard addition technique showed good agreement, with no interferences caused by the sample matrix. The concentrations of 35 commercial teas ranged from 0.34 to 4.79 and 0.51 to 8.90 mg/L for F- and Al, respectively. The average concentrations of the two elements followed the same descending order: black filter > green filter > black leaves ≈ green leaves. Single and multivariate statistical methods supported the categorisation of teas by packaging but not by type, with tea in filter bags being more expensive than loose tea. The linear relationship between F- and Al concentrations in infusions (C(Al) = 1.2134 · C(F-)) allows for the determination of one element and estimation of the other, leading to a significant reduction in laboratory effort and cost. This research advances tea assessment by proposing Al concentration alongside F- as a quality indicator and provides the basis for tea-monitoring protocols. Finally, the daily consumption of larger quantities of tea (≈1 L) with elevated F- and Al concentrations could potentially pose a health risk.

Biochar addition to tea garden soils: effects on tea fluoride uptake and accumulation

Long-term consumption of tea with high fluoride (F) content has a potential threat to human health. The application of different amounts of biochar to reduce F accumulation in tea leaves has been little studied. In this study, a pot experiment was conducted to investigate the effect of biochar amounts (0, 0.5%, 2.5%, 5.0%, 8.0%, and 10.0%, w/w) on tea F content during the tea plant growth. Changes in tea quality, soil F fraction, and soil properties caused by biochar and the relationship with tea F accumulation were also considered. The results showed that the application of biochar amendment significantly reduced water-soluble F contents in tea leaves compared to CK (without biochar), especially in the 8.0% treatment (72.55%). Overall, biochar contributed to improving tea polyphenols and caffeine, but had no significant impact on free amino acids and water leachate. Compared with CK, 5.0–10.0% biochar significantly increased soil water-soluble F content due to the substitution of F− with OH− under high pH. Additionally, biochar applied to tea garden soil was effective in decreasing the soil exchangeable aluminum (Ex-Al) content (46.37–91.90%) and increasing the soil exchangeable calcium (Ca2+) content (12.02–129.74%) compared to CK, and correlation analysis showed that this may help reduce F enrichment of tea leaves. In general, the application of 5.0–8.0% biochar can be suggested as an optimal application dose to decrease tea F contents while simultaneously improving tea quality.Graphical

Fluoride content in various types of tea used by tea stalls in Salem district - An in vitro cross sectional study.

Tea leaves are natural rich source of fluoride and are known as fluorine absorbants. It is consumed on large scale in India and thus needs to be monitored for its daily fluoride consumption by customers. Tea manufacturers should mention fluoride concentrations on the packages to avoid overdose through unknown consumption by consumers. To detect the levels of fluoride in tea at different periods of boiling and to compare the fluoride levels in various brands of tea at different periods of boiling. A survey was conducted in 25 tea stalls of Salem on the type of tea and time of boiling black tea. The five most common brands of tea will bought for the study. The stainless-steel vessel will be used in the methodology for boiling tea. Mettur water will be used for the preparation of black tea and 1 g of tea leaves to 100 ml of hot (~95°C) deionized water (1% w/v tea infusion) and allowed the mixture to stand for 5 min in a glass beaker. After 5 min, the infusions were filtered and again left standing until they are cooled to room temperature. All fluoride measurements will be completed within 4 h of the preparation of the infusion. About 2 min and 4 min boiling will be followed. The fluoride present in each brand of tea will be calculated from black tea prepared using 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene-disulfonate (SPADNS) calorimetric method. The distribution of mean score of fluoride level in tea powders available in tea shops of Salem when boiled in distilled water was (559.00 ± 112.12). The mean score of fluoride level in tea powders available in tea shops of Salem boiled in Mettur water was (689.05 ± 116.34). To test the significance of difference between the average fluoride in tea powders available in tea shops of Salem when boiled in distilled water and Mettur water, the independent t-test was used. the P value is <0.05, and hence, it is found that there is significant difference between the average fluoride in tea powders available in tea shops of Salem boiled in distilled water and Mettur water. Thus, the study showed tea consists of significant amount of fluoride concentration that is consumed on daily basis. The study also evaluated fluoride concentration in tea preparations using different water. The study shows necessity for regulations of mentioning fluoride concentration on tea packs.

Comprehensive assessment of water quality and associated health risks in an arid region in south Iran

This study aims at investigating the quality of drinking water and evaluating the non-carcinogenic risk of fluoride and nitrate ions in drinking water, and fluoride in tea in Zarrin Dasht, Iran. We focus on tea since it is the most popular drink among Iranian people and in the study region. We collected and analyzed 23 drinking water samples and 23 tea samples from different locations in the study region. Based on the water quality index, the consumed drinking water does not have a good quality in most Zarrin Dasht areas. Accordingly, the water quality index (WQI) is poor and very poor in 70% and 13% of the water samples, respectively. The average fluoride concentration of the tea samples is 2.71 mg/L. The mean values of Fluoride Hazard Index (HIfluoride) are 3.77, 2.77, and 2.33 for children, teenagers, and adults, respectively, which are higher than the safe limit of 1. The Nitrate Hazard Index (HInitrate) is higher than the safe limit of 1 in 8.7% of the samples. The results of the Monte Carlo simulation demonstrate that HIfluoride and HInitrate are higher than 1 in all the groups, except for adults. According to the results of the sensitivity analysis, ingestion rate and body weight have a large effect on HIfluoride and HInitrate, but body weight is inversely associated with sensitivity. According to the Piper diagram, saline water is the predominant type in Zarrin Dasht. Besides, the results of the principal component analysis (PCA) show a high correlation between fluoride and pH, which could be related to the effect of pH on fluoride dissolution and ion exchange. Therefore, appropriate measures are recommended to be taken in order to reduce the amount of fluoride in the drinking water resources of this region. Reduction of tea consumption can also be considered an important factor in decreasing the amount of fluoride intake.

The Effect of Phosphate Fertilizer on Fluoride Accumulation in Tea Leaves Based on Ecological Environment Analysis

Moderate levels of fluoride ingestion are beneficial to human health. Tea plant can accumulate fluoride. The high intake of fluoride may lead to skeletal fluorosis and dental. When the usage of phosphate fertilizer increased, the water soluble fluoride contents in the soil increased and the soil pH values decreased. The fluoride contents in the green teas were linearly related with the water soluble fluoride contents in the soil. The phosphate fertilizer, which contained high levels of fluoride, led to the high fluoride contents in the mature green teas. In developing green chemistry and green engineering, it maybe a low-cost method for the reduction the contents of fluoride in mature teas by limiting on the fluoride content in phosphate fertilizer used in the tea plantations in China.

Determination of fluoride in tea leaves and tea infusions by ion selective electrode

A fluoride ion selective electrode method for the determination of fluoride contents in tea leaves and tea infusions was set up. Using commercial timothy grass powder and tea leaf powder as standard materials, this method demonstrated linearity between 0.02 and 2.00 mg/L of fluoride with R2 greater than 0.999. Both materials had coefficient of variations (CV, %) less than 3%, indicating good reproducibility in the determinations. The recovery tests of tea infusions spiked with different amounts of sodium fluoride demonstrated 94-107% of recovery with CV less than 1.2%, indicating that the method is very accurate. With 1% of tea leaves to boiling water ratio, up to 63-78% of fluoride in tea leaves could be released into tea infusion by repeated infusions and 82-83% by continuous infusion. By this method, total fluoride contents of 12 brands of tea leaves purchased from Nantou County were determined to be 100-451 mg/kg dry weight, and those of their infusions in boiling water for a 5-min period were determined to be 0.39-1.21 mg/L. Assuming that daily tea infusions drinking for an adult is 2 L, fluoride intake from tea infusions of these tea leaves is far below the daily fluoride tolerable upper limit 10 mg.

SKlotho is associated with the severity of brick tea-type skeletal fluorosis in China

The change of serum soluble Klotho (sKlotho) content is related to a variety of osteoarthropathy. However, its association with the severity of skeletal fluorosis (SF) is not clear. Here, the association of tea fluoride exposure with serum sKlotho levels and the severity of SF were investigated and further verified in a rat model of fluorosis. A cross sectional case control study was conducted in residents over 50 years old from brick-tea drinking areas in Qinghai and Xinjiang Provinces, China. Concentrations of fluoride in brick tea water and urine were determined by ion selective electrode method, and the levels of serum sKlotho were determined by ELISA method. Linear regression and ordered logistic regression models were constructed to examine the relationship among fluoride exposure, serum sKlotho levels and the severity of SF. The kidney and small intestine of Wistar rats were isolated for detection of Klotho by immunohistochemistry (IHC), and femoral artery blood was sampled to measure the serum levels of sKlotho. An increase of 1 mg/day in tea fluoride intake (TFI) was associated with a 12.070 pg/mL (95% CI: 0.452–23.689) increase in serum sKlotho levels and a 1.163-fold (95% CI: 1.007–1.342) increase in the severity of SF after adjusting for age, gender, and ethnicity. Serum sKlotho levels were also positively associated with the severity of SF (P < 0.05). The mediation analysis showed that serum sKlotho levels mediated 17.76% of the increase in the severity of SF caused by an increase of 1 mg/day of TFI. Moreover, a significant increase of serum sKlotho levels in fluoride-exposed groups was also seen in the rat model. The present study suggests that serum sKlotho may be a potential mediator of SF in brick tea-type fluorosis endemic areas.

Two New Members of CsFEXs Couple Proton Gradients to Export Fluoride and Participate in Reducing Fluoride Accumulation in Low-Fluoride Tea Cultivars.

The accumulation of fluoride in tea leaves from various cultivars exhibits significant differences. However, the molecular basis and mechanism remain largely unknown. Here, we reported that two genes of CsFEX (fluoride export genes in Camellia sinensis), CsFEX1 and CsFEX2, transport fluoride out of cells, alleviate the cellular fluoride toxin, and rescue the yeast mutant (FEX1ΔFEX2Δ) and Arabidopsis mutant (fex), as their efflux activities are coupled with proton gradients. Further analysis found that CsFEX1 and CsFEX2 localize to the plasma membrane both in yeast and Arabidopsis cells. CsFEX2 is more effective to reduce fluoride toxicity in yeast and Arabidopsis compared with CsFEX1 even at low pH. CsFEX2 induced by fluoride treatment is around tenfold higher in a low-fluoride cultivar (Yunkang 10) than that in a high-fluoride cultivar (Pingyang Tezaocha), suggesting that CsFEX2 possibly plays a critical role in reducing fluoride accumulation in tea leaves.

Risk assessment of fluoride daily intake from preference beverage

Background/purposeTea, coffee and alcohol beverages are called preference beverage and are drunk habitual and in large quantities. Therefore, there is a high possibility that a health risk is caused by the contained components, and risk assessment of intake is essential. However, the risk assessment of fluoride intake from preference beverages has not been sufficiently performed. Materials and methodsThis study estimated the daily fluoride intake from preference beverages by measuring the fluoride concentration of infusion liquid and measuring the total fluoride content by the microdiffusion method. In addition, Hazard Quotient (HQ) was calculated for children and adults to assess the risk of fluoride intake. ResultsAs a result of this study, tea was the highest in all sample species, the infusion of tea was 1.06–6.68 mg/L and the total fluoride content of tea was 47.05–291.98 mg/kg. Green tea showed the next highest value, 0.26–4.09 mg/L, 21.91–83.68 mg/kg. Herbal tea fluoride levels were 0.07–0.17 mg/L and 0.05–1.90 mg/kg, Unique tea was 0.03–0.60 mg/L and 0.03–32.37 mg/kg, Coffee was 0.03–0.15 mg/L and 0.04–0.64 mg/kg. ConclusionThe HQ values calculated from the average daily fluoride intake (DFI) of preference beverages were all within the safe range. Some products made from Camellia sinensis, such as tea and green tea, had 1.66 mg/day as DFI at maximum, and the Child's HQ exceeded 1. These results suggest that habitual consumption of some products requires risk management of dental fluorosis.

Fluoride in tea from Shandong Province, China and exposure assessment

ABSTRACT In this study fluoride in 170 tea samples from Shandong province (China) was determined using a selective ion electrode. The fluoride concentrations ranged from 31.2 to 338 mg/kg with an average of 119 mg/kg. The mean fluoride concentrations were 164, 121, 98.7 and 96.8 mg/kg, which corresponded to Pu’erh tea, green tea, oolong tea and black tea, respectively. Moreover, 4.7% of the analysed samples exceed the legal limit of 200 mg/kg recommended by China. The estimated daily intake of fluoride via drinking tea for an adult was between 0.655 and 1.07 mg/person/day, which were lower than the provisional maximum tolerable daily intake value of 3.5 mg/person/day set by the National Health and Family Planning Commission of the People’s Republic of China. In future, maintaining a surveillance programme to monitor the trend of fluoride in tea is necessary for food safety and human health.

Tea components influencing bioavailability of fluoride and potential transport mechanism in the Caco‐2 cell line model

SummaryPrevious work showed that the bioavailability of fluoride in dark tea was lower than NaF solution. However, limited information is available indicating the effects of tea components on the fluoride bioavailability. In this study, the effects of the components in tea on the bioavailability of fluoride were evaluated in the Caco‐2 cell line model. Additionally, the mechanism of effect of aluminium on fluoride transport was investigated. The result showed that 10–100 μm of epigallocatechin gallate (EGCG) could not influence fluoride transport. Al3+ significantly decreased fluoride transport in both apical‐basolateral and basolateral‐apical directions. Moreover, aluminium could form different forms of aluminium fluoride complexes, which were transported through Caco‐2 cells by different pathways. F− transport was mainly dependent on the paracellular pathway and active transport involving Cl− channels. The paracellular pathway played a predominant role in transport of AlF3. The paracellular pathway and active transport both participated in AlF2+ transport.

Comparison of Fluoride Ion Concentration in Black, Green and White Tea

Back ground: Tea is one of the most commonly used drinks in the world. Drinking too much tea might affect the health. Tea is known for its fluoride resources; hence, consuming tea especially together with other fluoride resources can increase the risk of appearance of dental fluorosis. Considering the unspecified concentration of fluoride in white tea in Iran, the current study has carried out to evaluate the concentration of fluoride in different types of black tea, green tea and white tea of Refah Factory of Lahijan. Method and Material: In this study, the content of the fluoride of the black, green and white teas were measured. One gram samples of each type of tea were provided. Each time, the samples were placed in 200 milliliters of boiling distilled water, then it was moved to 80 degrees of Celsius incubator to be brewed. After 5 and 15 minutes, the solution was filtered. Concentration of the fluoride was measured through chromatography method and was recorded by measure of milligrams per liter. Data were analyzed using SPSS21 software. And significant level of less than 0.05 was considered. Findings: The concentration of the fluoride of the black, green and white solutions at the time of 5 minutes of brewing were respectively 1.38, 1.07 and 0.18 milligrams per liter and significantly increased he concentration of fluoride in all three types of tea with increasing drainage time (p value&lt;0.05). Conclusion: The concentration of the fluoride of the three tea types were significantly different, to the extent that the least fluoride concentration belonged to the white and the most concentration belonged to black tea at both brewing times. By increasing the time of brewing the tea, its concentration was increased.&#x0D;

Enhanced fluoride adsorption of aluminum humate and its resistance on fluoride accumulation in tea leaves

ABSTRACTTea trees (Camellia sinensis) can take in fluorine from soil and the content of fluorine in tea increases with maturity, leading to high content of fluoride in tea leaves and tea products. Long-term consumption of high fluoride tea products could result in chronic fluoride intoxication. Confining the fluoride in the earth with absorbents to reduce the fluoride accumulation of the tea trees during the growth period which could radically control the fluoride level in tea product. Humic acid (HA), a kind of organic matter in the earth was used as raw material to prepare adsorbent aluminum humate (HAA) by aluminum modification. The HAA absorbent presented excellent absorption performance to the fluoride in a wide pH range (4–10), and the maximum adsorptive capacity can reach to 62.5 mg/g. The absorption isotherm demonstrated the adsorption of fluoride was the monomolecular adsorption and the absorption was in accordance with the pseudo-second order kinetic equation. Fluoride content in real soil solution decreased significantly by 53.03% by using the HAA absorbent. The utilization of HAA adsorbent in the culture and field plots experiments also obviously adsorb the soluble fluoride in solution and soil, which could significantly suppress the fluoride accumulation in tea leaves. In September, the fluoride accumulation in tea leaves has been reduced 74.29% in the field plots experiments.

FRZB1 rs2242070 polymorphisms is associated with brick tea type skeletal fluorosis in Kazakhs, but not in Tibetans, China.

Skeletal fluorosis is a metabolic bone and joint disease caused by excessive accumulation of fluoride in the bones. Compared with Kazakhs, Tibetans are more likely to develop moderate and severe brick tea type skeletal fluorosis, although they have similar fluoride exposure. Single nucleotide polymorphisms (SNPs) in frizzled-related protein (FRZB) have been associated with osteoarthritis, but their association with the risk of skeletal fluorosis has not been reported. In this paper, we investigated the association of three SNPs (rs7775, rs2242070 and rs9288087) in FRZB1with brick tea type skeletal fluorosis risk in a cross-sectional case-control study conducted in Sinkiang and Qinghai, China. A total of 598 individuals, including 308 Tibetans and 290 Kazakhs, were enrolled in this study, in which cases and controls were 221 and 377, respectively. The skeletal fluorosis was diagnosed according to the Chinese diagnostic criteria of endemic skeletal fluorosis (WS192-2008). The fluoride content in tea water or urine was detected using the fluoride ion electrode. SNPs were assessed using the Sequenom MassARRAY system. Binary logistic regressions found evidence of association with rs2242070 AA genotype in only Kazakh participants [odds ratio (OR) 0.417, 95% CI 0.216-0.807, p = 0.009], but not in Tibetans. When stratified by age, this protective effect of AA genotype in rs2242070 was pronounced in Kazakh participants aged 46-65 (OR 0.321, 95% CI 0.135-0.764, p = 0.010). This protective association with AA genotype in rs2242070 in Kazakhs also appeared to be stronger with tea fluoride intake > 3.5mg/day (OR 0.396, 95% CI 0.182-0.864, p = 0.020). Our data suggest there might be differential genetic influence on skeletal fluorosis risk in Kazakh and Tibetan participants and that this difference might be modified by tea fluoride intake.

TMT-based quantitative proteomics analysis reveals the response of tea plant (Camellia sinensis) to fluoride

The tea plant is a fluoride hyperaccumulator, and fluoride accumulation in its leaves is closely related to human health. To dissect molecular mechanisms underlying fluoride accumulation/detoxification, the leaves of tea seedlings exposed to different fluoride treatments for 30 days were sampled for physiological and proteomics analyses. The results showed that fluoride had no adverse effects on the growth of tea seedlings in spite of high content fluoride accumulation in their leaves. Through TMT coupled with UPLC MS/MS, 189 differentially accumulated proteins were quantified, of which 41 and 148 were localized in the cell wall and cellular compartments respectively. 41 cell wall proteins were mainly conductive to cell wall structure rearrangement, signaling modulation and the protection cells from damages; 148 cellular compartments proteins mainly contributed to diverse metabolisms reprogramming, energy reallocation and plant defense. Notably, upregulation of several proteins including GHs, smHSPs, DRT100, YLS2-like, primary amine oxidase, GDSL esterase/lipases and citrate synthase probably enhanced the defense of tea seedlings against fluoride. Collectively, our results presented a comprehensive proteomics analysis on the leaves of tea seedlings in response to fluoride, which would contribute to further deciphering of molecular mechanisms underlying fluoride accumulation/detoxification in tea plant. SignificanceThe tea plant (Camellia sinensis) is an important economic crop with its made tea occupying up the third non-alcohol beverage in the world. Tea plant is also a fluoride hyperaccumulator with up to 98% fluoride accumulation in the leaves by initiative absorption. Due to the fact that about 40% to 90% of fluoride could be readily released into tea infusion and then absorbed by human body, overaccumulation of fluoride in tea leaves is closely related to human health. Therefore, it is very necessary to deeply dissect the mechanisms underlying fluoride accumulation/detoxification in tea plant.Previously, numerous studies were conducted to investigate fluoride specification and fluoride localization of tea plant at morphological, physiological and biochemical levels, which documented that fluoride was majorly immobilized in the cell walls and stored in the vacuoles in the form of fluoride-ligands complexes. However, the molecular mechanisms governing cell wall immobilization and vacuolar compartmentation of fluoride were still remaining unknown. Thus, a quantitative proteomics study into the leaves of tea seedlings upon exposure to fluoride was performed in current study. Our results showed that 41 and 148 of 189 differentially accumulated proteins were targeted into the cell wall and cellular compartments respectively, revealing that cell wall proteins and cellular compartments proteins played crucial roles in the response of tea seedlings to fluoride. Our results were also in good agreement with the idea that the cell wall was involved in fluoride accumulation/detoxification in tea plant. However, the functions of key interested differentially accumulated proteins need be further analyzed in follow-up work.

Fluoride concentrations in traditional and herbal teas: Health risk assessment

Traditional tea (Camellia sinensis) and herbal tea are being consumed across the world. However, long term consumption of tea can increase the chances of fluorosis owing to the presence of fluoride (F) in teas. Therefore, it is imperative to assess the health risk associated with tea consumption. The main objectives of this study were to: 1) estimate total F in 47 popular teas, including traditional and herbal teas and F concentrations in 1% (w/v) infusion of 5 min, and 2) assess the exposure risks of F from tea consumption in children and adults. The data showed that total F was the least in herbal teas (33–102 mg/kg) and their infusions (0.06–0.69 mg/L) compared to traditional teas (296–1112 mg/kg) and their infusions (1.47–6.9 mg/L). During tea infusion, 6–96% and 18–99% of the F was released into the water from herbal and traditional teas, respectively. Ten samples of traditional teas, including five green teas had chronic daily intake (CDI) values of F > 0.05 mg/d/kg bw, the stipulated permissible limits of F intake from all sources. Although the F from teas posed no immediate health hazards with hazard quotient <1, some tea samples could potentially contribute >4 mg F/d, thereby adding to the overall F burden. Therefore, together with F from food and water sources, daily F consumptions from teas might increase its health risks to humans. So, caution should be excised when drinking teas containing high F.

Safety Evaluation of Fluoride Content in Tea Infusions Consumed in the Azores-a Volcanic Region with Water Springs naturally Enriched in Fluoride.

Tea is the second most commonly consumed beverage in the world. It is well recognized that the consumption of tea in high quantities can promote the development of fluorosis. The main objective of this study is to estimate the exposure to fluoride in the Azores through drinking tea prepared with water from different volcanic locations, by i) investigating the fluoride (F) content of various commercial brands of tea (Camellia sinensis) marketed in Azores and ii) comparing tea releasing rates of F according to brewing time, considering the fluoride concentration in the different types of water used for the infusion. Fluoride contents were determined by ion-selective electrode in 30 samples of drinking water from three different locations and in 450 samples of tea (black and green tea) from three different brands. Fluoride concentration in water ranged from 0.29 to 1.56ppm (Porto Formoso and Sete Cidades village, respectively). Fluoride concentrations increased with brewing time, reaching the highest values in the Azorean black and green tea infusions. For all the studied brands, a negative correlation was found between tea fluoride contents and the pH of the water used to prepare the infusion. Fluoride concentration in infusions was significantly associated with the background fluoride concentration in drinking water. Since the fluoride concentration in groundwater varies accordingly to the geological conditions and tea consumption can contribute to fluoride intake, it is important to define the limits for tea consumption, particularly in fluoride-rich areas. Graphical Abstract Fluoride concentrations in black and green tea for 3 minutes of brewing time and, association between fluoride concentration and pH with brewing time.