Wednesday, December 11, 2013

Commercially Available Teas "Not Suitable For Human Consumption": Potentially Hazardous Amounts of Lead, Aluminum, Arsenic & Co in Every Cup

Would all commercially available teas have to be labeled like this?
I am usually not a fan of articles with titles like this one (see above) - they have what you call in Germany "Bildzeitungsniveau" (the German tabloid with news like "World about to disappear in a black hole, when CERN starts operating). It is however hard to resist the urge to use a headline like the one above, if the it fits the results of peer-reviewed scientific paper so well, as it is the case with the relatively recent paper from the University of Alberta and the Luleâ University of Technology in Sweden this SuppVersity article is (almost) all about.

The corresponding experiment, the results of which were published in the peer-reviewed open-access Journal of Toxicology in October 2013, already, addresses the increasing concern about contamination of foodstuffs and natural health products. With the emphasis being on foodstuff and health, it's only logical that tea, or more precisely all currently available off-the-shelf varieties of black, green, white, and oolong teas sold in tea bags were used for analysis in the said study.

So what did the researchers do?

Schwalfenberg, Genius (no joke, the 2n author is a real 'Genius by name') and Rodushkin conducted a three-step analysis in the course of which they analyzed the content of previously identified tea contaminants like aluminum, fluoride, mercury, lead, cadmium and arsenic (Fujimaki. 2004; Lung. 2008; Wang. 2008; Alvarez-Ayuso. 2011; Tan. 2012) in commercial tea preparations.
Table 1: There are not just bad, but also healthy minerals in tea!
Before we get to the "bad stuff", though, let's start with the positive findings of their investigation. The data in Table 1 is after all evidence enough that there are also "healthy" minerals in tea - the amount is not high enough to cover your RDA, but this does not mean that it could not be at least partly related to the undeniable health benefits researchers all around the world report for people who consume uncontaminated tea on a regular base. As a loyal SuppVersity readers you know most, if not all of them from previous articles on tea. The reason I still believe it's worth enumerating them again is that I don't want you to give up on your beloved (?) tea too easily - I mean, Coke is not an alternative and for coffee fungi and other stuff could make a similarly unhealthy "supplement" to your breakfast beverage:
  • Cardiovascular benefits - When we are talking about health in general and heart health in particular, most people will think of green tea. That's pretty unfortunate, because there is ample research for all varieties of teas that they can lower blood lipids, provide "clean" and thus heart healthy energy, and exert antithrombotic and anti-hypertensive effects.
  • Anticancer effects - Despite the fact that the anti-cancer effects have mostly observed in in-vitro studies, there is plenty of epidemiological evidence that tea drinkers have a lower cancer risk, than the average coke guzzler (not necessarily breast cancer, though ➫ SuppVersity Facebook News).
  • Metabolic syndrome - While more recent studies clearly suggest that the active weight loss effects of tea, in general, and green tea, in particular, have been totally overblown, there is still a host of controlled trials, where adding tea (not necessarily green tea) improved the effects of a energy restricted diet. Compared to the rodent trials which are still fueling the myth of the potent thermogenic effects of (green) tea, the real world results in human beings are however downright disappointing.
  • A green tea marinade will keep your meats fresh | learn more
    Anti-infective properties - Only few people (SuppVersity readers included - of course) know that green tea can be used as a mouthwash and is currently researched as an anti-bacterial food additive by researchers all around the world. According to a paper by Steinmann et al. (2013), the anti-infective effects are mediated by the antiviral, antibacterial, and antifungal properties of Epigallocatechin gallate (EGCG). The same EGCG about which you've read only recently on the SuppVersity that it is not exactly as useful as a fat loss adjuvant, as the hype would have you believe.
  • Other beneficial effects - Under "Miscellaneous Effects", Schwalfenberg et al. also list the nephropotective effects of green tea, which could come very handy if you guzzle mercury contaminated green tea, everyday (unfortunately, mercury is your least problem with tea), the anti-depressive researchers have observed in people consuming 4+ cups of tea per day and the hitherto unconfirmed hypothesis that tea drinkers are (better) protected against Alzheimer’s and neurological decline.
In view of these benefits it's only logical that the Canadian + Swedish research team chose to repeat  the dichotomous health effects of drinking tea in the title of their paper "The Benefits and Risks of Consuming Brewed Tea" (my emphasis in Schwalfenberg. 2013)

Organic is not better than regular tea

To obtain a dataset that would be as comprehensive, accurate and practically relevant as possible the authors bought 30 different organic and non-organic white, green, oolong, and black teas from the the shelves of Canadian supermarkets and analyzed (a) the "raw" tea leaves (LEAF), (b) tea that had been steeped for 3-4 minutes (3MIN), (c) tea that had been steeped for 15–17 minutes (15MIN).
Know your teas: As a SuppVersity reader you will probably know that all teas come from the same plant. It's the processing that determines if we call it "white", "green", or whatever else:
  • White tea: young leaves or new growth buds, withered, uncured, baked dry 
  • Green tea: steamed or dry cooking in hot pans to prevent oxidation; dried tea leaves may be separate leaves or rolled into pellets (gunpowder tea)
  • Oolong tea: withering of leaves under sun and warm winds with further oxidation standard between green and black teas
  • Black tea: leaves are completely oxidized, withered
Due to the processing of the leaves tea from the same camellia sinensis plant can contain different amounts of contaminants depending on whether you buy it as white, green, oolong or black tea, or shredded green tea supplement.
Still, the main determinant is and remains the soil it was grown on (see Table 4)?
All tea samples underwent the same standardized procedures before they were analyzed in their raw form (cut / shredded leaves) or as an infusion that had been prepared with only one tea bag (containing 2-3g of tea) in 250 mL of distilled water in fine bone china cups.

As you will already have expected, the scientists did not just detect the previously mentioned "good minerals" (exact values see Table 1), and a host of other beneficial trace elements, i.e.
  • boron 19–115µg/L, cobalt 0.4–3.56µg/L, 
  • copper 26–106µg/L, chromium 0.2–14.6µg/L, 
  • iron 19–62.5µg/L, manganese 534–6351µg/L, 
  • molybdenum 0.03–0.131µg/L, 
  • selenium <0.1–0.34µg/L, 
  • vanadium <0.01–0.151µg/L, and zinc 44.6–187µg/L,
in their samples. Schwalfenberg et al. found highly significant and, more importantly, physiologically relevant amounts of toxic elements, as well:
Table 2: Established toxicant limits in supplements (µg/day).
If you look at the value in Table 3 and compare them to the limits in Table 2, there is one thing you should keep in mind: These limits have been set by average exposure, not based on toxicity tests - that sounds very comforting, right?
"Public health warnings or industry regulation indicated" -- It sounds pretty fearmongering and I would not have used it as a subheading right beneath the introduction, if the statement "Public health warnings or industry regulation might be indicated to protect consumer safety." (Schwalfenberg. 2013) was no literal citation from the conclusion of the paper I have here right in front of me.
Table 3: Levels of mercury (Hg), lead (Pb), aluminum (Al), arsenic (As) and cadmium (Cd) in tea infusions after 3-4 or 15-17 min of brewing; all values in µg/L (Schwalfenberg. 2013)
A brief glimpse at the data in Table 3 does moreover confirm there are plenty of toxins in the average Canadian super market tea, but it does not tell you how problematic the contamination actually is. To understand that you'd have to cimpare those values to the established toxicant limits Table 2, which do - and this is and will always be ridiculous -  obviously depend on where you live *sarcastic laughter*... but enough of the unproductive sarcasm, let's see what we've got:
"All teas contained significant amounts of aluminum. Tea  leaves contained from 568 to 3287 ng/g of tea. All brewed teas steeped for 3 or 15 minutes contained detectable levels of aluminum. The range was 1131µgm/L to 8324µgm/L steeping for 3 minute and 1413µgm/L to 11449µgm/L steeping for 15 minutes. Only 2 teas had levels above acceptable limits at 3 minutes of brewing but 6 of the teas had levels greater than the upper acceptable daily limit of 7000µgm/L. Clearly letting tea steep for longer than 3 minutes is not advisable. Two of the organic green teas had levels above 10,000µgm/L brewed for 15 minutes."
In view of the fact that tea is by far not the only aluminum source you are expose to, the high levels of this toxic metal that easily accumulates in the body should be reason enough not to brew your tea - especially not organic tea - for more than 3 minutes.

Organic tea is a worse offender than regular

If you take a look at the amount of lead in the various tea samples it becomes even more obvious that "organic" tea is not necessarily better for your organs, as well. This is particularly true for the best-sellers green and black tea, both of which contain significantly more lead in the "organic" vs. "regular" variety.
Table 4: Toxicant levels according to origin; Pb: lead, Cd: cadmium, Al: aluminum, As: arsenic (Schwalfenberg. 2013)
Probably the main factor that influences the toxicant levels of teas is the place of origin, thoug. As you can see in the overview in Table 4, the highest amount of arsenic, was detected in Chinese oolong teas (organic or regular). The total arsenic levels in all teas, which ranged from 0.06µgm to 1.12µgm/L for tea that had been steeped for 3 minutes to 0.08 to 1.27µgm/L for tea that had been steeped for 15 minutes was highest in white tea - obviously also from China. And last but not least, ...
"...[a]ll tea leaves had detectable levels of cadmium. 21 teas had detectable levels after 15 minutes brewing while only 18  teas had detectable levels after 3 minutes brewing suggesting that there is further leaching of this toxicant into the water over time. [As the overview in Table 4 already suggests] the highest level was 0.067µgm/L found in standard oolong tea from China." (Schwalfenberg. 2013)
Not listed in the tables are the levels of tin, barium, antimony and thallium, which were detected in all tea samples, but at levels of which the authors state that they don't have to be "considered to be of concern" (Schwalfenberg. 2013).
Should you stop drinking tea? You know that I don't like to tell people what to do. Unless, obviously I am 100% sure that I am convinced that there is a serious health risk involved.
In the case of green, black or white tea, the evidence that this is the case is yet insufficient. Personally, I will still make sure to check the geographic origin of the tea leaves (not where it was processed and packaged!) and avoid all products with the bad 5-letter word C-H-I-N-A on the label.
Bottom line: "Not of concern" is not exactly what I would say about the overall results of the study at hand. I mean, in the end, the high levels of toxicants in some of the commercially available tea preparations - specifically those from China - could actually explain why the real-world results with commercially available teas and tea supplements often fall short of the rodent studies, which are often conducted with highly purified green tea products from companies like Sigma Aldrich.

Ah, ... one last thing to keep in mind is that 18 out of 30 tested commercial tea preparations contained mercury in amounts that were as high as 20 ng/g, but did not make it from the leave to the tea. With your digestive tract being a much more efficient nutrient and (unfortunately) toxicant extractor than hot water, tea supplements could pose an even greater risk of heavy metal exposure than tea.
References:
  • Álvarez-Ayuso, E., Giménez, A., & Ballesteros, J. C. (2011). Fluoride accumulation by plants grown in acid soils amended with flue gas desulphurisation gypsum. Journal of hazardous materials, 192(3), 1659-1666.
  • Hayacibara, M. F., Queiroz, C. S., Tabchoury, C. P. M., & Cury, J. A. (2004). Fluoride and aluminum in teas and tea-based beverages. Revista de Saúde Pública, 38(1), 100-105.
  • Lung, S. C. C., Cheng, H. W., & Fu, C. B. (2007). Potential exposure and risk of fluoride intakes from tea drinks produced in Taiwan. Journal of Exposure Science and Environmental Epidemiology, 18(2), 158-166.
  • Steinmann, J., Buer, J., Pietschmann, T., & Steinmann, E. (2013). Anti‐infective properties of epigallocatechin‐3‐gallate (EGCG), a component of green tea. British journal of pharmacology, 168(5), 1059-1073.
  • Tan, Z., & Xiao, G. (2012). Leaching characteristics of fly ash from Chinese medical waste incineration. Waste Management & Research, 30(3), 285-294.
  • Schwalfenberg, G., Genuis, S. J., & Rodushkin, I. (2013). The Benefits and Risks of Consuming Brewed Tea: Beware of Toxic Element Contamination. Journal of toxicology, 2013.
  • Wang, X. P., Ma, Y. J., & Xu, Y. C. (2008). [Studies on contents of arsenic, selenium, mercury and bismuth in tea samples collected from different regions by atomic fluorescence spectrometry]. Guang pu xue yu guang pu fen xi= Guang pu, 28(7), 1653-1657.