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In: "Cheap tea bags contain frighteningly high fluoride levels: Study"

on 'Natural News', it says:

A new study published in the journal, Food Research International, has revealed that millions of people across the globe are at serious risk of developing tooth decay, bone loss, and other serious health conditions as a result of over-exposure to fluoride. Many inexpensive, store brand black and green teas, it turns out, contain dangerously high levels of fluoride that far exceed even the government's over-inflated maximums for fluoride exposure.

Though it focused mainly on private label tea brands sold in the U.K., the study identified what is presumably a reality in many developed nations — cheap teas generally contain levels of fluoride so high that drinking them may be considered unsafe.

  1. Are the findings in the study accurately reflected in the article?

  2. Are the findings in the study corroborated by other studies, or contradicted?

  3. Is the study's methodology sound?

  • 3
    That page links to nhs.uk/news/2013/07July/Pages/…, and that page references the original research abstract sciencedirect.com/science/article/pii/S0963996913000446. Searching the title finds e.g. researchgate.net/publication/… where the full article can be downloaded. That means you can do your homework regarding question 1. – user22865 Oct 14 '16 at 20:05
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    "... on Natural News ..." and that's when I stopped reading. Notorious for making claims unsupported or even directly contradicted by the evidence cited - assuming the evidence is real at all. – Nij Oct 17 '16 at 3:53
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    @Nij: That is an ad hominem fallacy. Natural News raises my skeptical hackles, but that isn't enough reason to dismiss the claim outright. – Oddthinking Nov 26 at 9:33
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    If you can cite an article on Natural News that does not distort facts or misquote others in order to make its point, there might be a point. Even Fox News provides factual reporting (and despite editorial slanting, it can be fairly accurate). But not once have I ever seen Natural News provide sufficient evidence to base their claims on. It's not ad hominem to recognize the utility of reading a source once identified and decide whether to continue reading based on that knowledge. In this case, the utility is zero, and continuing would have been a complete waste. – Nij Nov 26 at 10:01
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Q. 1: Are the findings in the study accurately reflected in the article?

In the study, as described on Food Research International: Human exposure assessment of fluoride from tea (Camellia sinensis L.): A UK based issue?, they measured the amounts of fluoride in various teas and then only commented (not investigated) their possible side effects as described in other studies; for example, they said that some cheap teas on the UK market have fluoride contents comparable to "brick tea," which was associated with many cases of dental and skeletal fluorosis in China. The article also mentioned a possible association between cheap teas and cancer.

The article on Natural News: Cheap tea bags contain frighteningly high fluoride levels: Study made an abstract of the study article and actually presented the possible side effects of tea in less dramatic way than the original article.

Q. 2 and 3: Are the findings in the study corroborated by other studies, or contradicted? Is the study's methodology sound?

One author in Nutrition Bulletin, 2014 questioned the method used to measure fluoride in tea in said study, but he did not prove it wrong. The researchers from Medical College of Georgia/US have found similar levels of fluoride in some black teas (Science Daily, 2010), so, the data in the UK study seems plausible.

The summary of evidence from studies:

  • In the mentioned UK (and other studies), they have found up to 9 mg fluoride per liter of some cheap teas.
  • Adverse effects of excessive fluoride intake can include:
    • Dental fluorosis due to fluoride intake as low as 1 mg/day before age 8
    • Skeletal fluorosis after fluoride intake >10 mg/day for at least 10 years
    • In the US and UK, there have been only sporadic cases of severe dental or skeletal fluorosis documented and most of them have been associated with the consumption of >20 mg fluoride, usually due to drinking " a gallon" or more tea daily for more than 2 decades.
    • In China, drinking about 2 liters of tea with total daily consumption ~12 mg fluoride/day for decades (but in children only for few years) has been associated with many cases of dental and skeletal fluorosis.

The amount of fluoride in tea

According to the study in the UK, 2013:

Fluoride concentrations in UK tea, including the leading supermarket economy labelled products, were determined. Fluoride ranged from 93 to 820 mg/kg in the products and 0.43 to 8.85 mg/L in the infusions.

Amount of fluoride (in mg/liter) in various types of tea after brewing for 2 minutes in deionized (non-fluoridated) water (Table 3):

  • Economy blends (Tesco Value bags 1): 3.60-7.96
  • Black blends (PG Tips bags): 0.76- 4.98 mg
  • Green blends (Clipper Organic leaf): 1.62-4.32
  • Pure blends (Asam leaf): 0.71-2.5 mg
  • Oolong (Luk Yu Oolong): 0.43-1.43 mg

The fluoride content is highest in cheap teas, because they contain more mature tea leaves. Other black and green teas can also contain a lot of fluoride, but herbal teas usually only little.

Data about fluoride in teas from other studies (fluoride/liter tea):

Safe fluoride intake levels

According to The National Academies, 1997, in the US, the Tolerable Upper Intake Level (UL) for fluoride (the amount that should not cause any side effects except mild dental fluorosis) is:

  • 0-6 months: 0.7 mg/day
  • 7-12 months: 0.9 mg/day
  • 1-3 y: 1.3 mg/day
  • 4-8 y: 2.2 mg/day
  • 9 y and older: 10 mg/day

Dental fluorosis

1) Dental fluorosis refers to yellow discoloration of the permanent teeth due to excessive fluoride intake until age 8, but not later (The National Academies, 1997):

The preeruptive maturation of the crowns of the anterior permanent teeth is finished and the risk of fluorosis is over by 8 years of age (Fejerskov et al., 1977). Therefore, fluoride intake up to the age of 8 years is of most interest. Several reports suggest that enamel in the transitional or early maturation stage of development is most susceptible to fluorosis, which for the anterior teeth, occurs during the second and third years of life.

and:

...milder forms of enamel fluorosis affected the permanent teeth of 10 to 12 percent of permanent residents in communities where the drinking water had a fluoride concentration close to 1.0 mg/liter. The fluoride intake of children with developing teeth in these communities averaged 0.05 mg/kg/day and ranged from 0.02 to 0.10 mg/kg/day...Mild enamel fluorosis affected about 50 percent of residents where the water contained 2.0 mg/liter of fluoride. At this concentration, a few cases (< 5 percent) of moderate fluorosis were recorded (Dean, 1942). Fluoride intake by most children in these communities would have ranged from approximately 0.08 to 0.12 mg/kg/day. An average, chronic daily fluoride intake of 0.10 mg/kg appears to be the threshold beyond which moderate enamel fluorosis appears in some children. Where the water fluoride concentration was 4.0 mg/liter, nearly 90 percent of the residents had enamel fluorosis, and about one-half of the cases were classified as moderate or severe.

2) Teeth with mild fluorosis appear to be more resistant to caries:

Fluoride and Dental Caries Prevention in Children (California Dental Association, 2014):

Almost all fluorosis in the United States is very mild or mild (Figure 4); (44) teeth with this degree of fluorosis are more resistant to caries than teeth without fluorosis. More severe dental fluorosis, which manifests as enamel pitting and predisposition to staining (Figure 3D), is unusual in the United States but occurs in other parts of the world where there are naturally high levels of fluoride in the water (eg, >2 ppm). Teeth with severe fluorosis are paradoxically more susceptible to caries.

3) In one small 1996 study in Tibet, more than 50% of children who have consumed about 5.5 mg fluoride/day, mainly by brick tea, had dental fluorosis.

Skeletal fluorosis

Skeletal fluorosis refers to skeletal pain and deformities due to increased bone mass caused by high fluoride intake. According to The National Academies, 1997:

an intake of at least 10 mg/day for 10 or more years is needed to produce clinical signs of the milder forms of the condition.

1) The article Skeletal fluorosis and instant tea (The American Journal of Medicine, 2005) describes a case of a 52-years-old woman who developed skeletal fluorosis after drinking 1-2 gallons (4-8 liters) of instant tea prepared with fluoridated water for about 30 years (estimated fluoride intake: 37 to 74 mg/day).

2) In another article: Skeletal Fluorosis From Instant Tea (The Journal of Bone and Mineral Research, 2009), a 49-year-old woman, who was drinking 2 gallons (~8 liters) of instant tea with 5.8 mg fluoride/liter from age 12 (estimated fluoride intake: 44 mg/day.) has developed skeletal fluorosis.

3) In a study in Tibet/China: Brick tea fluoride as a main source of adult fluorosis, Food and Chemical Toxicology, 2003, most adults who were habitually drinking "brick tea" (average fluoride intake: 12 mg/day) had some osteosclerosis or arthritis.

4) In another study in Tibet Prevalence of Brick Tea-Type Fluorosis in the Tibet Autonomous Region (Journal of Epidemiology, 2016), 18-84 % of adults who were regularly drinking brick tea had skeletal fluorosis.

Hypothyroidism

In the studies in Saudi Arabia, 2010, the UK, 2012/13, Ireland, 2016, Canada, 2018, India, 2018 and Iran, 2018 they have observed an association between modest fluoride intake by tea and fluoridated water and hypothyroidism, especially in the individuals with iodine deficiency, but more research is warranted.

Cancer

I have found no studies about fluoride in tea and cancer, but according to Agency of Toxic Substances and Disease Registry, 2013, there is no association between high fluoride intake from water and cancer:

Most of the studies of people living in areas with fluoridated water or naturally high levels of fluoride in drinking water did not find an association between fluoride and cancer risk.

In conclusion:

  • Dental fluorosis (yellow discoloration of permanent teeth) can develop in children under age 8 who regularly drink tea with as little as 1 mg fluoride/liter. Mild fluorosis decreases, but severe fluorosis (>2 mg fluoride/day) increases the risk of caries.
  • Skeletal fluorosis (increased bone density with skeletal pain or deformities) can develop in adults who start to drink tea as children or adults and consume at least 10 mg fluoride/day (for example 2 liters of tea with 5 mg fluoride/liter) for at least 10 years. Drinking 1 liter of tea with the highest fluoride level in the UK study (8 mg/liter) should not have any side effects in adults. Skeletal fluorosis in the US and UK is extremely rare.
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Yes, fluoride is dangerous, if consumed in excess, of any source.

But also no: real tea (that is made from Camellia sinensis plant, which has relatively high levels of fluoride) consumed in usual amounts (compared as 'usual consumer behaviour' like in high-amount tea drinking populations like Frisia, Ireland, Turkey, China, Japan or the UK) are unlikely to fall into that range. Cheap tea bags are higher in fluoride, but not even those approach real 'danger' levels.

As usual, dose makes the poison. And fluoride is beneficial in small amounts. After the age of 10, it seems that US people should strive to get an intake of daily fluoride between 3–10mg. That may be difficult to achieve if water or foods aren't fluoridated and no tea is consumed…

Other fluoride sources than tea should be considered though: high fluoride water, whether occurring 'naturally' or per artificial fluoridation, other foods and especially excessive oral hygiene products usage might combine to levels of concerns where limiting tea consumption should be considered.

Water fluoride content above 0.7mg/l is when supplements get problematic and thus tea consumption may get an issue.

Thus the keywords are really cheap tea (just as a rule of thumb for 'high in fluoride'), and copious amounts, and long-term consumption, and total fluoride intake from other sources.

A 2011 study in the Journal of Clinical Endocrinology and Metabolism concluded that skeletal fluorosis “can result from chronic consumption of large volumes of brewed tea” and that “daily consumption of 1-2 gallons of instant tea can lead to skeletal fluorosis.”
–– Cathy Hester Seckman: "Hidden fluoride in tea and other foods and beverages", RDH, May 1, 2019.

This exact alarmist piece of journalism presented by the claim on 'Natural News' was covered by the NHS in the UK:

The study is of interest, but it does not show that people using economy teas are putting their health at risk from consuming too much fluoride.

The study was carried out by researchers from the University of Derby and the former Health Protection Agency (now part of Public Health England). The study was published in the peer-reviewed journal Food Research International.

It was covered widely and uncritically in the media. Headlines claiming that cheap tea bags may make you ill are alarmist and not supported by this study.

This study suggests that people drinking economy brands of tea may be exposed to high levels of fluoride, which can cause dental and bone problems. The researchers calculate that people drinking 1 litre of cheap tea a day may be consuming more fluoride than the daily recommended amount, as advised by US experts. However, as the authors themselves say, in the US the “upper tolerable limit” of fluoride is 10mg of fluoride daily. The researchers’ calculations are not based on this maximum limit – but on recommended daily intake.

In some parts of the world the natural fluoride levels in water are excessive and this is known to cause serious dental and bone problems.

In the UK, severe fluorosis is rare, although mild fluorosis, in which the teeth become stained, may occur in children given fluoride supplements.

If your budget can only stretch to economy teabags then there is no real cause to worry as long as you limit your tea consumption.

While there is no official guidance, most experts recommend drinking no more than three mugs of tea a day on a regular basis.
–– Bazian: "Do fluoride levels in cheap tea pose a health risk?" Behind the Headlines – Food and diet, NHS UK, Thursday 25 July 2013.

And this is backed up by a less alarmist study:

  • F was higher in traditional tea (296–1112 mg/kg) and infusion (1.47–6.9 mg/L).
  • F was lower in herbal tea (33–102 mg/kg) and infusion (0.06–0.69 mg/L).
  • High soluble F in infusion was observed for all teas up to 96–99% of F.
  • F in teas poses no health hazard for both adults and children (HQ < 1).
  • Some tea samples might contribute >4 mg F/d, adding to F burden.

the health risk of F associated with the consumption of 47 traditional and herbal teas. The level of F was the least in herbal teas (33–102 mg/kg) and their infusion (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 total F in herbal and traditional teas were released into solution. The CDI values exceeded the stipulated value of 0.05 mg/d/kg bw in 10 teas, including 5 green teas, but none of the herbal teas exceeded the CDI value. Considering the HQ, drinking teas posed no imminent health hazards to both adults and children. However, since we did not consider F from food and drink sources, health risks from tea consumption cannot be ruled out. Hence, it can be predicted that long-term consumption of copious quantities of traditional tea might increase the chances of fluorosis in the consumers.
–– Suchismita Das et al.: "Fluoride concentrations in traditional and herbal teas: Health risk assessment", Environmental Pollution, (2017).

The country with highest per capita black tea consumption would be Frisia but Ireland in second place by volume consumes more 'cheap' tea. Plus water in Ireland is fluoridated.

The public health perspective there:

the high fluoride levels measured in black tea prepared from packaged black tea bag products sold in the RoI are consistent with concentrations found in similar products sold in Taiwan; China; Poland; Slovenia; UK; Germany; Norway and the USA.

A number of conclusions can be drawn from this study. First, the main finding of this study is that tea is the major source of exposure to fluoride in the general population. Second, for both adults and children the total dietary intake of fluoride from tea can exceed the upper tolerable intake limit (UL) at levels known to cause chronic fluoride intoxication. Third, while there have been no diagnosed cases of skeletal fluorosis in the RoI we provide evidence to suggest that excessive fluoride may be contributing to the high prevalence of musculoskeletal disorders, undiagnosed clinical stage 1 and stage 2 skeletal fluorosis. This suggests that the lack of any confirmed cases of clinical or sub-clinical fluorosis in the RoI may only reflect a lack of biomonitoring or a lack of awareness of the public health impact of the disease. Fourth, due to the high prevalence of iodine, calcium and vitamin D deficiency, malnutrition and diabetes, we provide evidence to suggest that the high fluoride intake of the population may also be contributing to other disease states. Last, our data suggests the tea products available in the RoI do not comply with EU food law. Taken together, our data and evidence from published literature unequivocally demonstrates that in countries where tea drinking is common fluoridation of public water supplies is unnecessary and potentially harmful. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population.
–– Declan T. Waugh et al.: "Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation", Int J Environ Res Public Health. 2016 Mar; 13(3): 259. Published online 2016 Feb 26. doi: 10.3390/ijerph13030259

Since Frisia has an average per capita consumption of 300 liters of black tea, any dangerous consequences from 'too high fluoride in black tea' should be manifest there. Just the saying that caries in Frisia would be 20% lower than the national average. I found not a single mention of this problem of too high fluoride for that region linked to tea consumption.

A different take to interpret the original claim is thus:

Tests on 49 tea bags found drinking about four cups a day gave people the daily recommended intake of fluoride…
–– Kate Pickles: "Why Budget Tea Bags Are Better For Your Teeth: Tests Reveal Cheaper Brands Contain The Most Tooth-Strengthening Fluoride", Fluoride Action Network, November 26th, 2015.

Or as the Tea Advisory Panel likes to interpret things:

  • Current intakes of tea are unlikely to provide fluoride intakes that exceed safe limits for adults and children
  • However, current intakes of tea do not provide enough fluoride to meet the RDA
  • Therefore, potential dental health benefits of fluoride cannot be accessed unless tea consumption increases to 3-4 servings/d from present intake of 1-2 servings/d.

–– CHS Ruxton: "Fluoride content of UK retail tea: comparisons between tea bags and infusions", Tea Advisory Panel, 2014. (PDF)

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