Safe Limit for Fluoride |
The National Pure Water Association says we are already ingesting more than the government’s safe limit. Do you agree?
BFS suggested answer
No. There is no evidence to support that claim. The so-called safe limit quoted by NPWA does not exist.
This claim is a misrepresentation of the term ‘safe intake’ as it is used in a Department of Health report. The report explains that ‘safe intakes’ are not intended as a ‘toxic level’. In fact it states that there is a wide safety margin above the more usual intakes in fluoridated areas. This has been pointed out to the NPWA on several occasions.
BFS suggested answer refuted
The most important and widely disregarded fact about dental fluorosis is that no safe established daily intake exists, i.e., the maximal amount in mg fluoride which, consumed daily, does not produce cosmetically damaging white areas or brown stain in some areas has not been fixed.
Dr Harold C. Hodge
The proponents of fluoridation have always insisted that fluoride has no adverse side effects: that it is quite harmless, that it does nothing other than strengthen teeth. Throughout this book you will see evidence which shows that much of that statement is suspect. The first suspicion that this is so comes in declarations by health authorities that fluoridated drinking water is perfectly safe1 – followed by recommendations for a safe or a maximum limit for daily intake.
The currently recommended level of 1 ppm (part per million) fluoride in drinking water aims to provide for a total intake of 1 mg per day. This assumes that an individual drinks 1 litre of water per day, despite the fact that health experts recommend an intake of three times that amount and even more in hot weather.
The bodge by Hodge
It is important when any new drug is marketed that the exposure at which it is toxic is determined. Then a margin is allowed for safety (usually a factor of 100) and a maximum exposure published.
In 1953 the National Academy of Sciences published their estimate of the quantity of fluoride which produces the condition known as crippling skeletal fluorosis. The calculation was done by a famous toxicologist, Harold C. Hodge, PhD, who at that time was chairman of the US National Academy of Sciences (NAS) committee on toxicology.
To arrive at his figures, Hodge cited the classic study of the effects of fluoride among cryolite workers published in 1937 by European researcher, Kaj Roholm.2 Roholm’s dosage figures, presented in milligrams of fluoride per kilogram of body weight, showed that at levels of 0.2–0.35 mg/kg, the first stage of the disease appeared, in general, after two and a half years; stage 2 was reached by four and a half years; and crippling skeletal fluorosis appeared after eleven years.
Hodge wanted to apply Roholm’s figures to a typical range of body weights in order to set a maximum intake level in milligrams per day. But Hodge, an American, was used to dealing in pounds rather than kilograms. Using body weights from 100 to 229 pounds, he multiplied the 0.2 mg figure by 100 pounds, giving a figure of 20 mg/day; and 0.35 mg by 229 pounds to give 80 mg/day. Thus, the amounts of fluoride that would cause crippling skeletal fluorosis, he said, were 20–80 mg/day for a period of ten to twenty years. These are the figures that appear in the American Dental Association’s pamphlet, Fluoridation Facts, and on which many other articles are based, even today.
But Hodge had made a simple but significant error: in converting fluoride amounts from milligrams per kilogram to milligrams per pound, he got it wrong. Unfortunately, Hodge was the expert, and no-one, apparently, queried or even checked his figures. This error, which gave a false safety margin more than double what it should have been, went unnoticed for many years until an American anti-fluoride campaigner, Darlene Sherrell, tried to duplicate Hodge’s arithmetic and couldn’t make the figures add up.
Correcting for the error, Sherrell reduced the amount of fluoride needed to be crippling to 10–25 mg/day, over a period of ten to twenty years. Duration of exposure is important, because fluorides accumulate in our bodies throughout our lives, so a higher intake over a shorter period of time will have the same effect as smaller doses over a longer period of time. If we apply Roholm’s dosage figures to a lifetime of 55–96 years, just 1 mg per day (the amount in 1 litre of water) for each 55 pounds of body weight could be a crippling dosage.
The NAS admits it was wrong
In 1979 Hodge corrected his previous figures in a book, Continuing Evaluation of the Use of Fluorides, but nobody seems to have noticed. Sherrell wrote to the National Academy of Sciences in 1989. In 1991, when scientists at the US Department of Health and Human Services published their Review of Fluoride: Benefits and Risks, they continued to use figures of 20–80 mg/day as the ‘crippling daily dose of fluoride’. The error was finally corrected by the National Research Council’s Board on Environmental Studies and Toxicology in 1993, when they changed the figure from 20–80 mg/day to 10–20 mg/day.3 Even today, the current recommended daily allowance (RDA) and dietary reference intakes, published by the US Institute of Medicine, still use the wrong figures.
Myths are very hard to dislodge.
‘Optimum’ levels and safe limits
When 1 ppm fluoride was first recommended, water was about the only source of fluoride in diet. Today that is no longer the case. Studies indicate that total fluoride ingestion today approaches 4.0 mg per day even in areas without water fluoridation. Commercial beverages may be manufactured with fluoridated water; it is present in foods; toothpastes and oral hygiene products contain substantial amounts of fluoride, as do some medications. Thus, even in unfluoridated areas, many now receive substantially more fluoride than the ‘ideal’ amount.
In 1996, for the first time, the UK Department of Health published safe fluoride intakes at various ages: in adults, the Department of Health suggests that this is 3 mg per day.4 This differs from the American standard, and this flat rate also takes no account of differences in age, size, ambient temperature – we drink more when we are hot – or any other factor. The USA’s Nutrition Board of the Institute of Medicine attempted to address this problem, basing intakes on age and body weight (see Table 1).
But no matter what scales are used, just how meaningful are safe intakes? People drink different amounts of water each day. At an ‘optimal’ concentration of 1 ppm, the British 3 mg/day is the amount found in just 3 litres, or 5 pints, of water. Tea, grown in areas with high concentrations of fluorine in the soil, is itself a significant source of fluoride in Britain and Ireland.
 |
||||
Age group |
Reference |
weights |
Adequate |
Tolerable upper |
|
kg |
(lb)a |
|
|
|
||||
Infants 0–6 months |
7 |
(16) |
0.01 |
0.7 |
Infants 6–12 months |
9 |
(20) |
0.5 |
0.9 |
Children 1–3 years |
13 |
(29) |
0.7 |
1.3 |
Children 4–8 years |
22 |
(48) |
1.0 |
2.0 |
Children 9–13 years |
40 |
(88) |
2.0 |
10 |
Boys 14–18 years |
64 |
(142) |
3.0 |
10 |
Girls 14–18 years |
57 |
(125) |
3.0 |
10 |
Females 19+ years |
76 |
(166) |
4.0 |
10 |
Males 19+ years |
61 |
(133) |
3.0 |
10 |
|
||||
aValues based on data collected between 1988 and 1994 as part of the Third Health and Nutrition Examination Survey (NHANES III) in the United States.
Table 1. Dietary reference intakes for fluoride
In 1953 it was reckoned that ‘exclusive of drinking water, the average diet in the United States is calculated to provide 0.2 to 0.3 milligrams of fluoride daily. Drinking water . . . can provide an optimal internal supplement of approximately one-half to 1 milligram of fluoride per day.’5 In 1974, average intake was from about 1.7 to 3.44 mg/day. Three years later, the dangers of such a high level of intake were revealed by the National Academy of Sciences:
Recent studies indicate that the total intake of fluoride is as high as 3 mg/day rather than the earlier figure of 1.5 mg/day, primarily because of increases in the estimated levels of fluoride in food. Balance data presented by Spencer also suggest a higher retention by bone, nearly 2 mg/day, rather than the 0.2 mg/day indicated earlier . . . These findings are important . . . a retention of 2 mg/day would mean that an average individual would experience skeletal fluorosis after 40 yrs.6
Despite such warnings, by 1991, the average fluoride intake in fluoridated American cities had more than doubled to over 6.5 mg daily.7 Current intake is now approaching 8 mg per day, not just from tap water, but from toothpaste and other dental products, beverages, processed foods, fresh fruits and vegetables, pharmaceuticals, Teflon- and Tefal-coated cookware, vitamins and mineral supplements, tea, air . . . the list is endless. This relentless increase in fluorides in our diet means that ‘[i]t is no longer feasible to estimate with reasonable accuracy the level of fluoride exposure simply on the basis of concentration in drinking water supply’.8
It’s worse for children
Scientists at the Dental Research Unit, Wellington School of Medicine, New Zealand, analysed 532 juices and juice drinks for fluoride and found concentrations that ranged as high as 2.80 ppm, in part because of the fluoride in water used in production. They say that children’s ingestion of fluoride from juices and juice-flavoured drinks can be a substantial factor in the development of fluorosis.9 A study of 332 fizzy drinks had similar findings in 1999.10
Sales of bottled drinking waters in the United Kingdom tripled between 1989 and 1994. Analysis of the fluoride content of twelve bottled waters purchased in 1994 from two Leeds supermarkets showed that they contained from 0.10 to 0.80 ppm fluoride.11 Although the bottles’ labels listed fluoride concentrations, most were inaccurate. The authors of this study warn that some parents using bottled waters to prepare baby milk formulations that themselves may contain high levels of fluoride may subject their children to the risk of dental fluorosis. Dr S. Levy and colleagues of Iowa City confirmed this the following year. They found that water fluoride intake in infants up to nine months old from reconstituted concentrated infant formula ranged as high as 1.57 mg per day.12 This is up to 157 times the adequate intake and more than double the tolerable upper intake for infants of this age, as defined by the US Third National Health and Nutrition Examination Survey, NHANES III.
The pesticide cryolite, which is 54.3 per cent fluorine, is found on apples, raisins, lettuce, tomatoes, potatoes, peaches, and most berries.13 The American Consumers Union stated that just one serving of some popular fruits and vegetables could contain enough harmful chemicals to exceed US government health standards – not surprising when almost half of forty-three ready-to-drink fruit juices contained more than 1.0 ppm fluoride, with grape juice containing up to 6.8 ppm.14 The ACU concluded that children were most at risk – in part because their bodies are more sensitive, but also because they typically consume more fresh fruit for their weight than adults.15
The Journal of the Canadian Dental Association states: ‘Fluoride supplements should not be recommended for children less than 3 years old.’16 Also: ‘The ADA recommends the use of fluoride mouth rinses, but not for children under six years of age because they may swallow the rinse.’17 If fluoride really is safe, why does swallowing it matter?
In 1995 the Journal of the American Dental Association (JADA) proclaimed:
Some children had estimated fluoride intake from water, supplements and dentifrice that exceeded the recommended ‘optimal’ intake (a level that has yet to be determined scientifically). Practitioners should estimate fluoride ingestion from all of these sources if considering systematic fluoride supplementation.18 [emphasis added]
But wait – a level that has yet to be determined scientifically? What kind of people will recommend giving a medication to the whole population, while admitting that after more than fifty years of so doing, they still haven’t determined what the ‘optimal’ level is?
And that question prompts still more questions:
•If we haven’t determined what the ‘optimal’ level is, how meaningful is it to publish one?
•More importantly, what evidence is there that this level is both effective and safe?
•And how are different people, with different lifestyles, to be protected from ingesting too much? Different people consume different amounts of fluoridated water. For example, athletes, labourers, diabetics and residents of hot or dry regions may drink more water, and therefore more fluoride, than do other people.19 As a result, it is impossible accurately to control the dosage of fluoride any person ingests.
A safe level should be defined
Before addition to foods, all chemical additives have to be tested for toxicity. After determination of the amount found to be toxic ‘to the average person’, this amount is divided again to ensure that the amount ‘will be safe for almost everybody’. For some unaccountable reason, this is not the case with fluoride. The level of fluoride that is deemed ‘optimal’ is separated by only a small amount from the amounts that are known to be harmful. Dr James Patrick, a former antibiotics research scientist at the US National Institutes of Health, described this fine distinction:
[There is] a very low margin of safety involved in fluoridating water. A concentration of about 1 ppm is recommended . . . in several countries, severe fluorosis has been documented from water supplies containing only 2 or 3 ppm. In the development of drugs . . . we generally insist on a therapeutic index [margin of safety] of the order of 100; a therapeutic index of 2 or 3 is totally unacceptable, yet that is what has been proposed for public water supplies.20
In other words, if the rules for other chemicals were applied to a chemical as ubiquitous as calcium fluoride, the only safe level in an essential public resource such as drinking water would be no more than 0.01 ppm. Given this parameter, should we not now be pursuing a very strict policy of removing as much calcium fluoride as possible from what we eat and drink? There should certainly be no suggestion of adding any.
Conclusion
The answer that the BFS suggests is strictly correct. But it is a cleverly worded question and answer. There is no such thing as a British government safe limit for the simple reason that no government body has ever bothered to determine just how much fluoride is safe. There is, however, a British safe intake: it is 3 mg per day for an adult. You may wonder what is the significance of publishing a safe intake, if it is not related to an unsafe intake?
We know from Roholm’s figures that an intake of 3 mg per day has the potential to cause crippling skeletal fluorosis well within a normal lifetime. Thus, there is certainly not ‘a wide safety margin above the more usual intakes in fluoridated areas’.
It is impossible for members of the public to determine how much fluoride they are ingesting. Even if you avoid commercially packaged foods and drinks, as I do, there is a plentiful supply of fluoride in fresh foods, as food animals may drink fluoridated water, while crops are sprayed with fluoride-based (cryolite) pesticides and, when picked, may be washed or packed in fluoridated water.
Incidentally, the city of Natick, Massachusetts, USA, was forced to fluoridate its water supplies by the public health service in 1998. Natick selectmen, the town’s top elected officials, are responsible for warning residents any time they are in danger. Following fluoridation, water bills sent to all users carried the following warning printed in bold letters:
This water contains fluoride per order of the Natick Board of Health.
We recommend that pregnant women, parents of children under 3 years of age, and individuals with known fluoride sensitivity consult with their personal physicians before drinking this water.21
That’s how safe they think fluoridated drinking water is!
1.Scarrott D. British Dental Association. Personal correspondence to author. 5 June 1997.
2.Roholm K. Fluorine intoxication. A clinical–hygienic study. Copenhagen: Nyt Nordisk, and London: HK Lewis, 1937: 281–2.
3.Health effects of ingested fluoride. US National Academy of Sciences, 1993: 59.
4.UK Department of Health. Report on health and social subjects. 41: Dietary reference values for food energy and nutrients for the United Kingdom. 8th impression. London: HMSO, 1996: 189.
5.The problem of providing optimum fluoride intake for prevention of dental caries. Food and Nutrition Board, Division of Biology and Agriculture, National Academy of Sciences, US National Research Council, Publication No. 294, November 1953.
6.Drinking water and health. Safe Drinking Water Committee, National Academy of Sciences, US National Research Council, 1977: 372.
7.Review of fluoride: Benefits and risks. US Department of Health and Human Services, February 1991: 17.
8.Health effects of ingested fluoride. Subcommittee on Health Effects of Ingested Fluoride, Committee on Toxicology, Board on Environmental Studies and Toxicology, Commission on Life Sciences, US National Research Council, August 1993: 128.
9.Kiritsy MC, Levy SM, Warren JJ et al. Assessing fluoride concentrations of juices and juice-flavored drinks. J Am Dent Assoc 1996; 127: 895–902.
10.Heilman JR, Kiritsy MC, Levy SM, Wefel JS. Assessing fluoride levels of carbonated soft drinks. J Am Dent Assoc 1999; 130: 1593–9.
11.Toumba KJ, Levy S, Curzon ME. The fluoride content of bottled drinking waters. Br Dent J 1994; 176: 266–8.
12.Levy SM, Kohout FJ, Guha-Chowdhury N et al. Infants’ fluoride intake from drinking water alone, and from water added to formula, beverages, and food. J Dent Res 1995: 74: 1399–1407.
13.Yiamouyiannis J. Fluoride – The aging factor. 3rd edn. Delaware, OH: Health Action Press, 1993.
14.Stannard JG, Shim YS, Kritsineli M, Labropoulou P, Tsamtsouris A. Fluoride levels and fluoride contamination of fruit juices. J Clin Pediatr Dent 1991; 16: 38–40.
15.Washington Post, 17 Feb 1999. http://www.washingtonpost.com/wpsrv/national/pesticides.htm.
16.Canadian Conference on the evaluation of current recommendations concerning fluorides, April 9–11, 1992, Fluoride recommendations released. J Can Dent Assoc 1993; 59: 330.
17.http://www.ada.org/public/topics/fluoride/artcl-01.html.
18.SM Levy, Kohout FJ, Kiritsy MC, Heilman JR, Wefel JS. Infants’ fluoride ingestion from water, supplements and dentifrice. J Am Dent Assoc 1995; 126: 1625.
19.Exner FB, Waldbott GL. The American fluoridation experiment. New York: Devin-Adair, 1957: 43.
20.Statement by Dr James Patrick before Congressional subcommittee, 4 August 1982. Cited in Null G, Feldman M. The case against fluoridation. http://www.garynull.com/documents/fluoride1.htm
21.Middlesex News, Natick, MA, Tuesday, 10 March 1998.