From Volume 38, Issue 2, March 2011 | Pages 86-92
The effects of fluoride are regularly discussed in newspapers. This paper reviews this coverage over a ten-year period and compares the content with contemporary scientific evidence. The reporting used in a sample of daily newspapers when the subject of fluoride and its effects were mentioned was analysed and factual statements within the articles were compared with contemporary scientific studies, to assess the accuracy of reporting.
There is extensive evidence that indicates that fluoride reduces caries in children and adolescents.1 A relatively recent study has also shown that caries rates can be reduced by as much as 25% in adults over the age of 40.2
In the United States, the Centers for Disease Control and Prevention have stated that fluoridation was:
One of the ten greatest public health achievements of the 20th century.3
National newspapers have a typical daily circulation of over nine and half a million copies,4 and provide news and information to large numbers of the general public. The views of those for and against fluoridation are widely contrasting, and are regularly expressed in newspapers.
Using the Nexis™ news database provided by the University of Birmingham Library, 13 daily newspapers were searched for any mention of the word fluoride. The search was done retrospectively from 1st January 1999 to March 2009. The search revealed 1483 articles that had the word fluoride in the text.
The newspapers were:
Tabloids
Broadsheets
Articles were excluded where fluoride was mentioned solely as an ingredient, where elemental fluoride was the focus (eg mining), in humorous articles, or where the article was promotional. Some articles were not included as they were duplications or later reprints of the same article.
Analysis of each article sought to establish whether the narrative exhibited any positive or negative statements about the presumed effects of fluoride, in order to gauge the overall article slant. For each article, one mark was scored for any positive statement such as:
….and will argue that (fluoride) is an effective and relatively easy way to help poorer children by preventing dental problems in later life. Because of fluoride's undoubted contribution to reducing tooth decay,… Tooth decay is caused by sugar in the diet. It is prevented by the appropriate use of a fluoride toothpaste, improving the diet, and where appropriate, fluoridating the water. Fluoride strengthens the enamel of teeth,…
Any mention of the negative effects of fluoride was recorded for each article, such as:
Fluoride in tap water can cause bone cancer in boys, a disturbing new study indicates, …opponents claim it (fluoride) poses potential risks, including lower IQ in children and bone cancer. Fluoride in water doesn't work because it is in quantities too small to protect teeth yet large enough to be dangerous. Studies have shown it has been linked to cancer,…
A score of no slant was given where the article gave equal credence. A list of reported side-effects was made.
Table 1 gives a breakdown of the articles included in the study by year of publication and by newspaper. A total of 717 (48%) of the 1483 articles identified were included in the study. The eight tabloid newspapers were responsible for 440 (61.4%) of the articles. The broadsheets contributed 277 (38.6%). The Daily Mail printed 170 (23.7%), the highest number of articles.
| Newspaper | 2009 | 2008 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 | 1999 | TOTAL |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daily Mail | 3 | 21 | 15 | 18 | 17 | 9 | 17 | 17 | 19 | 16 | 18 | 170 |
| Daily Mirror/Sunday | 0 | 14 | 6 | 11 | 8 | 10 | 13 | 11 | 12 | 10 | 10 | 105 |
| The Times/Sunday | 1 | 13 | 11 | 8 | 4 | 9 | 22 | 9 | 7 | 5 | 7 | 96 |
| The Independent | 0 | 5 | 1 | 0 | 4 | 5 | 12 | 6 | 6 | 8 | 13 | 60 |
| Daily Star | 0 | 2 | 4 | 1 | 3 | 11 | 18 | 11 | 2 | 3 | 0 | 55 |
| The Sun/News of World | 0 | 8 | 7 | 3 | 1 | 7 | 10 | 2 | 6 | 7 | 2 | 53 |
| The Telegraph/Sunday | 3 | 11 | 1 | 1 | 8 | 13 | 9 | 1 | 1 | 0 | 0 | 48 |
| The Guardian | 2 | 2 | 2 | 2 | 7 | 4 | 7 | 3 | 1 | 4 | 9 | 43 |
| Daily Express/Sunday | 0 | 10 | 10 | 2 | 2 | 4 | 3 | 0 | 2 | 3 | 0 | 36 |
| The Observer | 2 | 2 | 3 | 1 | 2 | 6 | 7 | 3 | 0 | 1 | 3 | 30 |
| The Morning Star | 0 | 0 | 0 | 0 | 0 | 0 | 6 | 4 | 1 | 0 | 0 | 11 |
| The People | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 2 | 1 | 1 | 3 | 10 |
| TOTAL | 11 | 88 | 60 | 47 | 56 | 79 | 126 | 69 | 58 | 58 | 65 | 717 |
One hundred and seventy one (23.8%) of the articles gave fluoride equal credence. Overall, 435 (60.7%) of the articles contained at least one positive statement about fluoride.
Seventy nine (18.0%) of tabloid and 31 (11.2%) of broadsheet articles were of a negative only slant.
Table 2 shows a list of side-effects of fluoride printed in the tabloids and broadsheets.
| Fluorosis | 97 | 20.5% |
| Cancer | 77 | 16.3% |
| Bone Disease | 50 | 10.6% |
| Alzheimer's/Dementia | 45 | 9.5% |
| Osteoporosis | 33 | 7.0% |
| Infertility | 21 | 4.4% |
| Renal Interactions | 17 | 3.6% |
| Enzyme Interactions | 17 | 3.6% |
| Muscle Weakness | 16 | 3.4% |
| Skin Absorption | 13 | 2.7% |
| Poison/Toxicity | 13 | 2.7% |
| Diuresis | 12 | 2.5% |
| Bone/Hip Fracture | 12 | 2.5% |
It could be considered that the tabloids had tended to be more sensationalist about side-effects, this being reflected in the number of negative only articles being higher for the tabloids, 18.0% compared with 11.5%. Both broadsheets (24.9%) and tabloids (23.0%) had very similar numbers of articles with no slant.
Fluorosis is the most often cited side-effect and is mentioned 97 times. A systematic review carried out in 20075 by the Australian National Health and Medical Research Council (ANHMRC) identified 5418 scientific papers relating to the efficacy and safety of fluoridation. From this it was deduced that, with fluoride in tap water at 1ppm, the development of fluorosis was possible. However, where it did occur it would be mild and not cause sufficient aesthetic deterioration to require treatment.
Another systematic review in 20006 (sometimes called the York Report) estimated the prevalence of fluorosis, with water fluoridation at a concentration of 1ppm, to be in the order of 48%. Both studies found that, in order for one additional person to develop fluorosis, six others would need to be exposed.
Studies have shown that exposure to fluoride in any delivery system reduces caries.1,2 However, it is stated 35 times in the newspaper articles that fluoridation has no discernible effect.
The findings of the York Report6 were that previous studies used to assess the effects of fluoride on dental caries were poorly designed. Many were found to have inappropriate or no analyses of the data. Similarly, potentially confounding factors were not identified or controlled.
The conclusion was that, although fluoridation increased the number of caries-free children and lower mean dmft/DMFT scores, the degree of the reduction was not quantifiable.
These findings are regularly quoted in the newspaper articles and used as a potential argument against fluoridation.
The 2007 ANHMRC systematic review5 states that:
Existing evidence strongly suggests that water fluoridation is beneficial at reducing dental caries.
It uses the York Report as a reference to back up this statement. However, the York Report states ‘best evidence suggests’ that fluoridation reduces dental caries. To state that the York report ‘strongly’ suggests anything, as the ANHMRC review does, is an exaggeration.
What can be concluded from the systematic reviews is that fluoridation will reduce dental caries by varying amounts, depending on the circumstances of the person receiving it. It is therefore inaccurate for newspapers to suggest that fluoridation has no impact. Given that over 60% of the newspaper articles accurately report the beneficial effects of fluoride, it seemed counterproductive when they questioned its uses in the very next sentence, as some of the articles did.
Cancer can have potentially devastating effects and, as such, occupies column inches regularly. The risks of fluoride causing cancer are mentioned 77 times in the newspaper articles.
Studies have shown no association between water fluoridation and death from any cancer, or specifically from bone or thyroid cancer.5,7 It is probably safe to assume the same of fluoride in other delivery systems. Studies in the ANHMRC systematic review5 show a small variation either side of no effect in the numbers of cancers where there is fluoridation.
The incidence of cancer in young males is mentioned in some of the newspaper articles. This may be as a result of a study carried out in the US8 which reported an increase in osteosarcoma in young males where there was water fluoridation. Reassuringly, large populations have lived for generations in areas of some countries (Africa and India) that would be considered to have excessive fluoride levels, with no proof of an increase in mortality from cancer that was linked with fluoride.9,10,11,12
Osteoporosis is mentioned 33 times in the articles. Bone and hip fractures are mentioned twelve times, and ‘bone disease’ is mentioned 50 times.
It is possible that ‘bone disease’ as quoted in many newspaper articles could relate to osteosarcoma as it is such a non-specific term, but it is not clear from the articles. The ANHMRC systematic review5 included three other systematic reviews which have concluded that fluoride at a concentration of 1ppm neither increased nor decreased the risk of bone fractures.
It has been established that, though not necessarily causative, aluminium is involved in the aetiology and pathogenesis of Alzheimer's disease.13
A study in China noted that, when the urinary fluoride levels in children in two different villages were compared, those with higher urinary concentrations had significantly lower IQ.14 Confounding factors, such as family histories, social status, general health, and others were identified, and it was concluded that the lowering of IQ could only be as a result of the much higher concentration of fluoride in the drinking water in one village. The article14 mentions in the discussion that fluoride can be a significant neurological toxin because fluoride can form highly lipid soluble complexes with aluminium. These aluminofluoride (AlF3) complexes then interfere with the formation of nerve and vascular tissue in the brain.
Given the known toxicity of aluminium to nerve tissue,15 and the potential for neurological impairment with long-term aluminium exposure at very low doses,16–19 it may be that the results of this study do not adequately investigate the possibility that aluminium and not fluoride is the causative agent.
In 1988 in Camelford in Cornwall, 20 tonnes of aluminium sulphate was accidentally dumped into the local water supply. A study of this incident in the British Medical Journal in 199920 concluded that:
…people exposed have suffered considerable damage to cerebral function.
It has been suggested that very high concentrations of fluoride in drinking water could be preventive against Alzheimer's disease. The mechanism for this being that fluoride competes for absorption against aluminium in the gut.21
The newspapers may concentrate on these topics because they are health matters very much to the forefront of public conscience. However, the most recent evidence suggests that there is no conclusive proof that fluoride has any effect on human intelligence.22
It has been shown that the motility of human spermatozoa decreases with in vitro exposure to fluoride.23 In the study, the spermatozoa are exposed to fluoride at concentrations of 25, 50 and 250 nM at 5, 10 and 15 minute intervals. Similarly, studies using mice have found that the fertility of mice decreased when they were given drinking water containing fluoride at concentrations of 100, 200 and 300 ppm.24
In areas of endemic fluorosis in India, there is an increase in the prevalence of male infertility.25 Exposure to high levels of fluoride in drinking water are associated with decreased birth rates.26 All of these studies have a common feature, which is an exposure to much higher levels of fluoride than would normally be expected. Can one assume that, just because fluoride at a level of 300 ppm causes increased infertility, that fluoride at 1 ppm will do the same? Moreover, is it safe to assume that sterility in mice can be compared with likely effects in humans?
Various ranges in dose for a probably toxic dose (PTD) have been reported but a consensus would seem to be 5 mgF/Kg body weight.27,28 If one assumes the average 5–6 year-old to weigh 20 Kg, this means that the ingestion of 100 1.0 mg fluoride tablets would be a potentially lethal dose. The lethal dose for a 70 Kg adult would be 5–10 g taken orally. The side-effects of a toxic dose of fluoride can include:
The American Association for Poison Control Centers (AAPC) have reported that young children make up 90% of cases referred to it for potential poisoning with fluoride from dental products.29 In this respect, during the administration of acidulated phosphate fluoride (APF) gels in paediatric departments, children occasionally vomited.30 Parents should therefore be made aware that this could be an early symptom of fluoride poisoning, and medical attention should be sought. Children are most at risk of acute excess. Minimizing these risks is important, given that some high fluoride dentifrices, such as Duraphat™ 5000 could provide potentially toxic levels of fluoride to the very young.
In order to minimize risks to young children:
Accumulation of fluoride in brain and muscle tissue31 in mice has been shown to inhibit enzyme systems associated with:
However, this is a specific laboratory experiment that seems to bear little resemblance to the realities of fluoride exposure in humans. Nevertheless, it is a potential source of data for newspaper articles, but the general public would need better information in interpreting such results.
One hundred and twenty six articles were written in 2003, the highest annual number (17.5%). This is almost double the mean number for the other years, 1999 through to 2008.
In 2003, the 2003 Water Act was passed by Parliament. This gave the 28 Strategic Health Authorities the power to order water fluoridation. It also indemnified the water companies against legal liability if fluoridation was carried out. This may be the reason that the number of articles relating to fluoride and fluoridation increased in this year compared with other years, as the mass medication argument is a contentious issue. Mass medication was mentioned 81 times in the newspaper articles. The valid arguments put forward, particularly in the broadsheet newspaper articles, were very reasoned, logical, and non-sensationalist.
The legal definition of a medicinal product in the EU (Codified Directive 2004/27/EC, article 1.2) is any substance or combination of substances:
…presented as having properties for treating or preventing disease in human beings or which may be used in or administered to human beings either with a view to restoring, correcting or modifying physiological functions by exerting a pharmacological, immunological or metabolic action.32
Similarly, fluoride has been ruled to fall within the Medicines Act 196833 and, as such, is subject to the rigours of science that any other drug would be.
Caries rates in the UK population have decreased significantly and the use of fluoride toothpaste is the main reason for this reduction.34
However, the patterns of use of fluoride toothpaste vary between socioeconomic groups.35 The proposed fluoridation of tap water, in areas such as Southampton, is aimed at reducing caries rates in vulnerable socioeconomic groups, particularly children and adolescents. Pre-school children in these groups, and certain ethnic minorities, exhibit higher caries rates than the rest of the population, and this disparity is increasing.35 The beneficial effects of fluoride will only combat caries to a finite extent. Though it is possible to educate people about the need to use fluoride and cut down on sugary food, it is far more difficult to change their behaviour.
The York Report6 concludes that inequalities in dental health across social classes in five and twelve year-olds are reduced with water fluoridation. But it also suggests ‘caution’ in interpreting the results because the quality of the evidence in the studies it used was deemed to be ‘low’. Given this, and the fact that the prevalence of fluorosis of aesthetic concern with 1ppm fluoride was estimated at 12.5%,6 it is understandable that some feel fluoridation is unwise.
However, in large populations, such as North America, which have had fluoridation for many years, it would not appear that significant fluorosis is a common problem.36 This could reflect a change in habits and behaviour to avoid excess fluoride in a knowledgeable populous, but this seems unlikely given the wide socioeconomic groups involved.
Access to primary dental care via the NHS is difficult in some regions.35 However, access to dental treatment alone will not reduce the inequalities in caries experience. Prevention of caries would seem to be one instance where merely providing more dentists is not necessarily the answer. It has been found that providing more dentists for disadvantaged groups has poor cost:benefit ratio (though this is not the case for the elderly). It is the implementation of appropriate oral health policy, not dental treatments, that is required to address the causes of oral diseases.35
To this end the 1988 Acheson Report37 concluded, amongst other things, that:
But again, without changes in behaviour and attitudes of the population, there is only so much that can be achieved.
Fluoride is a common topic in newspapers. Accurate reporting of the beneficial effects of fluoride is often accompanied with reporting on its harmful side-effects, particularly in tabloid newspapers.
Better dissemination of up-to-date research to the popular press appears indicated in order to allay some of the unfounded fears surrounding the use of fluorides in dental prevention, particularly fluoridation. Similar scare stories surrounding the MMR vaccine have led to decreased uptake and the re-emergence of a once all but eradicated disease in the UK.
