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(05/01/16) A summary of 'Cochrane Collaboration systematic review of water fluoridation 2015' has been posted in Reports.
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(16/04/14) A critique of 'One in a Million: The Facts' has been posted in Reports.
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(16/04/14) 'Fluoridation: Popularity' has been posted in the Archive.
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(18/04/10) New fluoridation scheme for Southampton


(18/04/10) The Reports and Archive sections have been updated with further documents and links


(11/07/09) A critique of Prof. Newton's report to South Central SHA has been posted in Reports.
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(28/09/08) A critique of the South Central Strategic Health Authority Consultation Paper on Water Fluoridation in Southampton, has been posted in Reports.
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(07/09/08) A response to the Chief Dental Officer's 'Dear Colleague' letter of guidance for new schemes, endorsed by scientists from the York review, has been posted in Reports.
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(23/06/08) Isle of Man has announced on 12th June that it will not be fluoridating its water supply
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South Central Strategic Health Authority Consultation Paper on Water Fluoridation (2008): A Critique

1. Introduction

1.1 Consultations have begun in the Southampton area on fluoridating the local water supply. The City's Primary Care Trust, which made the request, and the South Central Strategic Health Authority, with whom the decision will rest, have each issued documents setting out their case.

1.2 Both documents present problems for the reader looking for impartial information. Neither gives a balanced scientific account of the evidence for the safety and effectiveness of fluoridation. Facts and figures are presented selectively, and not always accurately, to show the case for fluoridation in a good light. The PCT's leaflet is the more obviously propagandist. This paper principally addresses the SHA's document which deserves careful scrutiny. The Reports and Archives sections of the website appgaf.org.uk give additional background to some of the issues surrounding fluoridation.

1.3 The author of this paper was a member of the advisory panel to the systematic scientific review conducted by the NHS Centre for Reviews and Dissemination at the University of York in 2000, the 'York' review, and is Co-Chair of the All-Party Parliamentary Group Against Fluoridation.

2. The Consultation Paper

2.1 The SHA's document is clearly presented, and is helpful about procedures and stages of the statutory consultation. It claims to set out "all the facts" about fluoridation (1.7), which is clearly not possible. It speaks of taking into account "robust scientific evidence" (2.7), which is also hard to obtain as will be seen below. Its claim to "[summarise] the medical and scientific evidence on the safety of fluoridation" (2.8), notably omitting its effectiveness, is the chief concern of this paper. The SHA is right that a key task is to "separate the facts from the myths" and give "accurate information" (4.1).

2.2 The SHA is also right to put "greatest emphasis on the results of good quality reviews of all available relevant scientific research" (4.4), and to state that "Selective quotation of individual results can be very misleading". This approach lies at the heart of good decision-making in health matters, and does much to eliminate the bias that is the enemy of scientific enquiry, and that has been endemic in the fluoridation debate from its beginnings. It is especially troubling that the SHA does not observe its own advice in this consultation paper.

2.3 The Evidence

2.3.1 One of the key issues is the status and findings of the York review, and it is important to understand fully what this means. Much of the bad science on fluoridation since 2000 comes from a failure to grasp this. The concepts are not difficult.

2.3.2 How can public health professionals, let alone the lay public, tell where the truth lies among a welter of scientific studies? Clearly enough, this happens by collecting and analysing all the relevant studies, paying careful attention to their quality and quantity, and bringing them together into a general review from which conclusions can be drawn. But just as the quality of primary studies varies, so too does that of reviews. A reviewer who does not know where to look, or lacks rigour, or has a personal interest in the outcome, may include or exclude studies for reasons that seem good to him or her, and produce a result that does not reflect the true state of the evidence, without the reader being any the wiser.

2.3.3 There is in fact a hierarchy of reviews, as there is of studies with their varied methodologies. At the top is the systematic scientific review, the pinnacle of evidence-based medicine. Even these are not uniform in quality. The Government funded the York review with the aim of putting an end to the uncertainties about fluoridation, acknowledging that much of the evidence did not meet modern standards. York was, surprisingly, the first and only systematic review that looked at the world literature of all human studies into water fluoridation. As such it adhered to internationally recognised criteria for selecting, assessing and grading the evidence, giving both rigour and transparency to a process in which every reader can see what studies were included and why, as well as - crucially - how reliable the evidence is.

2.3.4 York took the process further in opening its website to anyone who felt they had something to contribute to the evidence. And the team of expert reviewers, working for many months, were uniquely assisted by an advisory panel drawn from leading proponents and opponents of fluoridation, together with some distinguished scientists with no connection to any group or faction. The measures taken to guard against bias were exceptional, even for a systematic review.

2.3.5 One consequence of its quality is that York has rendered all previous reviews that looked at the same questions obsolete. It is no more legitimate, for example, for a scientist to rely on contrary findings from earlier 'narrative' reviews, than it would be for a lawyer to cite an old county court judgment when the House of Lords has pronounced on the question. Nor is it productive to second-guess York's assessment of a study, at least without compelling evidence. Unfortunately, there are surprisingly many in the field of health who are still not fully aware of the status of a systematic review and all that this implies, or who do not wish to accept the implications.

2.3.6 Anyone can check on what York found by going to its websites www.york.ac.uk/inst/crd/fluoridnew.htm and www.york.ac.uk/inst/crd/fluorid.htm. Its main messages were of uncertainty over all the questions investigated, including fluoridation's effectiveness which nevertheless looked probable. The reviewers were surprised at the moderate-to-low quality of the evidence, especially for something so heavily promoted among English-speaking countries: they could not find one reliable study ('level A') in 50 years of fluoridation. A key message was the need for high standards in fluoridation research. The weaker the study, methodologically speaking, the more likely the findings will be due to bias or chance. It is a seeming paradox of fluoridation that the one source of reliable evidence has shown how unreliable all the evidence is. There is no "robust" evidence to be had. The only thing that is certain at present is uncertainty.

2.3.7 A second systematic review of high quality was conducted in 2007 by the Australian National Health and Medical Research Council, which examined recent publications only with the aim to "update the most relevant existing systematic review", i.e. the York review. Because of its quality the York report formed the basis for the report from the NHMRC, which saw no reason to depart from its findings under any heading. A number of post-2000 studies were identified, none of good quality, which did not alter York's verdict or resolve any uncertainties. This is an important point when considering 2.3.14 below. The Australian review did not cite the UK's Medical Research Council fluoridation report of 2002, quoted by the SHA, since this did not have the reliability of a systematic review.

2.3.8 Keeping this background in mind, as well as following the good practice of normal scientific enquiry, one can see that South Central SHA's presentation falls down in many ways. It says nothing to guide the public on how to reconcile conflicting evidence from reviews, or to explain the unique reliability of York. The Government, however unwelcome it found York's conclusions, at least continues officially to acknowledge York's primacy. The SHA shares in a general failure to distinguish between good evidence and bad; this will make the public's task doubly difficult. Several of its references cite sources which conflict with York, as will appear below. Others are misquoted or do not support the SHA's argument.

2.3.9 Among the SHA's more serious errors is the claim that York "found no evidence that fluoridation has harmful effects on health" (4.4). This is not even correct in the sense of an "absence of evidence", in contrast to "evidence of absence". Professor Kleijnen, who headed the review team, wrote in the British Medical Journal on 16th June 2001: "We have been assiduous in our paper, our full report, and our contacts with the media, not to convey a message of no evidence of harm". The sections of the York report on bone problems, cancer, Down's syndrome, congenital defects and other conditions contain studies suggesting links with all these things. A typical finding is "Whilst there were 11 analyses that found ..fewer cancers . , a further 9 analyses found ..more cancers . , and two studies found no effect" (York 9.6). The full, picture, however, is that the studies pointed both ways, and were almost all of poor quality ('level C') as well as quantity. A more recent American review (see 2.3.20 below) has similarly described the cancer evidence as "tentative and mixed". For an SHA to call this "no evidence" of harm is unscientific, and seeks to give the public false reassurance. Some people would find the fact that no reliable safety studies have been done enough to sway them against any local fluoridation scheme.

2.3.10 Readers will be confused by the SHA's account of "The benefits" in 4.5.1, in particular as to how York's findings "confirmed" specific figures for reductions in tooth decay when the review was "critical of the quality and quantity of the research available". Both statements cannot be true. If the primary studies were weak and few, then no clear conclusions can be drawn. "To have clear confidence in the ability to answer the question [on effectiveness]" wrote the reviewers in York 4.9, "the quality of the evidence would have to be higher". The Medical Research Council's report referred to by the SHA, while over-optimistic about fluoridation, likewise called for studies to "estimate ..the effects of water fluoridation on children.." (MRC, 6.6).

2.3.11 Also in 4.5.1, the SHA should have highlighted the extreme weakness of the evidence for reduction in dental inequalities between social groups and areas when it argued for help for disadvantaged communities. York's validity score for this evidence overall was 1.6/8, the lowest in the whole review. The independent scientists on the advisory panel have described the evidence as "weak, contradictory and unreliable". The public needs to be able to judge whether this is a sound or responsible basis for a health policy which will give a relatively high concentration of fluoride to nearly 200,000 people, many of whom will not want it.

2.3.12 The SHA in 4.5.1 disregards its own warnings (4.4) against selective quotation and in favour of good-quality reviews, by highlighting one 19-year-old study to illustrate fluoridation's benefits to adults. York found only one acceptable ('level B') study on adult teeth in the literature; but it was not this one. (Another small 2007 systematic review looking at adults only and various sources of fluoride gives no grounds for revising York's verdict; York reviewers have pointed to its weaknesses in selection and statistics.) This is the sum of the relevant evidence for adult benefit, which falls far short of supporting the SHA's confident claims. The SHA warns in 4.7 against accepting evidence from one study.

2.3.13 Southampton readers should be aware that "adjusting" the level of their fluoride (3.0; 4.5.1) means increasing it by a factor of 12.5, from 0.08 to 1 part per million. "Adjusting", together with an "optimum" level of fluoride (4.2), are terms often found in pro-fluoridation literature; neither is a fair description, and the latter lacks scientific validity.

2.3.14 It is not clear why the SHA, which explicity supports good-quality reviews, does not refer to York when considering unsightly mottling of teeth in fluoridated areas (4.5.2), while it quotes the MRC and Australian reviews as estimating a population prevalence of 3% - 4%. York's estimate, having taken careful account of several factors including different climates, altitudes and kinds of water, was 12.5%. This is of course a discouraging figure for those who promote fluoridation. To omit it is to withhold the best scientific evidence available. In fact the Australian review, while finding 8 more recent studies of poor quality which included some lower values, found the results "consistent with ..existing systematic reviews" (Executive Summary, page 10), chiefly York. The SHA has thus adjusted the evidence in favour of an inferior review while disregarding or misquoting the two most reliable sources of evidence. (The SHA's page reference to the NHMRC under 6.9 is also incorrect.) Furthermore the "3 - 4%" claim beneath the pictures in 4.5.2 is grossly inaccurate, and conflicts with fluorosis figures given two paragraphs earlier which related to more unattractive mottling. York's estimate of all fluorosis under fluoridation schemes is roughly 1 child in every 2 (48%), a figure concealed by the SHA through its confusion of low and high degrees of fluorosis. The "Very mild" fluorosis pictured may thus involve anything up to 1 in 3 children. York's figures suggest that the numbers of people fluorosed by fluoridated water may be roughly similar to the numbers of people helped. Southampton can expect, not a "relatively small", but a substantial increase in children with fluorosed teeth if their water is fluoridated, not least because the local fluoride concentration will be increased more than twelve-fold.

2.3.15 To describe dental fluorosis (mottling) as a "cosmetic condition" (SHA 4.5.2) is a partial truth. York was careful not to make this assumption. The Government in a written parliamentary answer in the House of Lords on 20th April 1999 described it as "a manifestation of systemic toxicity". If the public are to be offered "all the facts" about fluoridation, accuracy here might be thought relevant.

2.3.16 There are two studies that have figured prominently in pro-fluoridation literature since York, both being selected to offer reassurance on the safety of fluoridated water. One is Hoover (1991) on cancer; the other is Hillier (2000) on bone fractures. They are both 'level C' studies (i.e. "lowest quality of evidence, high risk of bias"), with validity ratings of 3.3 and 4 out of 8, and for this reason were given no special weight by York in its overall finding of "no clear association" with either condition. Both are cited by the SHA (4.6 reference [10], and ?4.7), despite its earlier warning that selective quotation of individual results "can be very misleading" (4.4). Other studies, of comparable or better quality, could have been cited to give an opposite picture. (There is some confusion about Hillier, since although it appears among the references at the end (6.16) there is no corresponding "[16]" in the text, and the paper cited was not the one in the York report and does not seem to have appeared in any refereed journal, so that its quality is impossible to judge.)

2.3.17 The Knox review of cancer more than 20 years ago (4.6), which claimed that fluoridation could not cause cancer, was not a systematic review and has not stood the test of time. The SHA stresses the need to be guided by good-quality reviews (4.4).

2.3.18 There are serious inaccuracies in the section of 4.6 that looks at bone and bladder cancer. Neither of the references [13] or [14] supports what the SHA claims. [13] is not in fact the "larger study" by Douglass, said to refute any risks of bone cancer in young males. That study, as the SHA should have known and stated, has not been published. The reference is merely to a published letter advising caution and the need to "await the publications from the full study". In anticipating a firm finding of no link with osteosarcoma the SHA misleads its readers. The non-appearance of Douglass's claimed refutation of the Bassin study, after a further two years, must raise some doubt about his claims. The first author of the paper on bladder cancer [14] has recorded her concern in an e-mail about inaccuracies in the SHA's account of this study in 4.6. She writes "I believe that the information they provide to the public should be correct". The study did not address osteosarcoma as stated.

2.3.19 The SHA's treatment of fluoridation and bone fractures (4.7) needs comment. While it does not misrepresent the overall trend in writing of 12 studies, where York examined 18, its decision to highlight one study which suggested that fluoridation protects strongly against fractures, while cautioning in the same paragraph against putting weight on one study, may make the reader question where the SHA's agenda lies. The study did not in any case meet York's inclusion criteria, even for 'level C', and by the standard of good-quality reviews which SHA endorses in 4.4 it is scientifically worthless. Again the SHA writes incorrectly of "no evidence" of increased hip fracture risk, this time citing the Medical Research Council whose working group (not its Environmental Epidemiological Unit as stated in the text) covered substantially the same ground as York.

2.3.20 A major review which might have been included for its rigour, thoroughness and relevance, although it was not a systematic review, is the 2006 enquiry into possible harms of fluoridation by the US National Research Council of the National Academy of Sciences, at the request of the Environmental Protection Agency ('Fluoride in Drinking Water: A Scientific Review of EPA's Standards'). It collected and reviewed the evidence for three years, and it was cited by the Australian NHMRC systematic review. It was concerned enough about possible risks to bone strength, IQ, brain chemistry and function and thyroid function among others to recommend that the Maximum Contaminant Level Goal in the USA should be lowered from 4 parts per million. This is 4 times the normal level of artificially fluoridated water; but with variations in people's drinking patterns between 0.5 and 10 litres a day, and wide differences in individual responses to ingested substances, this is a narrow margin in toxicological terms. The US report sounded warning bells in emphasising that, on a per-body-weight basis, infants and young children have 3 - 4 times greater exposure to fluoride than adults. The American Dental Association has suggested that mothers should consider avoiding fluoridated water when making up infant formula for bottle-feeding. This is an important and relevant development which the Southampton public should be aware of when considering "all the facts".

2.3.21 The SHA's references to future research are general (4.4; 4.5.1; 4.8), and do not reveal many of the facts. Those concerned about fluoridation would wish to know that York included infant mortality, congenital defects and IQ deficits as areas needing more research; the MRC highlighted the total exposure to and uptake of fluoride from all sources, with an eye to be kept on fluoridation and cancer rates; the US NRC recommended assessment of total fluoride exposure, risks of bone fracture and skeletal fluorosis, and "emerging health parameters of interest (e.g. endocrine effects [such as thyroid] and brain function)" as well as IQ. This is a selective list from a wider spread of recommendations, designed to show that none of the three major reviews of this decade is satisfied about safety. Nothing in the SHA's document would alert a reader to this, or to York's suggestion for researching a lower concentration of 0.8 parts per million of fluoride. The chair of York's advisory panel has written publicly: "The review did not show water fluoridation to be safe." (This is not to say that it was shown to be unsafe.)

2.3.22 The SHA is selective in its presentation of the ethics of fluoridation (4.9.2-3). Reliance on the opinion of one parliamentary campaigner, Lord Avebury, is not "robust" evidence; nor is the citing of one legal verdict to the exclusion of others which have taken a different view. The ethical problem is not spelled out for the reader. This is not a matter of "personal choice" as such: it is specifically whether it is permissible to give someone a therapeutic substance, which makes medical claims, without obtaining their individual informed consent. The answer in the context of a doctor's surgery is plainly No: the General Medical Council, following accepted conventions in western society, is explicit on the point. The question is, can there be exceptions in the realm of public health?

2.3.23 Appropriately, the recent report from the Nuffield Council on Bioethics is cited, a reputable body drawn from a number of disciplines. The report was valuable, but its thrust towards certain state interventions in individual health choices did not escape criticism when it appeared. There were arguments in the case of fluoridation that it did not consider, and the omission of a key document, the Council of Europe Convention on Biomedicine, was unfortunate. Under the latter fluoridation would not feature under the rare public health exceptions to the general ethical requirement of consent. There is also an absolute ban under the Convention on research on subjects who have not individually consented. This is not the place for a detailed argument, but there is more than one tenable view on the ethics and the SHA's treatment of the issue is slight and not well directed. (Readers who wish to look further can see a critique of Nuffield in the Reports on this website, appgaf.org.uk.)

2.3.24 Organisational support for fluoridation is a more complex matter than the SHA outlines in 4.10. In much of the English-speaking world there is strong professional support, dating from long before the time when the true state of the evidence became known. The All-Party Group that the SHA cites is not however a "professional health organisation". It is an unofficial group of MPs and Peers, which allowed itself to be visibly linked to organised dentistry in the setting up and drafting of its report, while the dental lobby were among the principal witnesses at its enquiry. The report was also unscientific in other ways. (See under Reports at appgaf.org.uk.)

2.3.25 Fluoridation is a minority pursuit in world terms (4.3). Readers will note that only supporting organisations and countries have been cited in the SHA's account, which claims to review "the experience of existing fluoridation schemes ..around the world" (2.8). The public, in search of a balanced picture, would be interested to know that, for example, many US cities have given it up, many countries have rejected it for a variety of reasons including doubts about health and the environment, and the former Czechoslovakia, DDR, Finland, Japan, Netherlands, Sweden, Switzerland, USSR and West Germany all ceased to fluoridate after many years. Eire, a rare fluoridating country in Europe, has recently lowered its concentration of fluoride by 30% out of concern about fluorosis.

2.3.26 The supporting bodies listed in the SHA's 4.10, and many more besides, signed up some years ago with the National Alliance for Equity in Dental Health as campaigning organisations for fluoridation. This makes the impartiality of most of the information now coming from 'official' sources, notably in dentistry and public health, highly problematic. There is a long-standing fluoridation culture from the early days, extending to Government, whose influence results in consistently over-optimistic presentations of the evidence.

2.3.27 Some of this was brought out in an informative article in the British Medical Journal of 6th October 2007 by three respected figures in evidence-based medicine (Cheng et al, 'Adding fluoride to water supplies': see under Reports at appgaf.org.uk), where they write of "one sided handling of the evidence" and express concern "that the polarised debates and the way that evidence is harnessed and uncertainties glossed over make it hard for the public and professionals to participate in consultations on an informed basis". They characterise the Department of Health's objectivity, in the polite language of science, as "questionable". As one example of uncertainty they point out that the Hillier study favoured by the SHA (see 2.3.16 above) would have less than one chance in five of detecting 10,000 excess hip fractures a year in England if the population were exposed to fluoridated water at 0.9 ppm or higher. This illustrates the difficulty in detecting harms among populations.

2.3.28 There is no consideration of the environment in the presentation. Denmark and Sweden were influenced against fluoridation by fears of possible environmental damage. This is a relevant factor. The SHA in 2.8 states that it "Considers some of the ..environmental issues around water fluoridation". It does not. Perhaps this was overlooked in the proof-reading.

2.4 The Target

2.4.1 The consultation paper makes its case for the benefit to children on the basis of figures for decay in 5-year-olds (2.3; 2.10). It is normal when presenting evidence for children's dental health to include 12-year-olds in the statistics, and it is puzzling why the SHA has not done this. Figures for 12-year-olds are the more usual measure as they relate to permanent teeth. If these figures are more reassuring than those for 5-year-olds this could make the case for fluoridation less persuasive.

2.4.2 The SHA claims (1.5) that "An independent study [1] ..estimates that over 36,000 teeth can be saved in the next 20 years" if fluoridation is agreed to. This is wrong. Reference [1] shows that Abacus International wrote in their report: "Water fluoridation is expected to result in ..a total of 36,032 carious lesions avoided". There is a major difference between lesions saved and teeth saved. Pits in teeth are easily filled, and the number of actual teeth saved from extraction will be far smaller than the 36,000 quoted. This has implications for the SHA's costing of fluoridation's benefit over 20 years, at 32p per tooth (3.6): since this figure is based on lesions and teeth being the same, and overlooks the fact that teeth can have more than one lesion, the cost will in fact be greater. Abacus stresses that its findings throughout "rely on data provided by South Central SHA", which also limited its scope to fluoridation's impact on dental health. Readers may wonder by this stage what reliance can be placed on the SHA's treatment of data.

2.4.3 Dental decay in adults is referred to in SHA's 2.3. As explained in 2.3.12 above, the evidence for benefit to adults is minimal. It is now known that most effects of fluoride are produced topically, i.e. on contact with the teeth, and not through swallowing it as was previously believed. This too makes fluoridation less attractive than it might once have appeared.

2.4.4 A further consideration is that, as the incidence of decay has fallen markedly among 12-year-olds in EU countries regardless of fluoridation (according to WHO oral health statistics), so the possible effects of fluoride in water have levelled out. There may not be much scope for improvement by this method at today's relatively low levels of decay in Southampton and elsewhere. What is certain is that something other than water fluoridation has greatly reduced many European children's dental decay since the 1970s.

3. Other consultation documents

3.1 The Southampton City PCT's leaflet 'Key Facts About Fluoridation' shows a disregard for balanced presentation and a selective treatment of evidence that border on the reckless. There can have been few more one-sided accounts of the fluoridation issue outside the publications of the British Fluoridation Society. Any reader who understands the basic elements of scientific enquiry will have little difficulty in assessing the value of the information provided.

3.2 The Chief Dental Officer issued guidance on consultation schemes to all major public health bodies in a 'Dear Colleague' letter in February 2008 (Gateway 9361). These cannot but influence the stance of any PCT and SHA contemplating fluoridation. His presentation of the background and evidence reflect the Department's long-held support for fluoridation, and is open to challenge on several points. A critique of this by the present author, endorsed by Sir Iain Chalmers and Professor Sheldon from the York review, can be found under Reports at appgaf.org.uk.

4. Conclusion

4.1 "Cogency" and "evidence-based" arguments are what is being demanded from the public in this consultation. It is very worrying that South Central SHA should have shown such a partial grasp of how evidence should be presented, and been guilty of so many errors. On most pages of its consultation paper there are examples of inappropriate citations, exaggerations, omissions, selective quotation, carelessness with references, or other inaccuracies. These are not random in their effect: without exception they go to bolster the case for fluoridation. This is an unreliable and one-sided document, made worse by its claims of scientific respectability.

4.2 An SHA has a statutory duty to monitor and report on the health of its fluoridated populations (4.8). If South Central cannot control its evident bias in favour of fluoridation, there is little prospect of any good science being conducted which might show up health problems from a local fluoridation scheme. This must be worrying for inhabitants of Southampton and the three other local authorities.

4.3 The public deserve better. If this paper contributes towards alerting readers to the flaws in the information they receive, and putting them on guard against selective argument from wherever it comes, it will have served its purpose.

Edward Baldwin.
7th October 2008.

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