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Open letter to Lisa Hansen on NZ Fluoridation Review Ken Perrott Mar 03

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Dear Lisa,

There are mistakes and misinterpretations of the scientific literature in your recent open letter to Sir Peter Gluckman and Sir David Skeggs. The letter also misrepresents the NZ Fluoridation Review (Eason et al., 2014) and the Fluoride Free NZ (FFNZ) report criticising that review. It gives the latter report more credibility and status than it deserves.

I am responding with an open letter of my own because I think the mistakes and misrepresentations need correction. I hope you receive my critique with the respect for the scientific openness,  criticism and healthy discussion you assert in the last paragraph of your letter. That certainly describes my approach and in that light I offer you a right of reply on my blog to this open letter.

First I consider some aspects of the way you present the NZ Fluoridation Review and the FFNZ report.

Citing the NZ Fluoridation Review

You generally cite Health Effect of water fluoridation: A review of the scientific evidence (Easton et al., 2014) as  the “Gluckman/Skegg report.” I realise you does this because your clients, and particularly the Fluoride Free NZ activist group, have adopted that terminology. It is however disrespectful to the real authors of the review. Such reports are not usually attributed to the heads of institutes or organisations.

Nature of the NZ Fluoridation Review

You unfairly compare Easton et al., (2014) to other major reviews in terms of cost, time taken, processes and the publication period reviewed. You are simply citing the activist FFNZ report which set out to discredit the NZ Fluoridation Review in any way possible.

The Fluoridation Review describes its approach in this way:

“Several previous rigorous systematic reviews were used as the basis for this analysis, and literature searches in Medline, EMBASE, the Cochrane library database, Scopus, and Web of Science were undertaken to identify subsequent studies in the peer-reviewed scientific literature. Alleged health effects from both the scientific and non-scientific literature were considered, and many original studies relating to these claims were re-analysed.” [My emphasis].

The Review’s purpose was not to duplicate the previous extensive reviews on this subject. It instead summarised them and reviewed later research. In other words the goals were simpler and less costly. (Costs were in any case determined by the local bodies which commissioned and, together with the Ministry of Health,  paid for the review.)

The FFNZ comparison is disingenuous.

The FFNZ Report.

You promote the inaccurate self-description of the FFNZ report (Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report) as “international peer reviewed.” That is the impression FFNZ attempts to convey  but it is dishonest – all the authors and “peer-reviewers” are connected with, or work for, Paul Connett’s Fluoride Action Network and similar activist organisations in the US or NZ. I illustrate some of the links in the figure below taken from the blog article The farce of a “sciency” anti-fluoride report.

I have provided an in-depth analysis and critique of the FFNZ report in a series of blog articles which are available in a single PDF document (Fluoridation is safe and effective: A critique of Fluoride Free NZ’s criticism of The NZ Fluoridation Review).

Now, the substantive issues you raise in your open letter.

Endemic fluorosis, community water fluoridation and IQ

Up front we must be clear about the situations behind the various scientific studies on the issue of fluoride and IQ.

So far, the only study  directly relevant to community water fluoridation (CWF) is that of Broadbent et al., (2014). This studied populations in the Dunedin region over a long time period. Notably you do not refer to this study, despite its extensive nature and relevance to the issue at hand. In  fact you seem unaware of the research as you claim in your letter that the “impact on IQ from water fluoridation at between 0.7 and 1 ppm” is “as yet unmeasured!”

The studies you do cite (mainly Choi et al., 2012) are from areas of higher fluoride consumption. Most of the studies were from areas of endemic fluorosis – mainly in China. This means that the findings cannot simply be transferred to areas like NZ.

Choi et al., (2012) are clear about the criteria used for choice of studies in their metareview. They say:

“We specifically targeted studies carried out in rural China that have not been widely disseminated, thus complementing the studies that have been included in previous reviews and risk assessment reports.”


“Opportunities for epidemiological studies depend on the existence of comparable population groups exposed to different levels of fluoride from drinking water. Such circumstances are difficult to find in many industrialized countries, because fluoride concentrations in community water are usually no higher than 1 mg/L, even when fluoride is added to water supplies as a public health measure to reduce tooth decay.”

This is why the Choi et al., (2012) meta review is not directly relevant to CWF.

Choi et al., (2012) not relevant to CWF.

I can illustrate the difference between that situations reviewed by Choi et al., (2012) and the New Zealand situation where CWF is common using dental fluorosis data from the recent paper of Choi et al., (2015),  Our Oral Health (2010) and Beltrán-aguilar & Barker (2010) (see Water fluoridation and dental fluorosis – debunking some myths).

There is very little severe or moderate dental fluorosis in NZ and USA. But it is very common in the area studied by Choi et al., (2015) which is probably typical of the areas reviewed by Choi et al., (2012) and the Indian paper you cite (Saxena et al., 2012). Unfortunately most of the studies reviewed by Choi et al., (2012) are of poor quality (see below) and do not include data for many possibly confounding factors like severe dental fluorosis, pesticide use, etc.).

So – clearly different situations.

The metareview of Choi et al (2012) was a metareview of studies from higher fluoride areas – not a metareview of studies from all areas, or studies from areas where CWF is common. Their review is not directly applicable to situations where CWF is considered, like NZ and USA.

The authors have stated this themselves:

“These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S. On the other hand, neither can it be concluded that no risk is present.”

Note: I have suggested (Perrott 2015) that the small cognitive deficits report by the Choi et al., (2012) could be caused by severe dental fluorosis, and not directly caused by chemical toxicity. (I discuss this further below.) This is consistent with the results of Choi et al., (2015) who observed a significant relationship of cognitive deficits to severe/medium dental fluorosis but did not find a significant relationship with the fluoride concentration of the drinking water.

I believe researchers studying IQ effects in areas of endemic fluorosis should consider this hypothesis.

The “error” in the NZ Fluoridation Review

Your open letter concentrates mainly on an “error” in the NZ Fluoridation Review. This “error” was little more than a “typo,” occurred only in the executive summary (the body of the review reported the science correctly), and was corrected by the authors when brought to their attention. They also corrected at least one other error at the same time. I have discussed this in Did the Royal Society get it wrong about fluoridation?

Any publishing author is well acquainted with the problems of typos and similar errors. Despite the best proof-reading of drafts one inevitably finds some errors only after publication. (An example of Murphy’s Law, I guess.) This error has only become an issue because of the intention of activist organisations who wish to discredit the review.

It is worth noting that the Harvard University press release reporting the research concerned made exactly the same error and acknowledged and corrected it when pointed out. The current version now says:

“The average loss in IQ was reported as a standardized weighted mean difference of 0.45, which would be approximately equivalent to seven IQ points for commonly used IQ scores with a standard deviation of 15.*

** This sentence was updated on September 5, 2012.”

Yet, you, FFNZ and their associates do not criticise Harvard University!

Your mistaken description of error.

First, I will stress again that discussion of this “error” refers to the work of Choi et al., (2012) and areas where fluorosis is most likely endemic. That research does not deal with CWF or the situations where drinking water fluoride concentrations are that low.

The slide below, from a presentation made by Xiang (2014) at Paul Connett’s last conference in Washington, gives an idea of the situation in areas where these studies were made. Xiang is the author of several of the papers reviewed by Choi et al (2012) and commonly used by anti-fluoride activists in arguing against CWF.

This is clearly a different situation to New Zealand.

What did Choi et al (2012) actually report?

They report in their abstract “The standardized weighted mean difference in IQ score between exposed and reference populations was –0.45.” This is a standard deviation resulting from their analysis of 27 studies with different methods and quality of data. It is not a difference in IQ score.

This approach was necessary because the different studies reviewed had different IQ scales, different measurement methods and different levels of variation in the data. They standardised the differences by expressing them as a fraction of the standard deviation for each study. A mean value over all studies was determined, weighting the contribution from each study according to the precision of the IQ measurements.

Mistakenly, Harvard University and the NZ Review summary originally described this as an IQ score difference instead of SD. (Note – this mistake was not in the body of the NZ Fluoridation Review). In fact many readers were confused as the statistical process used by a Choi et al (2012) was not sufficiently well explained from a lay person’s viewpoint and they had to publish an extra explanation later (Choi et al., 2013).

Going from a standardised weighted mean difference value to a difference in IQ points.

Standard deviation is a function if variation in data so it is wrong to assume a value for all situations. It will be different for different sets of data.

The standardised weighted mean difference value of 0.45 has meaning because we know it represents less than half of one standard deviation so it indicates how it compares with measurement error. Many people have equated the difference of 0.45 to 7 IQ points. However, Choi et al., (2012)  did not report a difference of 7 you claim. This value came out of the explanation in Choi et al., (2013) in their response to a letter to the editor. They provided an example for a commonly used IQ scale normalised against a theoretical bell curve:

“For commonly used IQ scores with a mean of 100 and an SD of 15, 0.45 SDs is equivalent to 6.75 points (rounded to 7 points).”

This cannot simply be translated to any other IQ scale. For example these values would be inappropriate for the IQ scale used in Saxena et al., (2012)  study you refer to later in your letter.

The significance of the 0.45 standard deviation decrease in IQ points.

It is easy to throw around values of 7 and 15, as you do, but what is the significance of the result (for areas of endemic fluorosis – let’s not forget this study is not directly relevant to CWF). Choi et al., (2012) themselves warn that a decrease of 0.45 standard deviation “may seem small and may be within the measurement error of IQ testing.”

All this says is that many data sets, especially those with high variability, may not show a difference between children from high and low fluoride areas because the difference measured by Choi et al., (2012) is relatively small. In saying that I am not trying to deny any significance at all to their results. However, it is provisional and, as they say, it needs further confirmation. I think two points must be made here:

  1. The metareview was purposely biased towards studies from China and high fluorosis areas – many of which show endemic fluorosis. It is not directly relevant to the issue of CWF;
  2. The articles reviewed were in themselves mostly of poor quality, did not consider confounding factors and were often very brief (see figure). Not the fault of Choi et al., (2012) and hardly a surprising situation for the regions of interest, but this does help put the value of 0.45 standard deviation into context. It is, as yet, really only provisional.

Histogram showing size of the reports reviewed by Choi et al., (2012) from 

Your claim the Fluoridation Review misrepresented Choi et al (2012) in a specific quote.

Choi et al., (2012) themselves say:

“The estimated decrease in average IQ associated with fluoride exposure based on our analysis may seem small and may be within the measurement error of IQ resting.”

This is a valid assessment because the mean difference they observed amounted to only 0.45 of a standard deviation which can be related to measurement error.

The Review refers to this text (and quotes as section of it) as follows:

The authors themselves note the difference is so small that “it may be within the measure tn error of IQ testing.”

I really don’t see any misrepresentation there. The authors did note that the difference was small compared with measurement error.

In summary I reject your criticisms on this issue for these reasons:

  1. You have relied for claims on a metareview of studies from areas of endemic fluorosis. A study reviewing reports of mainly poor quality and which the authors had described as not relevant to areas using CWF.
  2. You misrepresent correction of the small mistake as a change in recognition of the science or a “misreading of the available evidence.” There was no change as the science was correctly reported in the body of the review – the mistake occurred only in the summary. Others have made similar  mistakes – including Harvard University in their press release.
  3. You repeatedly refer to an IQ point differences of 7 without at any time considering how significant this value is compared with the measurement errors.
  4. You imply that this issue was not thoroughly addressed, which is wrong as it was discussed in the body of the review. Correction of the mistake in the summary is all that was required.

But, I stress again, whatever the significance of the small IQ differences reported for areas with endemic fluorosis in these studies they are not relevant to areas like NZ where no IQ deficits have been reported for CWF. In fact, quite the opposite (Broadbent et al., 2014).

Claims of neglected evidence

You  express concern “relevant evidence” was neglected by the authors of the review.

You refer to 2 papers:

1: Cheng and Lynn (2013) and a study “(referred to by Cheng and Lynn).” However, you do not attempt to explain what this paper contributes. The journal (it is in Mankind Quarterly) is not one normally considered for publishing scientific papers and is extremely difficult to access. My reading of the paper indicates nothing new – in fact it is a repetition of the data from the Choi et al., (2012) paper (which I find strange as it doesn’t even cite that paper).

Why do you wish Mankind Quarterly to be cited? Published by the Ulster Institute for Social Research (and not a scientific body), Wikipedia describes it this way:

“It has been called a “cornerstone of the scientific racism establishment” and a “white supremacist journal”, “scientific racism’s keepers of the flame”, a journal with a “racist orientation” and an “infamous racist journal”, and “journal of ‘scientific racism’”.

2: The cross-sectional study by Saxena et al., (2012). I agree this wasn’t included – but then again it is not relevant to CWF. The study considered situations where drinking water F concentration was greater than 1.5 ppm.

Unfortunately the images you reproduce could give a misleading impression. The linear plot in your figure was actually for the relationship between urine F concentration and drinking water concentration.

The plot for intelligence grade does not look so impressive (see figure).


Saxena et al., (2012 ) do show an increase in mean intelligence grade (corresponding to a decrease in IQ) for the increasing concentration ranges. (You should perhaps note your reference to a standard deviation of 15 in such studies is clearly irrelevant to this study). They admit to several limitations in their study. We can agree with their assertion there is a “need for a more careful evaluation of the effect of fluoride on intelligence.” But given the endemic fluorosis in the area they studied, and in the areas of the studies reviewed by Choi et al., (2012) and studied by Choi et al., (2015) I suggest this is only relevant to such areas. I stress –  no such IQ differences were observed in areas where CWF is used (Broadbent et al., 2014).

I am aware of a number of other studies reporting cognitive deficits in areas of endemic fluorosis – suggesting IQ may well be a topical area of research in such areas. The NZ Fluoridation Review may not have cited these – precisely because they are not relevant to our situation.

However, I will reproduce some data from one of them (Sudhir et al., 2009) because it is directly relevant to the next topic. These authors did see increasing cognitive deficits with increasing concentration of F in drinking water. But they also saw a strong relationship between cognitive deficit and severe dental fluorosis (see figure below).


In this study IQ grade 5 is “intellectually impaired” and grade 3 is “intellectually average.”

Severe dental fluorosis and cognitive deficits

I stressed at the beginning of this letter that these IQ studies have all (except for Broadbent et al., 2014) concentrated on areas of endemic fluorosis. Children in these areas show high incidence of severe dental fluorosis and this is quite different to New Zealand (see the second figure in this letter). It is also noteworthy that Choi et al., (2015) chose to extend their work in an area of endemic fluorosis (in a Chinese village) and not an area of the USA where CWF is common. Maybe they recognise this is a problem for areas of endemic fluorosis and not for areas using CWF.

Unfortunately researchers like Choi et al., (2015) have limited their working hypothesis only to chemical toxicity. But, dental defects are known to cause decreased quality of life and this could be translated into learning difficulties and reduced IQ scores. In a recent article I suggested these researchers widen their considerations to including the hypothesis that severe dental fluorosis, in itself, could be a cause of cognitive deficits simply because of the effect of physical anomalies and appearance on IQ (see Perrott 2015).

This is, after all, consistent with their findings that cognitive deficits were significantly related to incidence of severe/medium dental fluorosis but not to the F concentration in the drinking water.

Other oral defects like bad dental decay are also known to cause a reduced quality of life and may lead to learning problems and cognitive deficits. While severe dental fluorosis is a problem in  areas of endemic fluorosis it is not here. I suggest you worry more about possible IQ effects of tooth decay than any due to fluoride in our drinking water.

You are just scaremongering with your flight of fancy suggesting that “institutionalizing the additional proportion of the population due to mental deficiency” should be considered as a cost against CWF. One could more sensibly say that in NZ the quality of life and possible cognitive deficits arising from dental decay should be considered as a cost against opposition to CWF.


Your letter is part of an ongoing campaign by New Zealand anti-fluoridation activists like FFNZ and New Health NZ to discredit the NZ Fluoridation Review. New Health NZ is part of the NZ Health Trust, a well-funded lobby group for the “natural”/alternative health industry in New Zealand. It campaigns on issues like fluoridation, vaccinations and “chemtrails” (see Who is funding anti-fluoridation High Court action? and Corporate backers of anti-fluoride movement lose in NZ High Court).

On the surface your complaint about the mistake in the summary of the NZ Fluoridation review is at least churlish. Especially as it was corrected when brought to the authors’ attention and there was no mistake in the body of the review. Despite the same mistake in the original version of Harvard University’s press release on the research neither you nor your colleagues in the NZ anti-fluoride movement have complained to Harvard University.

One would have though the correction of the mistake would have pulled the rug out from under the anti-fluoridation critics but you have unjustly tried to use the original mistake to argue that the authors of the NZ Fluoridation Review misunderstood or misrepresented the science. In fact, the misrepresentation comes from you and your anti-fluoridation colleagues as the study you seem to pin all your arguments on was made in areas of endemic fluorosis,  (mainly in China) and has no direct relevance to New Zealand CWF.

New Zealand health professionals and members of local bodies should see your complaint for what it is – part of the ongoing activist campaign against CWF. These decision makers are justified in the confidence they have in the NZ Fluoridation Review.

Yours sincerely,

Dr Ken Perrott


Beltrán-aguilar, E. D., & Barker, L. (2010). Prevalence and Severity of Dental Fluorosis in the United States , 1999 – 2004 (pp. 1999–2004).

Broadbent, J. M., Thomson, W. M., Ramrakha, S., Moffitt, T. E., Zeng, J., Foster Page, L. A., & Poulton, R. (2014). Community Water Fluoridation and Intelligence: Prospective Study in New Zealand. American Journal of Public Health, 105(1), 72–76.

Cheng, H., & Lynn, R. (2013). The adverse effect of fluoride on Children’s intelligence: A systematic review. Mankind Quarterly, 53, 306–347.

Choi, A. L., Sun, G., Zhang, Y., & Grandjean, P. (2012). Developmental fluoride neurotoxicity: A systematic review and meta-analysis. Environmental Health Perspectives, 120(10), 1362–1368.

Choi, A. L., Grandjean, P., Sun, G., & Zhang, Y. (2013). Developmental fluoride neurotoxicity: Choi et al. Respond. Environmental Health Perspectives, 121(3), A70.

Choi, A. L., Zhang, Y., Sun, G., Bellinger, D., Wang, K., Yang, X. J., … Grandjean, P. (2015). Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study. Neurotoxicology and Teratology, 47, 96–101.

Eason, C., & Elwood, JM. Seymour, Thomson, WM. Wilson, N. Prendergast, K. (2014). Health effects of water fluoridation : A review of the scientific evidence (p. 74).

Fluoride Free New Zealand. (2014). Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report

Hansen, L. (2015). An open letter to the Prime Minister’s Chief Science Advisor and to the President of the Royal Society of New Zealand.

Ministry of Health. (2010). Our Oral Health Key findings of the 2009 New Zealand Oral Health Survey. Wellington, Ministry of Health.

Perrott, K. W. (2015). Severe dental fluorosis and cognitive deficits. Neurotoxicology and Teratology.

Saxena, S., Sahay, A., & Goel, P. (2012). Effect of fluoride exposure on the intelligence of school children in Madhya Pradesh, India. Journal of Neurosciences in Rural Practice, 3(2), 144–9.

Sudhir, K. M., Chandu, G. N., Prashant, G. M., & Reddy, V. V. S. (2009). Effect of fluoride exposure on Intelligence Quotient ( IQ ) among 13-15 year old school children of known endemic area of fluorosis , Nalgonda District , Andhra Pradesh . JOURNAL OF THE INDIAN ASSOCIATION OF PUBLIC HEALTH DENTISTRY, 2009(13), 88–94.

Xiang, Q. (2014) Fluoride and IQ research in ChinaKeynote Address at FAN’s 5th Citizens’ Conference on Fluoride.






February ’15 – NZ blogs sitemeter ranking Ken Perrott Mar 02

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Image credit: Dear Kitty. Some blog

There are now over 300 blogs on the list, although I am weeding out those which are no longer active or have removed public access to sitemeters. (Let me know if I weed out yours by mistake, or get your stats wrong).

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters.

Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for February 2015. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers.

Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

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Rank Blog Visits/month Page Views/month
1 Whale oil beef hooked 1697269 2947932
2 Kiwiblog 299472 541919
3 The Standard 189833 417128
4 Transport Blog 163834 167986
5 The Daily Blog 121994 205870
6 Liturgy 52714 80408
7 The Dim-Post 38573 53528
8 Sciblogs 33609 42552
9 Music of sound 16603 21379
10 No Minister 15436 20150
11 No Right Turn 14792 19120
12 Liberation 14761 20903
13 The REAL Steve Gray 14612 20564
14 Homepaddock 14327 22515
15 Stats Chat 13930 22019
16 Offsetting Behaviour 12073 18313
17 Save our Schools NZ 11552 13752
18 Fields of Blood 11271 16746
19 Throng New Zealand 10888 19301
20 Tikorangi: The Jury Garden 9277 11816
21 Right Reason 8608 11774
22 MandM 8449 9346
23 Open Parachute 8169 10603
24 Matte Shot 7223 8984
25 Bill Bennett 6817 8584
26 Talking Auckland 6792 8742
27 Chris no-frills 6668 8280
28 Imperator Fish 6412 8525
29 Hot Topic 6207 8228
30 Aotearoa: A wider perspective 6025 7614
31 Cycling in Christchurch 5207 7072
32 Anglican down under 5026 6884
33 Lindsay Mitchell 4940 6189
34 Capitalism is bad 4736 514
35 Mousehouse 4639 7608
36 Teaching the Teacher 4536 6136
37 Autism & Oughtisms 4456 4514
38 Lance Wiggs 4355 5148
39 Reading the maps 3826 4775
40 In the back of the net 3540 5016
41 Quote Unquote 3113 3387
42 Home education Foundation 3044 4720
43 OracleNZ by Francisco Munoz Alvarez 3011 3303
44 Super Rugby Tips 2888 3695
45 Vomkrieg 2651 4406
46 Otagosh 2640 4919
47 Kiwi Cakes 2451 3489
48 Scepticon 2398 2671
49 Waiology 2369 2900
50 Windy Hilltops 2317 3602
51 Rodney’s Aviation Ramblings 2248 3004
52 New Zealand Conservative 2145 2562
53 AmeriNZ 2070 2339
54 Crime Watch 2064 2986
55 The Woolshed Wargamer 1920 3300
56 Scotty Donaldson 1891 2631
57 On the Left 1859 2581
58 Sustain:if:able Kiwi 1774 2762
59 Open Parachute @ SciBlogs 1680 1883
60 Canterbury Atheists 1587 1783
61 Pdubyah – a life just as ordinary 1573 2151
62 Woodleigh Nursery 1463 3048
63 A conservative perspective 1459 2055
64 Eye on the ICR 1367 1702
65 Works in progress 1342 2132
66 Wysiwygpurple’s Blog 1119 1603
67 Off the couch 1118 1658
68 Code for Life 1114 1259
69 Episto 1106 1364
70 ICT Teaching and Learning  1092 1561
71 Put ‘em all on an island 1082 1411
72 Four seasons in one 1047 1212
73 The Meaning of Trees 1046 1270
74 james lin’s blog 1041 1057
75 Michael Jeans 1005 1376
76 Two Minutes Sport 990 1145
77 A Bee of a Certain Age 969 1094
78 Socialist Aotearoa 963 1108
79 Stratford Aerodrome 929 1246
80 Blessed Economist 926 1153
81 Social Media & the 2014 Election 925 1224
82 Life Behind the IRon Drape 924 2360
83 PM of NZ 908 1056
84 869 943
85 Man of Errors 858 951
86 misc.ience @ Sciblogs 857 926
87 Notes from the bartender 851 958
88 Anne Free Spirit 840 1290
89 Life is not a race to be finished first 817 1210
90 Keeping Stock 780 964
91 One Furious Llama 754 1067
92 Derek’s blog 748 1150
93 Show your workings 664 907
94 Brad Heap 631 773
95 From the Earth’s End 622 861
96 Einstein Music Journal# 580 735
97 Brennan McDonald 559 661
98 Ideologically impure 547 622
99 Room 5 @ Melville Intermediate School 540 690
99 Room One @ Auroa School 540 1500
101 Science in a van 536 708
102 SmallTorque 504 767
103 Goings on at the Madbush Farm 502 632
104 Hitting Metal With A Hammer 497 598
105 Stitchbird 484 807
106 Taradale Blog# 480 990
107 Kidney Punch  457 520
108 goNZo Freakpower Brains Trust 444 464
109 Riddled 440 661
109 Polit Ecol 440 486
109 A communist at large 440 486
112 Tauranga Blog 434 483
113 Skeptiocon @ Sciblogs 429 479
114 Tararua District Library 427 540
115 Bob McKerrow – Wayfarer 421 557
116 AnneKcam
420 870
117 The IT Countrey Justice 411 538
118 Dad4justice 409 441
119 Creative Voice# 390 750
119 Family integrity 390 441
121 Quietly in the backgroud 386 517
122 True Paradigm 376 519
123 Software development and stuff 367 418
124 Tales from a Caffeinated Weka 360 672
124 Kutarere’s Blog  360 439
126 Perissodactyla 359 421
127 Exile in New zealand 350 413
128 Halfdone 347 419
129 sticK 342 394
130 Media Sport and Other Rantings 337 377
131 My thinks 327 350
132 Webweaver’s world 317 381
133 Glenview 9 303 326
134 Glennis’s Blog Page# 300 390
135 roarprawn 285 441
136 Jo Blogs 280 460
137 Spatula Forum 279 305
138 Artichoke 266 321
139 kiwiincanberra 246 270
139 Wokarella 246 270
141 eyeCONTACT 241 296
142 Nelsonian’s life 240 300
143 ElephaNZa  236 236
144 Samuel Dennis 225 234
145 Get Out Gertrude! 223 356
146 Unity Blog 213 227
147 Pointless and adsurb 212 303
148 Aphrodite rises 207 257
149 Springston School Library Blog 201 288
150 Cut your hair 198 199
151 This Mum Rocks 195 227
152 Toni Twiss 194 194
153 The Gentically Insane 189 244
153 The Genetically Insane 189 244
155 ZNO 188 242
156 The Little Waaagh! That Could 181 222
157 The Fundy Post 180 253
157 Manaia Kindergarten 180 270
159 $100 Dialysis 177 208
160 MartinIsti Blog 175 226
161 Grumpollie 171 198
162 Ruggerblogger 169 220
163 Upstage 168 246
164 Prior Knowledge  166 185
164 166 185
166 Rest Area 300m 162 197
167 kiwi simplexity 159 180
168 Canvassing for opinion 156 183
169 Cimba7200’s thoughts 150 180
169 King’s High School Library 150 180
169 Mountains of Our Minds# 150 180
172 High voltage learning during the Christchurch earthquakes 126 193
173 Dragonsinger 124 141
174 Korero Pt England 120 210
175 NZ First Youth 119 147
176 UpsideBackwards 106 115
177 Sharlene says 104 161
177 The Well read Kitty 104 106
179 Lost Soul 99 106
180 jo russ photo diary 97 197
181 Fuller’s watch# 91 118
182 Virtual North 90 150
182 Making IT Happen 90 120
182 John Macilree’s Weblog# 90 120
185 White & Black 89 110
186 Sam Books and Thoughts 87 130
187 Creative Collision 82 83
188 At home with Rose 81 90
188 Carolyn’s blog 81 96
190 Journey to a mini me 75 97
190 John Macilree’s Blog 75 82
192 global village governance 72 129
193 Discovery Time 71 102
194 Millenium X 67 96
195 Shelly van Soest Artist 63 72
196 The Catalyst 60 90
196 Pt England Scribes 60 60
196 Digital learning 60 90
196 Sleeping with books 60 60
196 Moving the crowd 60 60
196 Social Policy Bonds Blog 60 75
196 Room 24, 2012 60 90
196 James McKerrow – Surveyor 1834-1919# 60 90
196 The Official Ebenezer Teichelmann Blog# 60 90
205 New Zealand Indian Fine Arts Society 58 71
206 Politicalisation 57 63
206 TVHE 57 63
208 Something Interesting to read 52 59
208 Looking in the square 52 61
208 Ellie Great 52 62
208 University of Otago, Law Library Blog 52 73
212 Nathanael Baker 48 56
213 Frontlawn 43 53
214 You’re Underthinking 41 43
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Paper claiming water fluoridation linked to hypothyroidism slammed by experts Ken Perrott Feb 25

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“As epidemiological evidence goes, this is about as weak as it gets.”

Author Stephen Peckham – former chairperson of activist group “Hampshire against fluoridation”

That is the comment by Prof David Coggon, Professor of Occupational and Environmental Medicine, University of Southampton, on a new paper claiming hyporthyroidism is linked to water fluoridation. Published yesterday in the peer-reviewed Journal of Epidemiology & Community Health, the paper is:

Peckham, S., Lowery, D., & Spencer, S. (2015). Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water. J Epidemiol Community Health, 1–6.

Prof Coggan goes on to say:

“Essentially the researchers have shown that after limited adjustment for demographic differences, there are somewhat higher rates of hypothyroidism (which can result from a number of different diseases) in four areas of England that have higher concentrations of fluoride in drinking water.   It is quite possible that the observed association is a consequence of other ways in which the areas with higher fluoride differ from the rest of the country.  There are substantially more rigorous epidemiological methods by which the research team could have tested their idea”

Having read the paper I think that about sums it up.

Critical role of iodine.

The authors acknowledge that iodine plays a key role in thyroid status but they did nothing to include dietary intake or deficiency in their statistical model. It is just not good enough to declare “it is unlikely that there are significant differences [in dietary iodine intake] between people, living in fluoridated and non-fluoridated areas.”

They did include data for the proportion of people over 40 and the proportion of females because they recognised age and gender influence the incidence of hyperthyroidism. So why not include dietary iodine which is recognised as the main factor? And they are arguing that fluoride potentially acts as an iodine inhibitor, making the data for iodine even more important. Perhaps this data was not so easy to find – but did they look very hard?

Correlation is not causation

This cannot be repeated often enough. Trouble is that almost anyone can get hold of data these days and force it through a statistical package. And if they have a bias to confirm, and are willing to select their data and avoid confounders, they might get lucky.

This seems to be the case here as the senior author is a well-known anti-fluoride campaigner in the UK.* This is outside his specialty (health policy, not epidemiology).

Fluoridation data is readily available for cities and regions but it can easily be a proxy for more meaningful information like the size of towns (smaller towns usually don’t have artificially fluoridated water) or rural/urban distinctions. Cultural and ethnic factors may also be reflected in fluoridation data.

In this case, Peckham et al., (2015) simply correlated the incidence of hypothyroidism reported by individual medical practices against drinking water fluoride concentrations reported by local bodies in the region. There was no attempt to match data at the individual level. And there was no attempt to include dietary iodine intake as a factor – despite its key importance.

The size of the effect

The prevalence of hypothyroidism in the data they used is relatively low  – 3.2% with a standard deviation of 1.1%. The authors argue their results would mean that fluoridation would increase this small number by a small amount (about 30%).

Given the tentative nature and unreliability of their conclusions – if only because they did not consider dietary iodine as a factor – their recommendation should be taken with a grain of salt (preferably iodised). They recommend:

“To minimise the risk of increasing the prevalence of hypothyroidism, it is important, therefore, to limit fluoride ingestion from all sources.”

Sensible health authorities will balance the low incidence of hypothyroidism and the small effect Peckham et al (2015) claim, based on their unsatisfactory analyses, against the fact of the beneficial role that fluoride plays in the oral health of most people throughout their lives

Obviously authorities are no going to change their views as a result of this paper. Of course there will be special pleading by those opposed to fluoridation. They will argue that despite the problems with this paper the questions of fluoride as a factor in hyperthyroidism should be research further. Of course it should – scientific conclusions are always open to being altered by new evidence. But future research must be of a better quality than this. As a Prof Coggan says:

“There are substantially more rigorous epidemiological methods by which the research team could have tested their idea”

Stephen Peckham is a well-known anti-fluoride activist

I discussed Stephen Peckham in a earlier article Peer review, shonky journals and misrepresenting fluoride science. This deals with a previous paper of his and the journal he published it in.

That paper was a collection of the usual anti-fluoride arguments – based in citations without any original work. It was published in a shonky journal known to have poor peer review standards.

The current paper is in a reputable journal and does include some original work – although it is basically a statistical analysis of readily available data. No effort seems to have been made to include data for dietary iodine intake which I would think is a basic need for such a study. I am personally surprised the reviewers used by this journal did not seriously question the paper’s publication for that reason alone. I guess this reflects the imperfect and human nature of peer review even in good science journals.

At least with the current paper Stephen Peckham has declared  a conflict of interest involving his activity opposing water fluoridation – this did not happen with his earlier paper.

I expect this new paper will become another weapon in the anti-fluoridation artist armoury. It will be cited and presented as absolute proof that fluoridation is bad for our thyroids. Claims will be made that a leading scientific journal and university officially claim this! Harvard University and The Lancet all over again.

But sensible readers should never take such claims at face value. Just because a paper is published in a reputable peer-reviewed journal does not make it gospel truth. Whatever the source, such papers need to be considered intelligently and critically.

This paper does not live up to the claims the anti-fluoride propagandists will make about it.

See also:

Flawed study overstates link between fluoride and ill health: experts
Tournage de la scène «Fluoration de l’eau», prise 2793… (Shooting the scene “Water fluoridation,” taken in 2793)

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NZ Fluoridation review – Response to Micklen Ken Perrott Feb 18

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I welcome open and transparent discussion here so am thankful to Dr Micklen for his response (see NZ Fluoridation review – HS Micklen responds to critique). Unfortunately he is the only author or “peer-reviewer” of Fluoride Free NZ’s report criticising the NZ Fluoridation review to accept my offer of a right of reply to my critiques.

A pity, as if any of them think I have got things wrong, and they can support this with evidence, I certainly want to know about it.

There are three aspects to Dr Micklen’s reply – dental fluorsis chronic kidney disease and his critique of my letter in the journal Neurotoxicology and Teratology –   Perrott (2015). I will deal with these separately.

Dental fluorosis

I appreciate Dr Micklen is unhappy about my criticisms of his article, and my suggestion his comments of dental fluorosis were muddled. I may have been a bit harsh but he has still not responded to my specific criticism that he:

“unfairly attributes the more severe forms [of dental fluorosis] to community water fluoridation (CWF). Consequently he calculates a cost of dental treatment which is wrong.”

The key problem is that Micklen is assuming that all the  medium and severe dental fluorosis can be attributed to CWF, whereas none of it can.

Briefly reviewing the argument – the figure below is from the NZ Ministry of Health’s Our Oral Health – the same source Micklen used.

My comment on the relevance of the different grades of dental fluorosis was:

“Moderate and severe grades of dental fluorosis are common in areas where fluorosis is endemic, but relatively rare where CWF is used. Occurrences in the latter case, despite the low concentrations of fluoride in treated drinking water, will have other causes – high natural levels in well water, industrial pollution, excessive consumption of toothpaste, etc.”

The important factor is that severe and moderate forms of dental fluorosis are not caused by CWF.

CWF can contribute to mild and very mild forms of dental fluorosis but because these are usually judged positively they certainly don’t need expensive veneers – my dentist colleagues advise simple microabrasion usually works.

So Micklen was wrong to suggest the cost of cost of veneers (up to $1750 per tooth) should be attributed to CWF because such costs would be encountered in non-fluoridated areas as well.

(In fact, if Micklen had calculated costs for such treatment in non-fluoridated areas using the “Oral Health” data in the literal way he did for the fluoridated areas,  he would have found costs to be higher than in non-fluoridated areas! Certainly doesnt’ support his claim but a meaningless result because of the small numbers and large variability).

Chronic kidney disease

Micklen accuses me of  using “a piece of grammatical legerdemain to pretend that I [Micklen] called for CKD sufferers to be warned to avoid tap water, which I did not.”

Granted he left himself a way out by actually writing:

“I suspect that most opponents of fluoridation would call for CKD sufferers to be warned to avoid tap water. Possibly the NZ health authorities have done so.”

OK, so its not a direct personal recommendation (perhaps he doesn’t belong to the group of “most opponents of fluoridation”) but a reader could be excused for getting that message and in this context it comes across as “dog whistling.”

However I will accept his assurance now that:

” In fact, I am inclined to agree with him [me] that that might be extreme in the present state of knowledge.”

As for questions like: “Does further research on the topic receive any funding priority, for example?” – well this is a round about way of giving the message that it doesn’t. Perhaps he should actually check that out and give some evidence instead of making an unwarranted implication.

This tactic of posing unfounded questions to convey an unwarranted message is typical of the approach Micklen and Connett take in their book The Case against Fluoride. I criticised this tactic in my exchange with Paul Connett (see Fluoride Debate).

I reject Micklen’s suggestion that:

“Perhaps it would be embarrassing, too, for a government to insist on putting fluoride in the water and then advise a substantial number of people not to drink it – or so one might think.”

That is silly – it is like a conspiracy theory. Why would genuine health authorities refuse to give warnings to a small group of people who might be put at risk from a social health policy that is beneficial to the vast majority? Surely they are used to such situations.

I also think he is waxing lyrical with the word “substantial!” The numbers involved would be very small, if any, and such a group would already be advised about a number of risks to them because of their condition and treatments.

Micklen also lets his ideological position take over  by drawing the implication from my article that I am saying CWF is “effective and safe – for some.” Far from it. Surely I am saying it is effective and safe for the vast majority (which is what we can expect from a social health policy) and simply recommending (as in all such policies) that the small group of people, if any, who might be at risk should use alternatives.

I am actually saying that CWF is effective and safe for at least  the vast majority and that claims to the contrary should be backed up with evidence which should be considered critically

Severe dental fluorosis and cognitive deficits

I thank Dr Micklen for his comments on my letter in the journal Neurotoxicology and Teratology – (Perrott 2015). I am pleased he accepts the hypothesis that severe dental fluorosis could explain observations of cognitive deficits is worth considering and  he agreed with the other reviewers the letter was worth publishing.

Influence of age

I take his point that the poor appearance of teeth may not influence young children (ages 6-8 as in the small the group Choi et al, (2015) studied). However, this is pure speculation on his part and is surely a detail. A detail that should be considered in any planned research incorporating this hypothesis, but not in itself a reason for rejecting the hypothesis out of hand – surely?

Unless, of course, he can give evidence to support his suggestion. I notice that he does not support the idea with any citations so suspect the idea is more one of straw-clutching  than a serious suggestion.

Actually most, but not all, of the citation I used did indeed refer to work with older children. Some were review papers and did not limit their review to any age group. Aguilar-Díaz, et al., (2011) considered children from 8 – 10 years old, Do and Spencer, (2007) studied 8-12 year olds and Abanto et al., (2012) 6-14 year old children. Chikte (2001) studied three groups: 6, 12, 15 year olds.

However, I found a quick literature search showed reports of negative effects of oral defects like tooth decay on the child’s quality of life. Kramer et al., (2013) reported this for ages 2 – 5, Scarpelli et al., (2013) for 5 year olds and Cunnion et al., (2010) for 2 – 8 year olds.

So, I suggest on the available evidence the negative influence of severe dental fluorosis on quality of life (and possibly cognitive deficits) is likely to occur even in younger children who have not “reached an age to be self-conscious about their appearance.”

I don’t think young children are as immune to social attitudes and personal appearance as Dr Micklen suggests.

Does effect depend on how common dental fluorosis is? 

Dr Micklen suggests that:

“Since fluorosis was common in the community [the children studied by Choi el., 2015], having the condition would not appear abnormal.”

Again I think he is indulging in straw-clutching, or special pleading.


Clearly medium and severe dental fluorosis is far more common in this Chinese group than in countries like New Zealand which use CWF. In the graph below I compare their data with that for New Zealand and USA. Incidentally, this figure shows why the data from Choi et al., (2012, 2015) should not be used as an argument against CWF – yet that is what Micklen did in his original article.


But this does not mean that those children with more severe forms will not stand out against the children with less severe forms. There is always a range of appearances of such defects in a group of children. Some will obviously suffer more than others because of their appearance.

If Choi et al., do continue to include detailed analysis of dental fluorosis in their future work on this issue then it will be possible to compare cognitive deficit measurements with dental fluorosis indices in a larger group. Such data will be interesting.

However, discussion of details like this is premature. My letter simply raised to idea as an alternative worth considering and encouraged the group to continue including detailed dental fluorosis measurements in future work. I was also concerned that they were not being sufficiently open-minded in their choice of a working hypothesis. I concluded my letter with:

Researchers need to be careful not to limit their possible hypotheses or research approaches. Unfortunately Choi et al. (2014) appear to be doing just this with their plans for a larger scale study targeted only at “fluoride’s developmental neurotoxicity.”

Unfortunately none of this group have yet responded to my letter.

So, again, I thank Dr Micklen for his feedback on that letter – and his acceptance of the right-of-reply to my article critiquing the FFNZ report.

See also:


Abanto, J., Carvalho, T. S., Bönecker, M., Ortega, A. O., Ciamponi, A. L., & Raggio, D. P. (2012). Parental reports of the oral health-related quality of life of children with cerebral palsy. BMC Oral Health, 12, 15. doi:10.1186/1472-6831-12-15

Aguilar-Díaz, F. C., Irigoyen-Camacho, M. E., & Borges-Yáñez, S. A. (2011). Oral-health-related quality of life in schoolchildren in an endemic fluorosis area of Mexico. Quality of Life Research : An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation, 20(10), 1699–706.

Chikte, U. M., Louw, A. J., & Stander, I. (2001). Perceptions of fluorosis in northern Cape communities. SADJ : Journal of the South African Dental Association = Tydskrif van Die Suid-Afrikaanse Tandheelkundige Vereniging, 56(11), 528–32.

Choi, A. L., Sun, G., Zhang, Y., & Grandjean, P. (2012). Developmental fluoride neurotoxicity: A systematic review and meta-analysis. Environmental Health Perspectives, 120(10), 1362–1368.

Choi, A. L., Zhang, Y., Sun, G., Bellinger, D., Wang, K., Yang, X. J., … Grandjean, P. (2015). Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study. Neurotoxicology and Teratology, 47, 96–101.

Cunnion, D. T., Spiro, A., Jones, J. a, Rich, S. E., Papageorgiou, C. P., Tate, A., … Garcia, R. I. (2010). Pediatric oral health-related quality of life improvement after treatment of early childhood caries: a prospective multisite study. Journal of Dentistry for Children, 77, 4–11.

Do, L. G., & Spencer, A. (2007). Oral Health-Related Quality of Life of Children by Dental Caries and Fluorosis Experience. Journal of Public Health Dentistry, 67(3), 132–139.

Kramer, P. F., Feldens, C. A., Ferreira, S. H., Bervian, J., Rodrigues, P. H., & Peres, M. A. (2013). Exploring the impact of oral diseases and disorders on quality of life of preschool children. Community Dentistry and Oral Epidemiology, 41(4), 327–35.

NZ Ministry of Health. (2010). Our Oral Health Key findings of the 2009 New Zealand Oral Health Survey.

Perrott, K. W. (2015). Severe dental fluorosis and cognitive deficits. Neurotoxicology and Teratology.

Scarpelli, A. C., Paiva, S. M., Viegas, C. M., Carvalho, A. C., Ferreira, F. M., & Pordeus, I. A. (2013). Oral health-related quality of life among Brazilian preschool children. Community Dentistry and Oral Epidemiology, 41(4), 336–44.

NZ Fluoridation review – HS Micklen responds to critique Ken Perrott Feb 17

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I have posted several articles in a series critiquing contributions to the Fluoride Free NZ report Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report which is aimed at discrediting the recent review Health Effects of Water Fluoridation: a Review of the Scientific Evidence produced by the Royal Society of NZ together with the Office of the Prime Minister’s Chief Science Advisor. The articles in this series are collected into a pdf document which can be downloads from Download report analysing anti-fluoride attacks on NZ Fluoridation Review.

In an attempt to encourage a discussion on the fluoridation review and the FFNZ report I offered all the authors and “peer-reviewers” of the FFNZ report the right of reply to my critiques. So far Dr H. S. Micklen (whose article I critiqued in Fluoride Free NZ report disingenuous – conclusion), is the only one to take up this offer.

Here is his reply. 

I thank Dr Perrott for reproducing my notes on the NZ Fluoridation Review and appreciate his comments. My appreciation would be warmer had he spent less time using his imagination and paid more attention to what I actually wrote.  He has me bustling around, agenda in hand, clutching at straws here, raising bogeys there, scaremongering, relying on this, calling for that, and getting confused about different grades of fluorosis (as if..,). All nonsense.  If I “distort the science” as Perrott’s headline proclaims, he does a great job of distorting the distortion.

Most of my short piece merely commented on a few places where, in my opinion, the NZ report failed – through error, omission or incompetence – to reach proper standards of objectivity and impartiality and exhibited ill-founded complacency. Since the NZ report was highly biased in favour of fluoridation, any criticisms of it are likely to have an anti-F flavour. Too bad; I was dealing with the report’s view of the science, not pushing my own. I avoided speculating on the outcome of issues that I consider unresolved, dental fluorosis (where Perrott makes nonsense of what I wrote) being the only exception.

Most of these issues have been argued over ad nauseam and I shall not try to unscramble Perrott’s lucubrations. The question of chronic kidney disease and its possible cardiovascular consequences is perhaps an exception. I gave credit to the Review for discussing the paper by Martin-Pardillos. Agreeing with the Review’s opinion that the results needed to be confirmed, I remarked “The interesting question is, what should happen meanwhile?” That is not a rhetorical question. What does, or should, happen when an alarm bell sounds over a long-established procedure? Does further research on the topic receive any funding priority, for example?  Perrott uses a piece of grammatical legerdemain to pretend that I called for CKD sufferers to be warned to avoid tap water, which I did not. In fact, I am inclined to agree with him that that might be extreme in the present state of knowledge. Perhaps it would be embarrassing, too, for a government to insist on putting fluoride in the water and then advise a substantial number of people not to drink it – or so one might think. But Perrott concludes “Any patients who are particularly worried can then take steps like using filtered water for their own peace of mind. This seems more appropriate than denying the rest of the population access to a simple, effective and safe (for them at least) social health policy like CWF.”  So that’s all right then, thanks to the patients, whom Perrott doubtless consulted, being willing to promote the alleged greater good. He has pricked a hole in the old mantra, though: “effective and safe – for some”.

Perrott asked for my feedback on his idea about the possible effect of dental fluorosis on IQ.  Since then his paper has appeared online as a short article in Neurotoxicology and Teratology. Perhaps the best thing I can do at this stage is pretend that it had arrived on my desk for peer review. I would have commented as follows.

“This communication refers to a recent paper by Choi et al (2014) that reports certain cognitive defects in young children affected by moderate-severe dental fluorosis. Choi et al suggest that this is due to an adverse effect of fluoride on the developing brain. The present author proposes an alternative explanation, namely that fluorosis itself, and the stress of living with it, can affect learning and general quality of life and result in poor performance in certain types of cognitive test. This appears to be a novel idea and, as such, is suitable in principle for publication as a short communication. There is, however, a fundamental question that the author should be invited to address and clarify with a view to possible resubmission.

“The paper is somewhat discursive and lacking in focus and in the course of it the author seems to lose track of what age group he is talking about. Surprisingly, he does not mention the age of Choi’s (2014) subjects, which averaged 7 years  (range 6-8). When he finally presents evidence that moderate-severe fluorosis is aesthetically displeasing and likely to impair quality of life, all of it relates to older children, mainly teenagers, who have reached an age to be self-conscious about their appearance and have been living with fluorosis for several years. In contrast, 16% of Choi’s (2014) subjects had no erupted permanent teeth at all and in the remainder eruption of the first permanent teeth would have been very recent. Since fluorosis was common in the community, having the condition would not appear abnormal. The crucial question is whether the author is proposing that the quality of life of these young children is so compromised by fluorosis as to impair their performance in cognitive tests. Apparently the answer is a tentative affirmative: It is just possible that the negative quality of life associated with oral defects like severe dental fluorosis contribute to cognitive deficits reported by Choi et al. (2012, 2014)’

“The author needs to discuss this issue in a transparent fashion so that readers can judge for themselves whether the proposal is plausible. Conversely, if he is not making such a proposal, that too should be made clear.

“The author might wish to refresh his memory of the paper by Hilsheimer and Kurko (1979), which really is of virtually no relevance to his argument.”

I hope this helps.

H S M 12 February 2015

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Did business interests interfere with Hamilton’s fluoride tribunal process? Ken Perrott Feb 15

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 Source: Abuse of democratic process in Hamilton Tribunal?. (Click to enlarge).

Early results from a Waikato University research project show that around 2/3 of all the written submissions to the Hamilton City Council’s fluoride tribunal process were directly or indirectly provided by parties associated with the ‘natural health’ lobby.

This is interesting as it raises the question of links between this lobby and the anti-fluoride movement. I showed in When politicians and bureaucrats decide the science  how the submission process in this case was dominated by the anti-fluoride movement and how their misrepresentation of the science fooled the local body politicians and bureaucrats. In Who is funding anti-fluoridation High Court action? I showed how big money from the “natural” health industry was financing legal action against fluoridation.

This research is not yet complete so we look forward to further details on this relationship and on how such corporate interests and activists groups cooperate in submissions to local body councils.

The research project is “Public Integrity and Participatory Democracy: Hamilton City Council’s Water Fluoridation Decision“. Waikato University student Luke Oldfield is carrying out the work financed by the grant. He recently displayed a poster(above) to an audience of academic faculty sharing some preliminary results of his research.

Interestingly spokespeople for the anti-fluoride groups have opposed this research from the moment of the announcment of the grant (see Anti-fluoride activists unhappy about scientific research).

Something to hide, perhaps?

Thanks to Abuse of democratic process in Hamilton Tribunal? at the new Making Sense of Fluoride web page.

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A perspective of distances in space Ken Perrott Feb 11

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This video has been making the rounds lately. It is a view of the sun, the camera moving back at the speed of light – illustrating in realtime, the journey of a photon of light emitted from the surface of the sun and traveling across a portion of the solar system – from a human perspective.

The animation ends at Jupiter Even so, it certainly illustrated to me that interplanetary travel is going to get extremely boring without lots of things to occupy the travellers. They won’t be travelling this fast.

Riding Light on Vimeo

Credit: Thanks to RT: Seeing stars: Traverse Solar System at speed of light

Phil Plait gave another perspective of distances in space in his article Can You Really Fit All the Planets Between the Earth and Moon?

He answers the question with a Yes – sometimes!


At most times the planets just do not fit.


At apogee, when the Moon is farthest from the Earth, the center-to-center distance is more like 406,000 km, so about 398,000 km surface-to-surface. Aha!

At lunar apogee, the planets do fit, rather comfortably. And there’s more: I used the average diameters of the planets. Most of the planets are not spherical, but due to their rotation they’re oblate, or squashed; smaller in diameter through their poles than across their equators. We can make them fit better if we align them through their polar axes. That total distance is 364,799 km. That’s still too much if the Moon is at perigee, but gives us a little more breathing room when the Moon’s at apogee.

Finally, we can look at the average distance of the Earth to the Moon, which is 384,400 km, or 376,000 km surface-to-surface. In that case the planets fit if we align them pole to pole, but not using their average diameters.

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Download report analysing anti-fluoride attacks on NZ Fluoridation Review Ken Perrott Feb 09

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The NZ Fluoridation review, Health Effects of Water Fluoridation: a Review of the Scientific Evidence, is an authoritative and up-to-date review on water fluoridation in New Zealand. The anti-fluoridation activist organisation Fluoride Free NZ (FFNZ) attempted to discredit the review with their report Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report.

In this report, Fluoridation is Safe and Effective, I analyse the FFNZ critique and show it was written, and “peer-reviewed” by well know anti-fluoridation activists

This report analyses the three main articles in the FFNZ document showing that the critique is based on misinformation commonly promoted by anti-fluoride propagandists.

I point out a small mistake in the executive summary of the Fluoridation review and describe how it arose. The concept was explained correctly in the body of that report. The mistake, little more than a typo, has now been corrected.

Fluoridation is Safe and Effective is a slightly edited version of a number of articles posted on this blog. It is now available to download in pdf format.

I hope this report will be useful wherever Fluoride Free NZ use their own document in an attempt to discredit the NZ Fluoridation Review. If FFNZ use their misleading document in their campaigns to local body councils, or in presentations to the media and public meetings this report can provide the material which debunks their claims.

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Social health policies, freedom of choice and responsibility Ken Perrott Feb 05

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Social health policies inevitably raise the issue of the individual’s freedom of choice. While debates around these policies often concentrate on questions of fact, scientific consensus and reliability of evidence, these tend to be surrogates for the underlying values issues. To what extent should I sacrifice my freedom of choice, or my freedom of choice to decide for my children, for the good health of the community? And what if my freedom of choice violates the freedom of choice for others?

hall-offit-fullPaul Offit discussed these issues in a recent Point of Inquiry podcast – Paul Offit, MD, on Measles in the Magic Kingdom and the Anti-Vaccine Movement. He is a Professor in the Division of Infectious Diseases and the Director of the Vaccine Education Center at the Children Hospital of Philadelphia. Offit is the author of the book Do You Believe in Magic?: The Sense and Nonsense of Alternative Medicine.

He basically talks about the spread of measles throughout California and neighboring states because of a source of infection at Disneyland. Although measles were eliminated in the U.S. by 2000, the misinformation of the anti-vaccine movement has caused a return of a full-fledged outbreak.

Levels of responsibility and consequences

Paul makes the comparison of opposition to vaccination with opposition to blood transfusion.

1: Blood transfusions. A person my refuse to accept treatment involving blood transfusion because of their personal religious beliefs. More questionably they may refuse on behalf of their children. However, the consequences are limited to the person or her child. The decision does not harm the community at large.

2: Vaccinations. A person may refuse a measles vaccination for themselves or their children. But in this case the consequences are not personal – they affect the whole of society. By lowering the degree of immunisation in the community they threaten the lives of others – particularly the most vulnerable, children.

In these two cases the person has refused an intervention, a medical treatment or vaccination, which could be seen to violate their freedom of choice – or even to violate their body. In the first case the consequences are personal, limited to the person who made the wrong decision. But in the second case the consequences are social. An personal wrong decision has taken away the freedom of choice, the health and in some cases the lives, of others in society.

A bit like the personal decision to drive on the wrong side of the road. Society has taken away a small personal freedom of choice in our road rules to protect the lives of all of us.

3: Fluoridation. Social health policies like community fluoridation of water, salt, milk, etc., are recognised as being safe, beneficial and cost-effective. But they are opposed by a vocal minority. Activists will passionately promote the freedom of choice argument and, considering they don’t have the scientific evidence on their side this is often seen as their strongest argument. After all, it is values-based and therefore can’t be tested and rejected by evidence.

But, this third case is different to the other 2.

  • The act of fluoridation or not is social, taken by society as a whole or their representatives. An person may contribute to the decision but cannot decide the issue by a personal action as they can with vaccinations or blood transfusions. Although individual political action, or dissemination of information or misinformation, may influence that social decision – and hence the social consequences.
  • Fluoridation does not involve an intervention or treatment, medical or otherwise. No one is forced to drink fluoridated water or milk, or to consume fluoridated salt. The freedom of choice argument is invalid here because there are always alternatives.

Despite actively promoting the freedom of choice argument even the NZ anti-fluoride activist Fluoride Free NZ provides information on these atlernatives. They list alternative water sources, distillation, ion exchange filters and reverse osmosis. Most of these choices are cheap and available.

So what is driving anti-fluoridation propagandists?

Unlike opponents to blood transfusion they cannot argue freedom of choice to refuse an intervention on religious grounds. There is no intervention. The only personal imposition is that they may wish to buy a water filter (many already have these) or buy water from a different source.

Again, unlike opponents of vaccination they cannot argue freedom of choice to refuse an intervention even on grounds of personal belief – because there is no personal intervention.

Given the lack of any forced or personal intervention I am forced to conclude the freedom of choice issue that concerns the anti-fluoride activists is their freedom of choice to decide the oral health quality of other members of their community. And given the health and scientific expert consensus on the issue they are really arguing for their freedom of choice to decide the oral health of others on the grounds of their own minority personal beliefs or convictions.

In last year’s High Court judgement on the question of fluoridation in South Tarinaki, Justice Hansen wrote:

“Provided it does not have consequences for public health a person has the right to make even the poorest decisions in respect of their own health. But where the state, either directly or through local government, employs public health interventions, the right is not engaged. Were it otherwise, the individual’s right to refuse would become the individual’s right to decide outcomes for others. It would give any person a right of veto over public health measures which it is not only the right but often the responsibility of local authorities to deliver.”

The freedom of choice the anti-fluoride activists are promoting is their freedom of choice to decide health outcomes for others – not themselves.

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January ’15 – NZ blogs sitemeter ranking Ken Perrott Feb 01

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Credit: 10 Social Media Facts, Figures and Statistics You Need to Know

There are now over 300 blogs on the list, although I am weeding out those which are no longer active or have removed public access to sitemeters. (Let me know if I weed out yours by mistake, or get your stats wrong).

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters.

Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for January 2015. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers.

Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

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Rank Blog Visits/month Page Views/month
1 Whale oil beef hooked 1549207 2771035
2 Kiwiblog 232512 447489
3 The Standard 163164 356129
4 Transport Blog 138388 141978
5 The Daily Blog 116155 188868
6 Liturgy 62950 95232
7 NewZeal 47047 56964
8 Sciblogs 36167 45702
9 The Dim-Post 27970 40038
10 No Minister 16256 21751
11 Homepaddock 15182 22632
12 No Right Turn 14892 19278
13 Music of sound 14692 19205
14 The REAL Steve Gray 13404 18257
15 Fields of Blood 13241 19311
16 TVHE 11748 12673
17 Offsetting Behaviour 11275 16588
18 Open Parachute 11118 14008
19 Liberation 10554 13789
20 Right Reason 9787 14084
21 Tikorangi: The Jury Garden 9692 12454
22 Keith Johnson Wellington NZ 9495 9695
22 MandM 9495 9695
24 13th Floor 9222 12795
25 Imperator Fish 8578 11956
26 Dark Brightness 8408 8580
27 Stats Chat 8161 12358
28 Hot Topic 7805 10657
29 Cycling in Christchurch 6858 9031
30 Aotearoa: A wider perspective 6144 7785
31 Throng New Zealand 5865 10119
32 Bill Bennett 5768 7664
33 Talking Auckland 5477 6866
34 Lindsay Mitchell 4441 5765
35 Lance Wiggs 4202 4910
36 Autism & Oughtisms 4079 4151
37 Chris no-frills 4041 5291
38 Mousehouse 3870 6130
39 Vomkrieg 3551 5931
40 Anglican down under 3277 4009
41 Otagosh 3141 6052
42 In the back of the net 3045 5399
43 Kiwi Cakes 2984 4020
44 Scepticon 2951 3296
45 Home education Foundation 2779 3825
46 Quote Unquote 2721 2997
47 On the Left 2656 3621
48 Windy Hilltops 2598 4043
49 Rodney’s Aviation Ramblings 2441 3204
50 Woodleigh Nursery 2382 5383
51 The Woolshed Wargamer 2340 3810
52 OracleNZ by Francisco Munoz Alvarez 2332 2513
53 Matte Shot 2119 3214
54 AmeriNZ 2087 2536
55 Save our Schools NZ 1994 2278
56 New Zealand Conservative 1979 2280
57 Crime Watch 1975 3375
58 Open Parachute @ SciBlogs 1923 2164
58 pasture Harmonies 1923 2164
60 Super Rugby Tips 1820 2452
61 Pdubyah – a life just as ordinary 1799 2830
62 Ultimate Student 1707 2281
63 Waiology 1694 2040
64 Canterbury Atheists 1570 1824
65 Eye on the ICR 1540 1982
66 Put ‘em all on an island 1401 1849
67 Undeniably Atheist 1377 1609
68 Scotty Donaldson 1206 1554
69 ROI Marketing 1138 1610
70 The Beehive Mandate 1111 1415
71 james lin’s blog 1095 1111
72 Blessed Economist 1070 1366
73 1066 1300
74 Notes from the bartender 1055 1188
74 Michael Jeans 1055 1362
76 Sustain:if:able Kiwi 1047 1560
77 ICT Teaching and Learning  1037 1446
78 Life of Andrew 1028 1197
79 Man of Errors 1026 1111
80 A conservative perspective 1021 1505
81 Works in progress 1003 1329
82 PM of NZ 970 1141
83 Stratford Aerodrome 955 1254
84 Einstein Music Journal# 953 1109
85 Socialist Aotearoa 923 1033
86 One Furious Llama 915 1126
87 A communist at large 911 1275
88 Keeping Stock 897 1210
89 Anne Free Spirit 870 1410
90 Episto 862 1309
91 Code for Life 835 953
92 misc.ience @ Sciblogs 817 920
93 Off the couch 816 1256
94 Wysiwygpurple’s Blog 804 1019
95 Life Behind the IRon Drape 721 1521
96 Kidney Punch  716 803
97 Derek’s blog 696 1097
98 Show your workings 637 863
99 A Bee of a Certain Age 628 774
100 Brennan McDonald 613 697
101 Brad Heap 598 740
102 Tauranga Blog 591 685
103 Life is not a race to be finished first 580 901
104 From the Earth’s End 576 762
105 Social Media & the 2014 Election 570 737
106 Two Minutes Sport 547 675
107 Tararua District Library 526 652
108 Ideologically impure 523 610
109 Stitchbird 514 879
110 The Meaning of Trees 507 610
111 Media Sport and Other Rantings 479 557
112 Polit Ecol 467 532
113 True Paradigm 466 569
114 Hitting Metal With A Hammer 455 591
115 Taradale Blog# 450 870
116 goNZo Freakpower Brains Trust 434 458
117 The IT Countrey Justice 433 534
118 Goings on at the Madbush Farm 408 486
119 sticK 404 463
120 Software development and stuff 401 408
121 Family integrity 399 425
122 Quietly in the backgroud 393 542
123 Riddled 382 551
124 Science in a van 379 440
124 Webweaver’s world 379 452
126 Perissodactyla 376 441
127 Artichoke 363 427
128 Tales from a Caffeinated Weka 359 604
129 roarprawn 355 463
130 Exile in New zealand 346 443
131 Halfdone 342 391
132 Skeptiocon @ Sciblogs 331 360
133 Room 5 @ Melville Intermediate School 330 390
133 Room One @ Auroa School 330 690
135 $100 Dialysis 324 389
136 Dad4justice 322 345
137 My thinks 316 371
138 Kutarere’s Blog  311 373
139 Glenview 9 305 324
140 Capitalism is bad 297 356
141 kiwiincanberra 294 409
141 Wokarella 294 409
143 The Gentically Insane 280 331
143 The Genetically Insane 280 331
145 Glennis’s Blog Page# 270 420
146 Samuel Dennis 268 273
147 Jo Blogs 263 365
147 Get Out Gertrude! 263 381
149 eyeCONTACT 253 320
150 MartinIsti Blog 252 648
151 Unity Blog 243 247
152 242 255
153 Creative Voice# 240 330
153 AnneKcam
240 420
155 Spatula Forum 237 270
156 The Little Waaagh! That Could 229 275
157 Cut your hair 219 221
158 Four seasons in one 211 224
159 Nelsonian’s life 210 300
160 Upstage 200 303
161 Pointless and adsurb 199 247
162 ElephaNZa  184 188
163 ZNO 179 236
164 Rest Area 300m 175 206
165 SmallTorque 172 191
166 The Fundy Post 163 195
167 Toni Twiss 161 161
168 The Catalyst 150 150
168 Korero Pt England 150 180
168 Manaia Kindergarten 150 300
168 Mountains of Our Minds# 150 180
172 Cimba7200’s thoughts 147 176
173 Lost Soul 146 166
173 Sharlene says 146 345
175 Springston School Library Blog 144 265
176 New Zealand Indian Fine Arts Society 139 151
177 This Mum Rocks 138 185
177 Write to travel 138 184
177 kiwi simplexity 138 150
180 Aphrodite rises 135 151
181 Dragonsinger 132 145
182 John Macilree’s Blog 128 132
183 Canvassing for opinion 126 146
184 NZ First Youth 122 150
185 King’s High School Library 120 270
186 Prior Knowledge  118 145
186 Ruggerblogger 118 176
188 Ellie Great 116 142
188 High voltage learning during the Christchurch earthquakes 116 177
190 The Well read Kitty 114 116
190 Millenium X 114 150
192 Fuller’s watch# 98 133
193 Grumpollie 97 118
194 Carolyn’s blog 93 125
195 At home with Rose 90 99
195 Virtual North 90 150
195 John Macilree’s Weblog# 90 120
195 The Official Ebenezer Teichelmann Blog# 90 120
199 Journey to a mini me 89 110
200 White & Black 88 109
200 Teaching the Teacher 88 109
202 Looking in the square 82 92
203 Sam Books and Thoughts 80 117
204 UpsideBackwards 79 84
205 Politicalisation 66 69
205 Whitireia Journalism School 66 78
207 Shelly van Soest Artist 64 67
208 Creative Collision 63 64
209 University of Otago, Law Library Blog 60 76
209 Pt England Scribes 60 90
209 Digital learning 60 120
209 ICTPD 60 60
209 Making IT Happen 60 90
209 Moving the crowd 60 60
209 James McKerrow – Surveyor 1834-1919# 60 60
216 jo russ photo diary 55 78
216 Something Interesting to read 55 73
218 Frontlawn 52 56
218 Reading the maps 52 111
220 TimG_Oz Blog 43 47
220 You’re Underthinking 43 44
222 round design 42 44
223 SageNZ 39 44
223 Oracle of Okarito 39 62
225 Discovery Time 38 53
225 Nathanael Baker 38 45
225 Social Policy Bonds Blog 38 46
228 Busy Peas 36 43
229 New Zealand female Firefighter calendar 35 41
230 The First Fifteen @ TIS 31 43
231 Sleeping with books 30 30
231 Kiwi Chronicles 30 30
231 But Now 30 30
231 Football Tragic NZ 30 30
231 Anticipating future impacts 30 30
231 Room 24, 2012 30 60
231 Chris Jillet – Mountaineer# 30 30
238 No Mum is an Island 29 45
239 Louis’ Outlook 27 31
240 KJT 26 26
240 ah! New Year’s Resolution 26 26
242 Palmerston North.ifo 24 30
242 global village governance 24 34
244 Moderation Blog 23 23
245 Mad Young Thing 22 23
246 Robtuckerpix’s Blog  21 21
247 The Secret Life of Russ  19 22
248 DMP Lead Free 18 26
249 Tangled up in purple 17 23
250 SilverSpikes Photography  16 16
251 ZL2UCX’s Blog 13 16
252 Think Beyond 12 14
253 Blair for Mayor 11 12
253 Liminal Spaces 11 11
255 A developing Geneticist 10 12
255 In this moment 10 11
257 Relatively science 9 11
258 TraLIS blog 7 8
258 Moments of Whimsy 7 8
258 Helen Heath 7 7
261 Scott & Sarah Kennedy 6 6
262 LoveColour Blog 5 5
262 Porirua EMO 5 6
264 Xenolexicon 4 12
264 Uncensored 4 7
266 Here I stand 3 3
266 Bob McKerrow – Wayfarer 3 3
266 Rambling Reflections 3 3
266 Unknown Future 3 3
270 ObservatioNZ 2 2
270 amiria [blog] 2 5
272 Born on State Highway 1 1 1
272 Roger Nome’s progressive Politics 1 1
272 Yea or Nay 1 1

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