NZ Fluoridation review – Response to Micklen

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:

• Review by Royal Society of NZ and the Office of the Prime Minister’s Chief Science Advisor:
  

  Health Effects of Water Fluoridation: a Review of the Scientific Evidence.

• Critique by Fluoride Free NZ organisation: International Peer Review of the Royal Society/PM Science Advisor Office Fluoridation Review. 
• Anti-fluoride activists define kangaroo court as “independent”
• The farce of a “sciency” anti-fluoride report
• Peer review of an anti-fluoride “peer review”
• Cherry-picking and misinformation in Stan Litras’s anti-fluoride article
• Fluoride Free NZ report disingenuous – conclusion 
• Did the Royal Society get it wrong about fluoridation?

References

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.