Dr Paul Connett attacks the 2014 study ‘Community Water Fluoridation and Intelligence: Prospective Study in New Zealand’. You can watch the video here:
The main quote from Dr Connett is:
“It was an awful study, it has been debunked, because there was practically no control, you had 1400 people living in the fluoridated community and less than 100, and also the kids were taking fluoridated supplements, a lousy lousy study.”
Below is a point by point refutation, which should show that Dr Connett’s arguments do not hold water.
“It was an awful study…. a lousy lousy study”
Broadbent et al. (2014) is the currently the best paper on IQ at the recommended levels of fluoride in water. It used data from the Dunedin Multidisciplinary Study, which is world-renowned for the quality of its data and the rigour of its analysis.
The strict 2015 ‘Health effects of water fluoridation‘ review by the Health Research Board said of the study
“…the current review identified one original paper in a non-endemic area (New Zealand) that aimed to clarify the relationship between CWF and IQ by Broadbent et al. This is a high-quality prospective cohort study of a general population sample…”.
“Practically no control”
The study controlled childhood factors associated with IQ variation, such as socio-economic status of parents, birthweight and breastfeeding, secondary and tertiary educational achievement and sources of fluoride exposure other than community water fluoridation (CWF). They also controlled for a similar set of confounders to those controlled by Meier et al (2012) in their study of cannabis exposure and IQ, which found that persistent cannabis users show neuropsychological decline. Does Dr Connett have a problem with this study?
“You had 1400 people living in the fluoridated community and less than 100”
The number of study members who had never resided in a fluoridated area was 99, and the number who had, was 891, but this does not indicate a low ability to detect an effect. There is no such thing as no fluoride exposure; that is, fluoride is naturally present in both soil and water. The study had more than enough power to conduct analyses that distinguished between high and low fluoride exposure, and to model the relation with IQ.
“The kids were taking fluoridated supplements”
This was controlled for, and no significant differences in IQ were found. Those with high total fluoride intake had slightly higher IQs than those with low total fluoride intake. The authors of the study released this graph (below).
“It has been debunked”
It hasn’t. The Fluoride Action Network released a press release criticising the study and calling it “flawed”:
However, maybe Dr Connett never got the memo, as the authors of the study debunked every main point in the ‘On Tap’ issue 10.
The authors have also written in response to criticism in Journals, here and here. They re-ran their analysis, taking into account both suburb and distance from the city centre, more details on total fluoride intake, the interaction between breastfeeding (including duration), etc. The results were no meaningful change of significance, effect size, or direction to their original findings.
The conclusion of the study still holds up:
“The findings do not support the assertion that fluoride exposure in the context of CWF can affect neurologic development or IQ. Study members who lived in areas with CWF before age 5 years had slightly higher IQs (on average) in adulthood than those who had not, but this difference was non-significant”
On top of this conclusion, the study also had sufficient power to explore differences in the experience of dental caries. The study observed significantly fewer caries-affected teeth in both childhood and adulthood among those who resided in CWF areas as children.
Excellent, Daniel. It is always comical to see Connett try to discredit Broadbent on one hand, while on the other propping up the 27 Chinese Studies which were so absurdly flawed that even Grandjean and Choi were forced to admit they could not be used to evaluate fluoridation in the US, as Connett does anyway.
Steven D. Slott, DDS
Thanks Steve. This piece annoyed me just too much to not write about it. I can’t believe he said such things and continues to use some of the worst studies to prove IQ is affected.
I also sent this to the Denver Water Board. I believe feedback closes in a couple of hours, if you haven’t sent anything through.
The Denver board needs to understand about Connett. I recommended to a local citizen there to send the board a link to Ken’s debunking of Connett’s distortions, which he did, so I’m glad they will also see yours. Keep up the awesome work!
Excellent post Daniel. It’s good to see people like this called out with facts.
DianeDi your comment hasn’t been accepted. Please don’t spam links that have nothing to with this article.
Daniel Ryan – Boo f@$#ing who – you liar !!! Give my best regards to Troll face Steven Slott !
How am I lying? You spam 21 links of youtube videos that you have copied and pasted. You have posted this comment on other comment sections of other websites. There was no discussion with those links.
If you want to discuss the above topic on that Dr Connett distorts the Dunedin IQ fluoride study then go ahead. We are open to all sides of the discussions here, but we don’t want to be gish galloped especially when it has nothing to do with the subject.