Refute of Fluoridation Opponents’ Claims of Adverse Effects on Pineal Gland

Opinion of Dr. Michael Foley of Queensland Health Australia:

Jennifer Luke’s 1997 PhD studied the effects of fluoride on the pineal gland.  The pineal gland is near the centre of the brain, but outside the blood brain barrier that restricts the passage of fluoride into the central nervous system.  It’s a mineralising tissue containing calcium concretions called corpora arenacea (brain sand).  These concretions contain hydroxyapatite crystals (no idea why) and those crystals are visible on x-rays and other scans.  Because they contain hydroxyapatite, Luke hypothesised that they might also contain high fluoride levels.  Perfectly legitimate research question.  The first part of her PhD formed the basis of her Caries Research paper.  She examined the pineal glands of 11 cadavers.  As expected, they contained fairly high levels of fluoride, although the levels varied significantly.  She found that pineal fluoride levels are not indicators of long term fluoride exposure.  Interesting (and a bit worryingly), although she dissected 11 cadavers, her graph in Fig 1 only included results for 10 pineal glands.  How did she, her PhD supervisors and Caries Research reviewers not pick that one up?  Looks sloppy to me.

The second part of her research is more often quoted by anti-fluoridationists.  Luke found that Mongolian gerbils exposed to high fluoride levels produced lower levels of melatonin metabolites than those exposed to low fluoride levels.  It is thought that a fall in melatonin levels in children could provide the trigger for the onset of puberty. Anti-fluoridationists use this information to imply that fluoridated water causes earlier onset of puberty. They even cite one of the early fluoridation studies, noting that “girls in fluoridated Newburgh were reaching menstruation, on average, five months earlier than the girls in unfluoridated Kingston”.  These claims should be treated with skepticism.  The age at which girls reach puberty has been reducing over the last fifty years (about three months per decade) in every country in which it has been measured. It does not appear to be related to fluoride exposure, and there has never been any speculation among medical specialists, let alone published research, suggesting such a link.  The mischievous Newburgh-Kingston puberty claim arises from a 1956 study that subjected children from the two cities to a wide range of medical and physical examinations ten years after the introduction of fluoridation in Newburgh.  When comparing onset of puberty, only a very small sample of girls was taken; 37 girls in fluoridated Newburgh and 26 in Kingston.  Their ages were not exact, only being calculated to the nearest birthday. The authors correctly stated that “No statistical difference could be demonstrated in this difference, nor in the difference between the two cities in the proportion of girls who had passed the menarche.”  The study concluded that “No differences of medical significance could be found between the two groups of children; thus further evidence was added that already available on the safety of water fluoridation.”  I’ll be the first to admit that the very early medical examinations were fairly perfunctory, but their lack of any concerning findings has been confirmed by dozens of systematic reviews since.

Luke concludes her PhD by stating that “Whether or not fluoride interferes with pineal function in humans requires further investigation”.  Hardly the damning indictment of fluoride claimed by the anti-F nutters.

Despite Luke completing her PhD in 1997 and since then actively seeking further publications (I read this many years ago, but can’t now remember where), the second part of the research has yet to be accepted by a scientific journal or studied by experts in the field.  It looks like a weak PhD to me.  Caries Research is a poor fit for her pineal gland paper, and my guess is that it was rejected by other journals before it somehow slipped through the Caries Research reviewers.  

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