Luke J. Caries Research. 2001 Mar-Apr;35(2):125-8. (See study)
The purpose was to discover whether fluoride (F) accumulates in the aged human pineal gland. The aims were to determine (a) F–concentrations of the pineal gland (wet), corresponding muscle (wet) and bone (ash); (b) calcium–concentration of the pineal. Pineal, muscle and bone were dissected from 11 aged cadavers and assayed for F using the HMDS–facilitated diffusion, F–ion–specific electrode method. Pineal calcium was determined using atomic absorption spectroscopy. Pineal and muscle contained 297±257 and 0.5±0.4 mg F/kg wet weight, respectively; bone contained 2,037±1,095 mg F/kg ash weight. The pineal contained 16,000±11,070 mg Ca/kg wet weight. There was a positive correlation between pineal F and pineal Ca (r = 0.73, p<0.02) but no correlation between pineal F and bone F.
By old age, the pineal gland has readily accumulated F and its F/Ca ratio is higher than bone.
This study has added new knowledge on the fate and distribution of fluoride in the body. It has shown for the first time that fluoride readily accumulates in the human pineal gland although there was considerable inter-individual variation (14-875 mg F/kg). By old age, the average pineal gland contains about the same amount of fluoride as teeth (300 mg F/kg) since dentine and whole enamel contain 300 and 100 mg F/kg, respectively [Newbrun, 1986].
Unlike brain capillaries, pineal capillaries allow the free passage of fluoride through the endothelium. If there had been a bloodbrain barrier in the pineal, it would have prevented the passage of fluoride into the pinealocytes and the pineal fluoride content would have been similar to or lower than muscle. This was obviously not the case: the fluoride concentration of the pineal was significantly higher (p<0.001) than muscle. The high fluoride levels in the pineal are presumably due to the large surface area of the HA crystallites both intra- and extracellularly. In addition, the pineal has a profuse blood flow and high capillary density; pineal blood flow (4 ml/min/g) is second only to the kidney [Arendt, 1995].
The extent of pineal calcification also varied between individuals: ranging from 4,600 to 37,250 mg Ca/kg wet weight. One of the aged pineals had very little precipitation. This supports the age independence of pineal calcification and agrees with previous studies [Cooper, 1932; Arieti, 1954; Tapp and Huxley, 197 1; Hasegawa et aL, 1987; Galliani et al., 1990]. The estimated fluoride concentration of pineal HA was 9,000 ± 7,800 mg/kg. The F/Ca ratio was higher in pineal HA than in corresponding bone (fig. 2). The extremely high level of substitution in the crystal structure of pineal HA by fluoride illustrates the readiness with which fluoride replaces the hydroxyl ion in the HA crystal. By old age, pineal HA has a higher fluoride content than other biological apatites. Unlike pineal concentrations of magnesium, manganese, zinc and copper, which, although very high, were generally within the limits found in bone and teeth [Michotte et al., 1977].
In conclusion, this study presented evidence that fluoride readily accumulates in the aged pineal. Fluoride may also accumulate in a child’s pineal because significant amounts of calcification have been demonstrated in the pineals from young children [Cooper, 1932; Wurtman, 1968; Kerényi and Sarkar, 1968; Tapp and Huxley, 197 1; Doskocil, 1984]. In fact, calcification of the developing enamel organs and the pineal gland occur concurrently. If fluoride does accumulate in the child’s pineal (this needs verification), the pinealocytes will be exposed to relatively high local concentrations of fluoride. This could affect pineal metabolism in much the same way that high local concentrations of fluoride in the developing enamel organ affect ameloblast function. Research is presently underway to discover whether fluoride affects pineal physiology during childhood: specifically pineal synthesis of melatonin.