Fluoride Action Network


In a previous investigation it was established that in pregnant women drinking water with a medium  fluoride concentration, 0.5-0.6 ppm F, the mean F-value of the placenta is significantly higher than that in the cord blood or the maternal blood. The findings under such conditions suggest that the placenta accumulates fluoride and regulates its transfer to the fetus.1

In  the present study the role of the placenta was further investigated when the fluoride intake during pregnancy from drinking water was low, high, and medium but supplemented by fluoride taken in tablet form.

Materials and Methods

Samples of maternal blood, cord blood, and whole placental tissues were obtained at normal deliveries from three groups of women:

GROUP I. Thirty-nine women from Upper Galilee and Tel-Aviv area who used drinking water containing 0.06-0.15 ppm F (low concentration).

GROUP II. Twelve women from Kiriarth-Chaim in the northern coastal plain, who used drinking water containing 0.6-0.9 ppm F (high concentration).

GROUP III. Eighteen women from Jerusalem, who in addition to drinking water containing 0-.5-0.6 ppm F (medium concentration) also received one sodium fluoride tablet* of 1/2 mg F content each day during the second half of pregnancy. It was decided to supplement tablets in Jerusalem, where supervision was easier.

All subjects lived in the respective areas during the whole period of pregnancy. Placentas were obtained at normal deliveries occurring at full term. The whole placenta was analyzed in each case to avoid errors due to unequal distribution of fluoride in the tissue.1 The net weights of the placenta ranged from 315 to 755 gm.

FLUORIDE DETERMINATION. About 15 ml blood and whole placenta were each made alkaline with fluoride-free Ca(OH)2 solution to avoid fluoride losses. The samples were evaporated to dryness and ashed at about 450° C. The ashed samples were transferred to the distillation apparatus previously described,2 and chlorides were precipitated with Ag2So4. Fluoride was then steam-distilled in presence of H2SO4 at 135° C. In the concentrated distillate, fluoride was determined colorimetrically by the color-fading reaction of a violet-iron salicylate complex, as described by Voegtlin and Hodge3 and by Cremer and Voelker.4 The experimental error of this method for blood and placenta samples is ±0.03 ppm F.


The results are summarized in Table 1.

LOW F-INTAKE. The mean fluoride value of the cord blood was higher than the mean fluoride values of the placental tissue and maternal blood. The difference between the mean placental tissue was significant (p <0.01). The mean fluoride values of the placental tissue and maternal blood were not significantly different.

HIGH F-INTAKE. The differences between the mean fluoride values in the placental tissue, cord blood, and maternal bloodat high F-intake, from drinking water or fluoride tablets, were insignificant. In the table the two groups are considered there…

*Original abstract online at https://journals.sagepub.com/doi/10.1177/00220345640430050801