Fluoride - "an emerging neurotoxin" - The Lancet 2007

An article in The Lancet, the world's oldest and independent medical journal describes Fluoride as "an obvious candidate" for classification as "an emerging neurotoxin".

The article is closely connected with the Scientific Consensus Statement on Neurodevelopment disorders.

The paper’s focus is on neurotoxicity in relation to the developing brain, particularly in the developing foetus. The authors discuss two types of substance:

  1. Acknowledged, proven neurotoxins affecting the developing brain, such as lead, arsenic, and polychlorinated biphenyls (PCBs)
  2. Substances not currently classified as neurotoxic to adults, and for which there is emerging evidence that they are neurotoxic to the developing brain, hence children and the unborn.

After discussing proven neurotoxins, Fluoride is discussed in a section of the paper entitled “Emerging Neurotoxic Substances”, and is discussed as “one of three obvious candidates” (the other two being perchlorate and manganese).

What is highly important is that the researchers found that Fluoride appears to be developmentally neurotoxic in both high and very low exposures.

There appears a little confusion in the article as a panel on page 3 lists “fluoride compounds” as “chemicals known to be neurotoxic in man”. The following, from another article co-authored by Grandjean explains things more clearly. The key passage is, after identifying proven neurotoxins:  “From this evidence, including our own studies on some of these substances, parallels may be drawn that suggest that fluoride could well belong to the same class of toxicants, but uncertainties remain.”

Potential for developmental fluoride neurotoxicity

The foetus and the child are particularly vulnerable to pollution. The foetus shares the mother’s exposure and accumulated body burden of pollutants, and some chemicals are transferred to the infant via human milk. Occurrence of severe dental fluorosis in a child, whose mother had worked at the Danish cryolite factory suggests that fluoride transfer from mother to child takes place. The central nervous system may be a target organ, as suggested by laboratory animal studies. During early life, cell differentiation, multiplication and migration must happen in a particular sequence and at certain times to create optimal brain functions of the mature organism.

Thus, developmental exposure to neurotoxic substances can cause serious disease and also widespread loss of IQ. While fluoride exposure may cause neurotoxicity in adults, the evidence on developmental neurotoxicity in humans is uncertain and is mainly based on studies carried out in China. Exposures were generally assessed on a community basis, and cross-sectional examinations of neuropsychological test performance were related to water-fluoride concentrations. In humans, only five substances have so far been documented as developmental neurotoxicants: lead, methylmercury, polychlorinated biphenyls, arsenic, and toluene. From this evidence, including our own studies on some of these substances, parallels may be drawn that suggest that fluoride could well belong to the same class of toxicants, but uncertainties remain. At least 200 industrial chemicals are known to cause brain toxicity in humans, mainly in adults, and they must also be suspected to harm the developing brain. Because of the individual and societal importance of optimal brain function, recognition of developmental neurotoxicity is a public-health priority, and further evidence on fluoride is needed.”

Authors: Choi Anna L, Grandjean Philippe.
Correspondence: Harvard School of Public Health, Boston, MA, USA; University of Southern Denmark.