The Thyroid and Fluoride

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The Thyroid and Fluoride

by Professor Paul Connett

 

 

Dear CTM rs,

 

This is the sixth in a series of 14 bulletins in which I will be focusing on

public health warnings on fluoridation which are being ignored by public health

officials as well as many non-governmental organizations otherwise engaged in

protecting the public health. I urge you to forward this, and the other public

health warnings to your local, provincial or federal health officials and ask

them for their response. Copy your letter to your state and federal

representatives and get them engaged in your discussions, especially if you

sense you are getting the run around from the health officials.

 

Public Health Warning on Fluoridation, 6: The thyroid gland and fluoride.

 

The literature dealing with the interaction between fluoride and the thyroid

gland has a very long history, stretching back to a paper written in 1854 by

Maumene who linked goiter in dogs with exposure to fluoride. The following URL

links to a summary of that history

http://64.177.90.157/pfpc/html/thyroid_history.html

 

I do not pretend to know enough about either this history or the detailed

functioning of the thyroid gland to offer much insight into this issue. However,

it is an extremely important area and it warrants far more attention from

governments promoting fluoridation than it currently receives, which is

practically zero! Millions of Americans are impacted by thyroid dysfunction, and

if only a small fraction of these have their condition caused by, or worsened

by, fluoride it is a very serious matter indeed.

 

There are four important lines of evidence that fluoride interferes with the

thyroid gland.

 

1) The condition known as " goiter " which involves a gross swelling of the

thyroid gland, which in turn produces very marked swellings in the neck, is

known to be caused by iodine deficiency. However, it has also been found to

occur in areas where there are adequate supplies of iodine, but where there's an

excess fluoride in the water.

 

2) Starting in the 1930s and continuing through to the late 1950's sodium

fluoride was used to lower the activity of the thyroid gland for those suffering

from hyperthyroidism (i.e. over active thyroid gland). The obvious question then

becomes, if fluoride lowers the activity of an overactive thyroid gland what

does it do to a normal or underactive thyroid gland?

 

3) It has been known for a long time that one of the consequences of iodine

deficiency in mothers is an increased risk of mental retardation in their

children. With the advent of iodized salt, this is a less frequent occurrence in

industrialized countries. However, studies from China indicate that even a

moderate amount of fluoride exposure can exacerbate the effects of low iodide's

impacts on the developing brain.

 

4) It has been known for a long time that fluoride mimics the action of the

thyroid stimulating hormone (TSH). Because TSH sends its message across the cell

membrane of the thyroid gland via G-proteins, a candidate mechanism for

fluoride's action would be fluoride's well established ability (See reviews by

Strunecka & Patocka, 1999; and Li, 2003), in the presence of a trace amount of

aluminium, to switch on G-proteins.

 

Taking these lines of evidence one at a time.

 

1) Endemic Goiter (also spelled goitre) and fluoride.

 

In a 90 page report entitled " Endemic Goitre in the Union of South Africa and

some Neighbouring Territories " , prepared for the Department of Nutrition for the

South African government, Dr. Douw Steyn and colleagues concluded that there

were two separate causes for endemic goiter. In their summary, they state, " In

the Union of South Africa endemic goitre is caused by: (1) a primary iodine

deficiency in the drinking water and soil, and most probably in the food; and

(2) excessive quantities of fluorine in subterranean drinking-water in spite of

super sufficiency of iodine in the waters. " (See

http://www.slweb.org/south-africa.goitre.html )

 

The areas with endemic goiter caused by excess fluoride were located in the

Northwest part of South Africa. In 1999, Jooste et al repeated Steyn's findings

when they reported endemic goiter in the absence of iodine deficiency in

schoolchildren of the Northern Cape Province. A similar relationship between

excess fluoride exposure and goiter has been reported in England (Wilson 1941),

in the Punjab region of India (Wilson 1941), in Nepal (Day and Powell-Jackson,

1972) and in Gujarat, India (Desai 1993). Other studies, however, have failed to

find this relationship (see Burgi 1984).

 

 

2) Treating hyperthyroidism with sodium fluoride tablets.

 

What is striking about the doses of fluoride used to treat hyperthyroidism is

how small they were. Galletti and Joyet (1958) found that a daily dose of just

2.3-4.5 mg of fluoride per day was enough to reduce the basal metabolism rate

(BMR) of hyperthyroid patients and alleviate their condition (see paper at

http://www.fluoridealert.org/galletti.htm ). This dose (2.3-4.5 mg/day) will be

exceeded by many people living in a fluoridated area. The US Department of

Health and Human Services (DHHS,1991) estimates that an adult in a fluoridated

community receives between 1.6 and 6.6 mg of fluoride per day from all sources

combined.

 

In a World Health Organization review (Fluoride and Health, WHO, 1970), Semole

cites evidence from Korrodi et al (1956) that, in normal human subjects,

fluorides have no effect on the thyroid. He then asks, " Why does sodium fluoride

exert a mild antithyroidal effect in hyperthyroidic patients if it is inactive

in normal persons? Nobody knows. "

 

However, the claim that fluoride has no effect on normal thyroid function may

have been premature. According to a study conducted by Bachinskii (1985),

prolonged consumption of water with 2.3 ppm fluoride produced changes in thyroid

function, not only in people with hyperthyroidism but in people with normal

thyroid function as well. Bachinskii writes in the abstract of his paper:

 

" Altogether 123 persons were examined: 47 healthy persons, 43 patients with

thyroid hyperfunction and 33 with thyroid hypofunction. It was established that

prolonged consumption of drinking water with a raised fluorine content (122 +/-

5 mumol/l with the normal value of 52 +/- 5 mumol/l) by healthy persons caused

tension of function of the pituitary-thyroid system that was expressed in TSH

elevated production, a decrease in the T3 concentration and more intense

absorption of radioactive iodine by the thyroid as compared to healthy persons

who consumed drinking water with the normal fluorine concentration. The results

led to a conclusion that excess of fluorine in drinking water was a risk factor

of more rapid development of thyroid pathology. "

 

Unfortunately, Bachinskii's full study was published in Russian, and we do not

have a translation. However, it would be an easy matter for any government to

get a translation of this work and to pursue the details of this study and

repeat it if there is any doubt in the matter.

 

3. Lowering of IQ in China.

 

It is well established that the pituitary/thyroid system is important in the

early mental development of children thus if fluoride interfered with the

thyroid it could, among other things, result in lowered IQ in children. In this

respect, the results of a UNICEF sponsored study of mental retardation, IQ and

thyroid hormone status in children in areas endemically low in iodide are

particularly revealing. Lin Fa-Fu et al. (1991) found in one region of China

that even a modest amount of fluoride in the water (i.e. 0.91 ppm versus 0.34

ppm) led to an even greater reduction in IQ and the frequency of mental

retardation, than simply low iodide by itself. (See paper at

http://www.fluoridealert.org/idd.htm )

 

Yang et al (1994) further investigated the effect of iodide and fluoride on IQ

and hormonal status in areas of high iodide and high fluoride. From their study

the authors concluded that their results " indicate that high iodine and high

fluorine exert severe damage to human body. " Compared to controls, children had

higher dental fluorosis rates; markedly lower iodine-131 uptake; higher serum

TSH levels, and slightly lower average IQ, with 16.7% placed in a category

labelled " low intelligent. " We only have the abstract in English, the rest of

the paper is in Chinese.

 

4. TSH, fluoride and G-proteins.

 

Just how fluoride impacts the thyroid gland is not clear. We know that, in the

presence of a trace amount of aluminium, fluoride switches on G-proteins, thus

sending messages normally delivered by water soluble hormones. TSH is one of the

water soluble hormones which is mimicked by aluminium fluoride. But the puzzling

thing about this is that one would expect that this would lead to an activation

of the thyroid gland not deactivation (as in the case of someone with

hypothyroidism).

 

A clue to this puzzle may have come in 1994 in a paper by Tezelmann et al. These

researchers using Chinese hamster ovary cells, report that fluoride increases

intracellular cAMP concentration (the secondary messenger produced as a result

of switching on G-proteins), but the end result was desensitisation of the

receptor for the thyroid stimulating hormone (TSHr). In other words, the

fluoride begins by stimulating the cell but the end result was that it led the

cell to become less responsive to the normal stimulation by TSH. The authors

state that, " Desensitisation or decreased response to the same (homologous) or

other stimuli (heterologous) is a well known process. Homologous desensitisation

to TSH has been demonstrated in normal thyroid tissue. "

 

I will be returning to the activation of G-proteins in a later health warning as

well as its ability to lower IQ in another.

 

Meanwhile, various recent government sponsored reviews have given this topic

very short shrift. The York Review (McDonagh et al., 2000) looked at only two of

the goiter studies (Jooste, 1999 and Gedalia, 1963). They didn't use a weight of

evidence approach, bringing in the clinical and biochemical studies above. The

Irish Fluoridation Forum (2002) didn't do any review of primary studies on

health except dental fluorosis and four bone fracture studies. The CDC (1999)

reviewed no health studies beyond citing the NRC (1993) review and the NRC(1993)

review didn't consider impacts on the thyroid system, nor did the First draft of

the WHO review (Environmental Health Criteria 227: Fluorides, 2002).

 

I welcome any corrections or comments, especially if readers know of any

government review since WHO (1970) that has discussed fluoride's impact on the

thyroid gland.

 

 

 

 

 

 

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