UK report recommends further research on water fluoridation and healthBMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7364.564/b (Published 14 September 2002) Cite this as: BMJ 2002;325:564
All rapid responses
As reported by the BMJ (1), the UK Medical Research Council (MRC)
released its long-awaited report on the health effects of fluoridation on
September 5, 2002.
The report is entitled "Water Fluoridation & Health" and is available
at the website of the MRC (2).
WHY THIS REPORT?
As a result of earlier "findings" by the York NHS Review (2000) (3),
the MRC had set up a Working Group to identify "areas of uncertainty
regarding the balance of benefits and risks of water fluoridation", and to
make appropriate recommendations for further research to address any
The MRC based this report on the studies which were admitted by the
York Review according to its "inclusion criteria" for the review into the
efficacy and safety of the fluoridation of drinking water (3).
Please note that in 1999 we, as parents of children who have suffered
from fluoride poisoning, submitted over 100 studies to the York Review,
all dealing with fluoride effects upon thyroid hormones, i.e. inhibition
of hormone conversion in peripheral tissue, inhibition of hormone
transport, de-iodination effects, actual thyroid gland damage (goitre),
As thyroid dysfunction was usually seen in our children once the
appropriate tests were done (complete thyroid panel), we considered this
of utmost priority
in any assessment of fluoride toxicity.
We notified York of the fact that all documented symptoms associated
with fluoride poisoning were identical to those observed in thyroid
dysfunction. We sent a detailed list of over 150 such symptoms and
associations to all panel members, along with scientific references. This
included information on the enamel condition known as "dental fluorosis"
For over 80 years it has been known that the enamel disturbances
observed in dental fluorosis are identical to those found in thyroid
dysfunction (5). That fluoride and iodine have mutually interactive
effects upon dental fluorosis has been shown many times since in animals
(6,7,8) as well as humans (9).
Meanwhile, the field of dentistry STILL doesn't know
the exact mechanisms which lead to dental fluorosis (i.e 10,11), yet it
does not hesitate to declare the condition a mere "cosmetic effect" only.
When challenged, dentistry cannot cite ONE study which they have ever
conducted comparing the overall health of children afflicted with dental
fluorosis to those without. Needless to say, endocrinologists would never
declare a goitre to be of cosmetic concern only, would they?
We also asked the York Review to consider the effects of water
fluoridation in the context of TOTAL intake, as tea consumption is
obviously very high in the UK, and UK tea may easily contain 5 mg of
fluoride per litre (12), ensuring fluoride intake way above any so-called
"optimal" dose for the majority.
The York Review rejected our submission on the grounds that the data
consisted of fluoride sources OTHER than water fluoridation, such as
tablets, tea, injections, topical applications, air, etc.. There was data
from humans, animals, as well as in-vitro experiments.
We were told that the protocol did not allow for this to be
considered, and that protocol could not be changed. When we notified the
Committee that the protocol - as posted at the time - actually stated that
studies on "fluoride at any concentration provided from sources other than
drinking water" were to be included, the York Review simply
changed its protocol (paragraphs 4.2 and 4.4) to state that only drinking
water studies were to be included in its review, thus effectively avoiding
the inclusion of our data.
[Please also note that these particular protocol changes were never
addressed in Appendix M of the Review (13) which supposedly lists all
protocol changes undertaken during the entire review process.]
The 1999 exchange between the PFPC and the York Review is available
on the Internet (14).
Now to the MRC report. It always takes a lot more effort and time to
show how someone has erred, and this 48-page report is no exception. This
report is so faulty that it would take an incredible effort to address it
all in detail. Considering the time restrictions we will only focus on the
information dealing with the thyroid issue.
Regarding fluoride effects upon the thyroid, the MRC report offers
merely one short paragraph [5.3.7]:
"The York review listed three studies in which goitre was the outcome
of interest. Two of these studies (Gedalia & Brand, 1963; Jooste et
al) found no significant association with water fluoride level. The third
(Lin et al, 1991) found a significant positive association between
combined high fluoride/low iodine levels and goitre. However, because
this study looked at combined fluoride/iodine uptakes, and has not been
published in a peer-reviewed journal, the findings should be treated
cautiously. Further work on this aspect is of low priority."
Why the York Review only listed three studies is anyone's guess, as
there are many recent studies from around the world documenting effects of
fluoride in drinking water upon thryoid function (i.e., 9, 15).
We shall address the last study mentioned by the MRC. We had
submitted the Lin Fa-Fu et al. study NOT through the York website as is
claimed by York, but as part of an Open Letter which was sent to all panel
members on September 30, 1999 (16).
Both the York Review and the MRC state that this study looked at
goitre as the outcome. It did not.
To state this as fact not only shows incompetence, but one is led to
wonder if the MRC actually read the paper at all.
Goitre prevalence was only mentioned "in passing".
Lin Fa-Fu et al. investigated what is now called "subclinical endemic
cretinism", a term which is used to describe the milder forms of somatic
and psychomotor maldevelopment known to be the result of iodine
deficiency. Detailed thyroid tests were done including TSH, rT3, rT3/T3
ratio, I131 uptake, as well detailed IQ and hearing tests. Dental
fluorosis was also investigated, as was bone retardation.
We urge all to read the actual paper as one may get a picture as to
how these factors were related. The study has been posted on the Internet
Lin Fa-Fu et al did NOT investigate HIGH fluoride as stated by the
MRC. The levels described as "high" in the Lin Fa-Fu paper were 0.88 ppm -
LESS than is considered "optimal" for water fluoridation, which is 1
ppm (-> part-per-million, or 1 mg per liter)
LACK OF PEER REVIEW?
Regarding lack of "peer-review", please note that the Lin Fa-Fu et
al. study was a three-year project funded by UNICEF, undertaken by the
Chinese equivalent to the U.S. CDC, and was published in the August 1991
edition of the ICCIDD Newsletter, the official publication by the
International Council for the Control of Iodine Deficiency Disorder.
[ICCIDD is a group made up of a network of researchers, epidemiologists
and experts in public health and salt, who work with governments at the
national level to implement iodized salt programs, which are in place
worldwide. Dr. Jooste is the secretary.]
Regarding the studies by Jooste et al and Gedalia & Brand we
invite you to look at the data yourself, as posted by the York Review
(18,19). You may draw your own conclusions as to their "significance". The
trend is most obvious:
the higher the fluoride content in water, the higher the goitre
Regarding "research priorities" the MRC states that the effects of
fluoride upon thyroid hormones are of low priority. How anyone who doesn't
even know the mechanisms leading to dental fluorosis - although clearly
related to thyroid dysfunction - can make such a statement is
beyond belief. There are easily over 40,000 biochemcal studies available
on MEDLINE alone, describing in great detail fluoride effects upon thyroid
-hormone-dependent events (20).
On May 22, 2002, the WHO reported that some 50 million children in
2001 were born with mental and physical delays caused by "iodine
deficiency" (21), an issue of "most urgent concern".
Over 80 years ago it was found that "iodine deficiency" in many areas
of the world was not due to lack of iodine at all, but to excess intake of
fluoride from water, food, and air. These findings led to the highly
successful use of fluoride medications in the treatment of hyperthyroidism
(Basedow) (22). Basedow's Disease was characterized by high iodine levels
in blood. After many tests showed that fluoride reduced such iodine
levels, fluoride therapy became the first line of treatment for over three
decades in Germany and other countries.
In India alone 66 million people suffer from fluorosis, 6 million of
which are children. UNICEF has now identified 25 countries where fluorosis
is endemic (23). A cure is not known. It is high time that this public
health issue gets addressed properly.
Recently Belgium has become the first EU country to ban fluoride in
tablets, drops, chewing gum, and salt (24). In India the Health Ministry
warns the people to stay away from fluoride toothpaste and black tea (25).
These are steps in the right direction.
The MRC has failed miserably.
Andreas Schuld, Trent Harris & Wendy Small
Parents of Fluoride Poisoned Children (PFPC)
Vancouver, BC, Canada
1) Mayor S - "UK report recommends further research on water
fluoridation and health"
BMJ 325: 564b (2002)
2) MRC, 2002 - "Water Fluoridation & Health"
3) University of York NHS Center for Reviews and Dissemination
"Fluoridation of Drinking Water: a Systematic Review of its Efficacy and
4) Symptoms/Associations of Fluoride Poisoning & Thyroid
5) McKay, FS - "Progress of the year in the investigation of mottled
enamel with special reference to its association with artesian water" J
Natl Dental Assn 5:721 (1918)
6) Wilson RH, DeEds F -"The Synergistic Action Of Thyroid On Fluoride
Toxicity" Endocrinology 26:851 (1940)
7) Zhao W, Zhu H, Yu Z, Aoki K, Misumi J, Zhang X - "Long-term
Effects of Various Iodine and Fluorine Doses on the Thyroid and Fluorosis
in Mice" Endocr Regul 32(2):63-70 (1998)
8) Zhao WY -"A preliminary study of the interaction of iodide and
fluoride in experimental iodide-goiter and fluorosis" Chung Hua Yu Fang I
Hsueh Tsa Chih 22(3):146-8 (1988)
9) Desai VK, Solanki DM, Bansal RK - "Epidemiological study of goitre
in endemic fluorosis district of Gujarat" Fluoride 26 (3):187-190 (1993)
"We examined 22,276 individuals for presence of goitre and dental
fluorosis and estimated the fluoride and iodine content of their drinking
water. Overall goitre and dental fluorosis prevalences were 14.0% and
12.2%, respectively, and were significantly and positively correlated. No
significant relationship was observed between water
iodine level and goitre. In the study area only 0.3% of cases were visible
goitre (Grade-II and above) and all goitre cases were euthyroid. This
suggests that fluoride-induced goitres are brought about by anatomical or
structural changes rather than functional changes."
10) Kirkham J, Brookes SJ, Zhang J, Wood SR, Shore RC, Smith DA,
Wallwork ML, Robinson C - "Effect of experimental fluorosis on the surface
topography of developing enamel crystals" Caries Res 2001 Jan-Feb;35(1):50
11) Gerlach RF, de Souza AP, Cury JA, Line SR - "Fluoride effect on
the activity of enamel matrix proteinases in vitro" Eur J Oral Sci
12) UK TEAS
13) York Review: APPENDIX M
14) UK REVIEW
15) Bachinskii PP, Gutsalenko OA, Naryzhniuk ND, Sidora VD, Shliakhta
AI - "Action of the body fluorine of healthy persons and thyroidopathy
patients on the function of hypophyseal-thyroid the system." Probl
Endokrinol 31(6):25-9 (1985)
16) OPEN LETTER #2
17) Lin Fa-Fu, Aihaiti, Zhao Hong-Xin, Lin Jin, Jiang Ji-Yong,
Maimaiti, and Aiken - "The Relationship of a Low-Iodine and High-Fluoride
Environment to Subclinical Cretinism in Xinjiang" ICCIDD Newsletter,
Volume 7 Number 3
18) York Review: APPENDIX C12
19) York Review: APPENDIX C11
20) PFPC: 40,000 biochemical studies:
21) WHO Report on IDD (May 22, 2002)
22) PFPC Newsletter #3 (1999)
24) HUME Magazine: Interview with Health Minister Aelvoet (July 30,
25) Times of India - "Book by Minister" (Aug.8, 2001)
Competing interests: No competing interests
The News item by Mayor, and the Rapid Responses(RR’s) to the
article, show that products containing fluoride(eg. Water) to enhance
dental health, have far reaching consequences for other aspects of human
health. Fluoride containing toothpastes are another product in
MOVING METAL PARTS IN ELECTRIC TOOTHBRUSHES:
Readers of your journal should be made aware, that one important
difference between manual and electric toothbrushes, apart from arguments
regarding plaque removal efficacy, is that many electric toothbrushes
contain moving metal parts.
Few consumers even realize that manual toothbrushes often contain
metal parts – brush tufts are created by folding nylon bristles in half,
and then setting them in place with a small metal “plug”. This can be
readily seen with an ordinary magnifying glass, on those manual
toothbrushes that are tinted clear, as opposed to those toothbrushes that
are opaque (eg. white).
As a technician with long experience polishing alloys with abrasives,
I know that toothpaste will abrade metal. This occurs because the metal
is relatively soft (eg. stainless steel), and the abrasives in the
toothpaste are relatively hard (eg SiO2). This basic knowledge is the
foundation of a Billion dollar abrasives and mining industry. In the case
of the manual toothbrush, the metal “plugs” holding the tufts in place do
not move and so do not become abraded by the toothpaste.
In the case of the electric toothbrush, several internal moving metal
parts, together with moving plastic internal parts, are involved in
transmitting motion from the battery-powered body of the electric
toothbrush to the rotating brush head. These moving parts are exposed to
the abrasive, and so inevitably contaminate the toothpaste/abrasive slurry
with metal and plastic.
Phillip J. Colquitt, Independent Technical Advisor, New Farm,
 Mayor S. UK report recommends further research on water
fluoridation and health. BMJ 2002;325:564 ( 14 September )
 Mascarenhas . A.K. and B.A. Burt , Fluorosis risk from early
exposure to fluoride toothpaste. Community Dent Oral Epidemiol 26 (1998),
 Colquitt PJ. Do powered toothbrushes contaminate toothpaste with
Sci Total Environ. 2002 Apr 22;289(1-3):25-32.
Competing interests: No competing interests
We applaud the U.K. Medical Research Council (MRC) scientists who
discovered and reported the uncertainty of fluoridation’s health effects
(1). However, we doubt that any further research will ever solve this
contentious political debate.
Organized dentistry (within and outside of government) in the U.S.A.
has assured the American people for over 55 years that water fluoridation
is safe. They say they have the studies to prove it. But dis-interested
journalists and trusting legislators never check it out. They would find
the evidence shows the opposite.
We worry that the MRC may have revealed their bias by writing: “This
report aims to...make appropriate recommendations for research to remove
or reduce these (health) uncertainties.” Research must never start with a
Dental effects are secondary. If fluoridation imperils any child, no
government has the right to decide that the benefits outweigh the risks.
Virtually all substances can evoke allergic or intolerant reactions
is some individuals. Yet, the MRC reports that “information regarding the
allergic potential of fluoride in drinking water is sparse...There is no
information on the immunotoxicity of fluoride.” This, alone, should halt
fluoridation until the evidence proves beyond a doubt that no child can
ever be allergic to or intolerant of the fluoride chemicals that flow from
their taps into their bottles, sippy cups, oatmeal and bodies. It’s
illogical that the MRC considers this research “low priority.” Why wasn’t
this research done 55 years ago and, if not, why isn’t it top priority
The late Dr. George Waldbott, an authority on environmental diseases,
reported about his patients who became ill from drinking artificially
fluoridated water in his 1978 book “Fluoridation: The Great Dilemma.”
Painful spastic bowels, frequent nausea and vomiting, bloating of the
abdomen and persistent migraine-like headaches, and extreme thirst, were
some of the health problems reversed by avoiding fluoridated water. Too
bad today’s physicians aren’t taught to detect fluoride sensitivity.
The above symptoms are similar to the early warning signs of fluoride
toxicity reported by Dr. A. K. Susheela, an authority on fluoride’s
adverse health effects who lives and works in India where severe and
crippling fluorosis is endemic
Besides fluoride avoidance, Susheela's proven remedy for early stage
fluorosis, is a diet adequate in calcium, vitamins C, E, and other
antioxidants (2). This diet is similar to that the American Dental
Association recommends for pregnant women to assure the growth of healthy
teeth in their offspring (3).
It’s a serious omission that nutrition isn’t a recommended area to
study. It is known that consuming large amounts of simple carbohydrates,
such as chips, supermarket breads, sugary foods and beverages, not only
can increase tooth decay, but usually displaces the foods that deliver
essential nutrients required by bones and teeth. Children from low
socioeconomic groups have the most tooth decay in almost every country
and, usually, the poorest diets.
Tooth decay has declined in both fluoridated and non-fluoridated
countries. Dentists credit fluoridation or some other fluoride source for
the decline; but no studies support their belief. Americans have shown
dramatic improvement in overall health in the last 50 years, acccording to
a new U.S. Health and Human Services report(4) - one of the reasons is
healthier lifestyles. However, The affluent citizens of America enjoy
better health than do its minority and poorer citizens (5) So it is not
surprising that America’s poor and minorities also suffer the most tooth
Fluoride is neither a nutrient nor essential for teeth to resist
decay; but eating right does reduce the likelihood of cavities. Our
organization has compiled evidence that shows cavities are still very high
in fluoridated parts of the U.S. - sometimes much higher than areas with
no fluoridation (6).
We are surprised that the MRC failed to recommended studies to
correlate individual’s nutrition, fluoridation status and fluoride use
with cavities. People are responsible to eat the right foods, if they
can’t or won’t, fluoridation will do them no good. Fluoridation gives the
illusion that the government is doing something to protect teeth; but it’s
Like similar fluoridation review studies, such as the York Review,
the Irish Fluoridation Forum Report and the U.S. Surgeon General’s Report
on Oral Health , the MRC asks more questions than it answers and excludes
obviously required areas of research. We wonder if the purpose of these
review studies is merely to open up rich veins of research dollars to
benefit researchers and the universities or organizations they represent,
rather than the people who are forced to drink fluoridated water and serve
as unpaid guinea pigs and human filters for fluoride waste, without
We can’t wait for the scientists, who have assured us for decades
that fluoridation is safe, to report they are wrong. Fluoridation is a
failure and should be stopped but, if creating research funding is really
the ultimate goal, look at the diet and look for allergies!
(1) MRC “Water Fluoridation and Health,” http://www.mrc.ac.uk/pdf-
(2) NYSCOF News Release “Fluoridation Harmful, Researchers Warn”
(3) American Dental Association News Release, “Good Oral Health
Begins in the Womb”
(4) HHS News Release “HHS Issues Report Showing Dramatic Improvements
in Americans’ Health Over
Past 50 Years http://www.hhs.gov/news/press/2002pres/20020912.html
(5) National Institute of Environmental Health Sciences “Health
(6) NYSCOF News Release: “Dentists Show Fluoridation a Failure”
Competing interests: No competing interests
Following the inconclusive results of the systematic review of water
fluoridation carried out by the NHS Centre for Reviews and Dissemination
at York University, (BMJ, October 2000), the Government asked the MRC "to
determine what further research is required to strengthen the evidence
The long-awaited MRC report made yet another recommendation for
further research into dental caries.
A Pubmed search today brought up 25,344 studies on "dental caries".
Adding the word "fluoride" brought up another 4,997 studies. These 30,000+
studies by no means represent all the research carried out on tooth decay.
One might, therefore, legitimately ask how much more taxpayers' money
will be thrown into this redundant pursuit while more pressing health
issues attendant on water fluoridation are ignored.
Concern over the known complexing of aluminium and fluoride in
drinking water has caused the United States Environmental Protection
Agency and the US National Institute of Environmental Health Sciences to
request the National Toxicology Program to commission long-term drinking
water studies. These studies will address pharmacokinetics, neurotoxicity,
bone development, and reproductive and developmental toxicity. Such
testing will also investigate neurodegenerative disease in transgenic
animal models exposed to drinking water contaminants with a high health
research priority, i.e. known neurotoxicity of aluminium. The EPA and
NIEHS further acknowledge the urgent need for better understanding of
pharmacokinetics and toxicity of aluminium species occurring in drinking
Such concerns are clearly not shared by the MRC scientific panel,
which inexplicably concluded:
"Fluoride appears to reduce the bioavailability of dietary
And, how about this statement? "Fluoride in water at normal levels
can increase slightly the amount of leaching of aluminium from cooking
utensils. High concentrations of fluoride can also result in leaching of
copper from pipework. These effects are considered to be of minimal health
significance in normal circumstances."
Despite a plethora of published scientific work on adverse effects
from exposure to fluorides, the MRC is unconcerned. They stated: "Further
research on the possible effects of fluoride on immunological function,
reproduction, birth defects, intelligence, the kidney, gastrointestinal
tract and thyroid, and other suggested impacts, is considered to be of low
Although asked by the National Pure Water Association to specifically
address the fluoridation agent, (contaminated with cumulative toxicants
including arsenic, lead, beryllium, mercury, vanadium, cadmium, silicon
and radionuclides), and which has never been toxicologically tested, the
MRC ducked the issue and wrote:
"Substances added to drinking water during the fluoridation process
(including impurities of the added substances) are unlikely to add any
significant toxic potential to the water."
For decades, health officials have insisted that the fluoridation
agent dissociates completely in water, where "the fluoride ion becomes
stable and non-toxic." However, this was debunked by the US Environmental
Protection Agency which stated that ". . . metal cations [in drinking
water] compete for the fluoride ion by orders of magnitude." (Urbansky and
Schock, 2000), which was common knowledge to water treatment engineers in
The MRC curiously states: "Complexities associated with speciation,
ionic interactions etc, yield uncertainties in a number of aspects. It is
recommended that this area be kept under review."
The MRC does recommend research into TOTAL FLUORIDE EXPOSURE, but,
paradoxically, minimises the need for studies into the critical areas of
long-term health effects from TOTAL EXPOSURES TO FLUORIDES. The MRC does
not appear to comprehend that fluorides have differing toxicological
characteristics. Some fluoride species, such as aluminium fluoride, are
much more insidious toxicants than others. (Aluminium is used in water
treatment as a clarifier.).
The two chemicals permitted to dose entire populations via artificial
fluoridation schemes, (industrial grade hexafluorosilicic acid and
disodium hexafluorosilicate), Failed Formal Vote in Europe. Astonishingly,
these "dirty chemicals" were given British Standard numbers and are
described by the Drinking Water Inspectorate as "traditional chemicals"!
I would suggest that doctors, who may not prescribe any untested,
industrial grade product as a prophylactic to a patient should question
any expert body which bases its conclusions on conjecture, rather than on
science. See http://www.npwa.freeserve.co.uk/mccormick_letter.html and
Competing interests: No competing interests
The MRC report recommends research to ascertain the public's
perception of "aesthetically unacceptable dental fluorosis." Although we
have pertinent criticisms regarding some of the MRC's recommendations, we
offer here the following comments on just one of them - dental fluorosis.
In a study on convict rehabilitation at the Federal Correctional
Institution, Terminal Island, San Pedro California (1972), it was found
"The stains of endemic Dental Fluorosis can have a tremendous
psychological impact on the patient. Perhaps this might be a contributory
factor in the psychological make-up of the individual who displays anti-
social behavior. If so, it might be possible to effect change by removing
the stains. Many patients [convicts] have been pleased with the results
[bleaching of teeth], and even displayed a willingness to smile." (P.G.
Colon, Removal of Tooth Stains in Prisoner Rehabilitation, Dental Survey
Publications, Vol. 48: No 22, 1972.).
While artificial drinking water fluoridation is touted as "one of the
top ten most significant public health measures of the twentieth century",
12.5% of children in fluoridated areas develop moderate to severe Dental
Fluorosis (DF) (as seen in the photographs at
http://www.npwa.freeserve.co.uk/dental_fluorosis.html and fully referenced
in that article.).
Masking of the worst effects of DF can only be achieved through
costly cosmetic dental procedures, such as veneers, which must be repeated
every five or six years throughout the victim's life.
Therefore, despite the Department of Health's laudable goal to impact
"inequalities in dental health" via water fluoridation, the Government is
inadvertently ensuring that many of the poorest people, further
handicapped by DF, are destined to remain the most disadvantaged members
of our society.
However, Government advisers and expert health professionals
zealously promote water fluoridation KNOWING that a large percentage of
the population will develop DF; KNOWING that DF has severe psychological
impacts on many of its victims, and KNOWING that people with "dirty teeth"
are very likely to experience discrimination in the vital areas of
employment and personal relationships.
The "experts" regard DF as 'a classic public health trade-off' for a
(highly questionable) reduction in cavities. The NHS CRD reported that 48%
of people living in fluoridated areas have DF and 12.5% have aesthetically
unacceptable DF. So, which individuals will draw the short straws in the
great Dental Fluorosis Lottery?
In a revealing 1999 study, first year dental students were surveyed,
with the aid of photographs of mild dental fluorosis, to ascertain their
perception of the condition. The study found a heavily negative
perception. A follow-up study in 2002 surveyed students in their fourth
year of dental school. Again, they were shown photographs of mild dental
fluorosis. This time, their perception was much more positive!
This raises the question of who will conduct new research to
determine the public's perception of DF - dentists, who have been schooled
to view it positively? We suggest that this work should be done by
psychologists, who are qualified to determine the victims' self-perception
and ascertain how DF impacts their lives.
Meanwhile, those who can't afford to pay the ransom for their stolen
smiles must remain the forgotten victims of what must surely be the most
disgraceful 'classic public health trade-off' in history: artificial water
National Pure Water Association.
Competing interests: No competing interests
The Medical Research Council needs to examine another potential
hazard arising from the fluoridation of public supplies, where the process
uses the silicofluorides rather than sodium fluoride.
Some areas of the country, and perhaps some parts of all areas, still
have lead pipes carrying the domestic water supply. The silicofluorides
are the by-products of the phosphate fertiliser industry. In the
manufacture of this kind of fertiliser, phosphorus is obtained from
phosphate rock, which has to be broken down with sulphuric acid. Fluorine
occurs naturally in combination with the phosphates. In these two facts
lie the keys to the presence of lead in the silicofluorides.
Some sulphuric acid is prepared by the lead chamber process. In this
process, purification is carried out only to the extent of removing
substances that could clog the machinery. Of the common metals, only lead
is resistant to cold sulphuric acid in concentrations up to 100%. But in
hot acid the resistance is up to about 70%. The lead chamber type uses
heat (about 600C) and isn't cooled during the process. This allows a
certain amount of lead to be leached during the procedure.
Thus fluoridation can actually increase the lead content of water
above that already possible from the water being carried in lead pipes. A
study published in 1999, in the International Journal of Environmental
Studies, and led by Roger Masters, Emeritus professor of government at
Dartmouth,(USA) describes a factor that is correlated with higher lead
levels in children. Analysing a survey of over 280,000 Massachusetts
children, the investigators found that silicofluorides are associated with
an increase in children's absorption of lead.
In their analysis, the investigators found that levels of lead in
children's blood was significantly higher in Massachusetts communities
using the silicofluorides, fluosilicic acid and sodium silicofluoride than
in towns where water is treated with sodium fluoride or not fluoridated at
all. Compared to a matched group of 30 towns that do not use
silicofluorides, children in 30 communities that use these chemicals were
over twice as likely to have over 10ug/dL of blood lead.
Competing interests: No competing interests