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Fluoridation Side Effects |
Fluoride, Cancer |
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Does water fluoridation
have negative side effects? (Note by Andrew Saul:
Fluoridation of water owes its continued existence more to politics than to
science. If safety and effectiveness are truly considered, fluoride
would be questionable even as a prescription drug. But to freely add it
to public water supplies, often without any public vote whatsoever, is far
beyond questionable. Mr. Meiers' discussion of the dangers of fluoride
is important reading.) The National Health
Service (NHS) Centre for Reviews and Dissemination at the This is not a new
experience. Fears of undesired effects of the controversial "public
health measure" have never been taken serious by its promoters. Even
though animal experimentation on fluoride and cancer, performed long before
any fluoridation experiment was started in the United States [Meiers 1984,
1986], could have given reason for concern, investigations into possible
fluoride effects on human cancer victims were not initiated by promoters of
the measure prior to any fluoridation efforts nor in the course of the first
experimental trials, but by opponents whose charges posed a threat to the
continuing supply of public funds and thus necessitated appropriate replies
[American Dental Association 1952]. For example, at government hearings in
1952, Relative to the city of
Grand Rapids, fluoridated since January 1945, Perkins wrote: It was these claims that
prompted Swanberg [1953] to evaluate the cancer data of "The death rate from
cancer in The Likewise, the Several studies published
after the 1956 Newburgh-Kingston "final report" focused on possible
effects of natural fluoride waters on the incidence or mortality of cancer
and revealed some major shortcomings. They were essentially static (comparing
data of just one year) as opposed to the time-trend analyses quoted above.
Further-more, the concentration of natural fluoride varies (even in one and
the same water supply), and so does the num-ber of registered water supplies
within each municipality [Heasman and Martin 1962; Glattre and Wiese 1979].
Therefore, it seems to make no sense to compare areas with a water fluoride
level of 0.06-0.10 mg/l to areas with 0.11-0.5 mg/l, as Glattre and Wiese do,
nor to arrange fluoride cities into groups based on a difference of one
hundredth mg/l (i.e. 0,5-0,99 vs.1 mg/l and more) as Kinlen [1974,
1975] does. Where more than one water source supplies a local authority some
authors calculated "weighted means" [Chilvers and "The method for
obtaining the ratios shown in table I was to calculate for each sex and each
age group the number of cases that would be expected in the population in
question in each fluoride category if the total number of cases in all areas
combined was distributed uniformly." That means, he pooled the groups to
calculate his "expected" cancer deaths and thus used a reference
population partly exposed to the variable to be tested! While the In case fluoride
increases the number of deaths, inclusion of exposed people in the reference
population would raise the number of (speculative) "expected"
deaths in the groups to be examined (depending on population structure). As
Standardized Mortality Ratios (SMR´s) are calculated by dividing the number
of observed cancer deaths per 100,000 people (O) by the number of
"expected" cancer deaths per 100,000 people (E), the SMR (O:E)
becomes the lower the higher the "expected" (E) rate. This kind of
SMR calculation applied in time-trend studies to populations of different
size and structure (fluoridated vs. non-fluoridated cities) using a shifting
refer-ence population (USA 1950, 1960, 1970 as the standard for the
corresponding census years) creates the artifact of decreasing cancer death
rates in fluoridated cities. An example: In a hypothetical
population with no change both in population structure and the number of
cancer deaths during 1950 to 1970, applying U. S. data in 1950 by age, gender
and race to calculate the number of deaths expected for 1950 in that
population, and likewise U.S. data in 1960 and 1970 for those respective
years, will result in an increasing number of expected deaths in the time
span 1950 to 1970, since cancer death rates rose in the U.S. during that
time. As the number of deaths expected in the hypothetical population will
increase, i.e. "E" becomes higher, the O:E ratio (SMR) becomes
lower. Thus one will be able to show that the cancer death rates decreased in
that population (while, as presupposed above, nothing happened at all with
the actual rates). What a large increase in cancer death rates would be
required just to balance the misleading SMR calcu-lations for the
hypothetical population if it were exposed to a carcinogen to be evaluated! This is why the
re-analyses by Smith [1980] as well as Kinlen and Doll [1981] of the
Yiamouyiannis and Burk [1977] study on the fluoridation-cancer link are
useless. Of these, the Smith paper got a high ranking according to the As the Grand Rapids and
Newburgh/Kingston data show, there are large fluctuations of cancer death
rates over time in individual cities so that it isn´t appropriate to select
just two data points for statistical evaluation, but the best approach would
be to make a linear regression analysis to compare rates before and after
fluoridation started. As differences might be small it seems to be a good
idea to pool the data of several fluoridated cities and to compare them to a
set of non-fluoridated ones. In 1975, Yiamouyiannis
and Burk reported to the U.S. Congress that a set of 20 U.S. central cities
had almost identical cancer mortality rates (cancer deaths per 100,000 people
per year) between 1940 and 1950, but that since fluoridation started (in
1952-1956) in a group of ten of these cities their cancer death rate
increased faster than that of the ten cities remaining non-fluoridated (Fig.
3). The study was later published in the Journal "Fluoride"
[Yiamouyiannis and Burk 1977] and caused quite a stir. Early in 1976, a
representative of the National Cancer Institute (NCI) claimed in a letter to
Congressman Delaney that the NCI´s re-analysis showed that the increase was
entirely due to changes in the age, race and sex structure of the population
in question [Fredrickson 1976]. While refusing congressional requests for
detailed data (weighted or unweighted rates used? Which reference population?
etc.), the NCI clandestinely has passed this data on to other scientists
[Yiamouyiannis 1977] who reported them as their "independent analysis"
[Doll and Kinlen 1977; However, the main point
of disagreement between the statisticians is that whereas Burk and his group
derived putative "observed Cancer Death Rates" (CDRo) by linear
regression analysis of all available and pertinent data, i.e. the crude CDR´s
characterizing the observation period of 1953 to 1968, and extrapolation to
1950 and 1970, other investigators have taken reported or pericensal CDRo
figures for 1950 and 1970. "If, as they say, only the censal or
pericensal data for 1950 or 1970 ought to be taken into account, the
association between fluoridation and cancer is wiped away by adjustment. If
instead, as we insist, the intermediate data for 1953 through 1968 must be
used, a large association remains, notwithstanding adjustment" [Graham
et al. 1987]. Neither regression analysis of cancer death rates
[Mahoney et al. 1991] nor calculation of intercensal population by
interpolation of data acquired in census years [Cohn 1992] seem to be
unacceptable methods. Furthermore, a look at age-specific cancer mortality
data for the twenty cities, unfortunately only available for 1970, indicates
a higher cancer mor-tality at an earlier age in the fluoridated group (Fig.
4). The difference is obvious in these large populations even though people
in non-fluoridated cities are exposed to fluoride from sources other than
drinking water (tablets, drops, mouthwashes, topical applications, canned
foods prepared in fluoridated cities, etc.). While epidemiologists
hitherto essentially looked for evidence in human populations of a per se
carcinogenic effect of fluoride, substantiated by more recent in-vitro
experiments [Tsutsui et al. 1984; Jones et al. 1988; Lasne et al. 1988], the
question raised by Perkins in 1952 relative to the promoter effects of
fluorides has still not been addressed, neither by health officials in
general nor by the York team. Humans today are exposed to not one but many
different carcinogenic agents (including chemicals, viruses, ionizing
radiation) which interact in very intri-cate ways. Fluoride is known to
inhibit some enzymes and to activate others. Fluoride inhibits the enzymatic
deacetylation of N-Hydroxy-Acetylaminofluorene [ According to a WHO
scientific group "the occurrence of tumors earlier than in the controls,
without increased incidence" is among the types of responses "used
to classify chemicals as carcinogens" [WHO 1969]. Enhancing effects are
also apparent from some life table data published in the National Toxicology
Program carcinogenicity test of sodium fluoride [NTP 1990]. This test had
been requested by the U.S. Congress during hearings in 1977. Back then, NCI
representative Kraybill [1977] presented a list of publications which, he
al-leged, had already shown that sodium fluoride has no carcinogenic
activity. However, not a single one of the publications on his list had
anything to do with fluoride and cancer. Anyway, the start of the
carcinogenicity test requested by Congress was announced four years later
[Whitmire 1981]. After another four years, a first result was declared
inadequate because the low fluoride semisynthetic diet "was deficient in
several vitamins and minerals" [NTP 1985]. Another two-year study was
scheduled to begin in October 1985. The report, released in 1990, focused on
the occurrence of a rare form of cancer, osteosarcoma, in several of the male
(but not the fe-male) dosed rats used in the study [NTP 1990]. This evidence
of carcinogenicity was downgraded to be "equivocal". Nevertheless, a few
epidemiological studies addressed a possible influence of water fluoridation
on the incidence of osteosarcoma in humans. It occurs in less than one in
100,000 people or about 0.1 percent of all reported can-cers, and therefore
it would be hard to detect small increases in risk (on the order of five to
ten percent) [USPHS 1991]. Examinations in a very limited number of
afflicted people led to conflicting results. The study designs (e.g.
exclusion of people formerly exposed to some radiation) reveal that still the
search for a per se carcinogenic effect of fluoride was in the foreground.
There seems to be agreement that osteosarcoma incidence in the In summary, the References: American Dental
Association (1952): " Cohn P.D. (1992): "A
brief report on the association of drinking water fluoridation and the
incidence of osteosarcoma among young males"; New Jersey Department of
Health, Nov. 8 Doll R., Kinlen L.
(1977): "Fluoridation of water and cancer mortality in the Dophuoc H., Bompart G.,
Bourbon P. (1981): "Effects of hydrogen fluoride on benzo(a)pyrene and
dimethylnitrosamine metabolism in rats"; Naturwiss. 68: 621 Dophuoc H., Bompart G.,
Bourbon P., Bouteille L. (1983): "Action du fluorure sur le métabolisme
hépatique de la diméthyl-nitrosamine et du benzo(a)pyrène chez le rat";
Toxicol. Eur. Res. 5: 31 Fredrickson D.S. (1976):
Letter to Hon. J. J. Delaney, Feb. 6, 1976; reproduced in: The National
Cancer Program, Part II: Fluoridation of Public Drinking Water ,
Hearings before a subcommittee of the committee on government operations,
House of Representatives, 95th Congress, 1st session, Sept. 21 and Oct. 12,
1977; Washington, p. 356 Graham J.R., Burk D.,
Morin P. (1987): "A current restatement and continuing reappraisal
concerning demographic variables in American time-trend studies on water fluoridation
and human cancer"; Proc. Pennsylv. Acad. Sci. 61:138 Irving C.C. (1966):
"Enzymatic deacetylation of N-Hydroxy-2-Acetylaminofluorene by liver
microsomes"; Cancer Res. 26:1390 Jones Kinlen L. (1974):
"Cancer incidence in relation to fluoride level in water supplies";
Commun. Health 6:69 Kinlen L. (1975):
"Cancer incidence in relation to fluoride level in water supplies";
Brit. Dent. J. 138:221 Kinlen L., Doll R.
(1977): "Cancer and Fluoride"; The Lancet II, 1039 Kraybill H. (1977):
"The National Cancer Program, Part II: Fluoridation of Public Drinking
Water, Hearings before a sub-committee of the committee on government
operations, House of Representatives, 95th Congress, 1st session, Sept. 21
and Oct. 12, 1977; Washington , Government Printing Office, p. 239 Lasne C., Lu Y.P.,
Chouroulinkov L.(1988):"Transforming activities of sodium fluoride in
cultured Syrian Hamster Embryo and BALB/3T3 cells"; Cell Biol. Toxicol.
4:311 Mahoney M.C., Nasca P.C.,
Burnett W.S., Melius J.M. (1991): "Bone cancer incidence rates in McDonagh M., Whiting P.,
Bradley M., Cooper J., Sutton A., Chestnutt I., Misso K., Wilson P., Treasure
E., Kleijnen J. (2000): "A systematic review of public water
fluoridation", NHS Centre for Reviews and Dissemination, University of
York Meiers P. (1984):
"Zur Toxizität von Fluorverbindungen mit besonderer Berücksichtigung der
Onkogenese"; Verlag für Medizin, Meiers P. (1986):
"Experimente ueber Fluoridwirkungen im Krebsgeschehen",
Erfahrungsheilkunde No. 6:424-432 NTP (1985): "Statement
to accompany preliminary data tables from the NTP two-year sodium fluoride
study performed Dec. 1981 to Dec. 1983 – prepared July 29, 1985" NTP (1990):
"Toxicology and carcinogenesis studies of sodium fluoride (CAS No.
7681-49-4) in F344/N rats and B6C3F1 mice (Drinking Water Studies)",
National Toxicology Program, Technical Report Series 393, U.S. Department of
Health and Human Services Oldham P.D., Newell D.J.
(1979): "Letter to the editors"; Appl. Statist. 28: 184 Perkins C.E. (1952):
"The truth about water fluoridation"; published by the Fluoridation
Educational Society, Schepers G.W.H. (1961):
"Neoplasia experimentally induced by beryllium compounds"; Progr.
Exp. Tumor Res. 2:203 Schlesinger E.R., Overton
D.E., Riverhead L.I., Chase H.C., Cantwell K.T. (1956):
"Newburgh-Kingston caries-fluorine study. XIII. Pediatric findings after
ten years"; J. Am. Dent. Assoc. 52:296 Schuld A. (2000):
"UK Review", http://www.bruha.com/fluoride/html/uk_review.html
(Oct. 2000) Smith A. H. (1980):
"An examination of the relationship between fluoridation of water and
cancer mortality in 20 large Swanberg H. (1953):
"Fluoridation of water and its relation to cancer", Tannenbaum A.,
Silverstone H. (1949): "Effect of low environmental temperature,
dinitrophenol, or sodium fluoride on the formation of tumors in mice",
Cancer Res. 9:403 Taylor A. (1952):
Testimony, Feb. 19, "Chemicals in Food and Cosmetics", Hearings
before the House Select Committee to investigate the use of chemicals in
foods and cosmetics, House of Representatives, 82nd Congress, 2nd session,
pursuant to H. Res. 74 and H. Res. 447, Part 3, U. S. Government Printing
Office Taylor A. (1954):
"Sodium fluoride in the drinking water of mice", Dental Digest
60:170 Taylor A., Taylor N.C.
(1965): "Effect of sodium fluoride on tumor growth", Proc. Soc.
Exp. Biol. Med. 119:252 Tsutsui T., Suzuki N.,
Ohmori M.(1984): "Sodium fluoride-induced morphological and neoplastic
transformation, chromo-some aberrations, sister chromatid exchanges, and
unscheduled DNA synthesis in cultured Syrian Hamster Embryo cells";
Cancer Res. 44:938 USPHS (1991):
"Review of fluoride. Benefits and Risks. Report of the ad hoc
subcommittee on fluoride of the Committee to coordinate environmental health
and related programs", Department of Health and Human Services, U. S.
Public Health Service; (Study of Hoover et al. (NCI) in Appendix F) Wagner H. J. (1981):
"Der Einfluß von Fluorid, Licht und 3,4-Benzpyren auf die Tumorinduktion
bei NMRI-Mäusen"; Inau-gural Dissertation, Erlangen-Nürnberg Whitmire C.E. (1981) :
"Carcinogenesis bioassay of sodium fluoride"; Tox-Tips 56:56-19 WHO (1969) :
"Principles for the testing and evaluation of drugs for carcinogenicity.
Report of a WHO Scientific Group", World Health Organization, Technical
Report Series, No. 426, Yiamouyiannis J., Burk D.
(1975): "Cancer from our drinking water?", Congressional Record,
Proceedings and debates of the 94th Congress, 1st session Yiamouyiannis J. (1977):
"The National Cancer Program, Part II: Fluoridation of Public Drinking
Water", Hearings before a subcommittee of the committee on government
operations, House of Representatives, 95th Congress, 1st session, Sept. 21
and Oct. 12, 1977; Washington, Government Printing Office Yiamouyiannis J., Burk D.
(1977): "Fluoridation and cancer. Age dependence of cancer mortality
related to artificial fluori-dation"; Fluoride 10:101 Ziegelbecker R. (1987):
"Zur Frage eines Zusammenhangs zwischen Trinkwasserfluoridierung, Krebs
und Leberzirrhose"; gwf – Wasser – Abwasser 128: 111 Reprinted with permission of the
author, Peter Meiers. Andrew Saul is the author of the books FIRE
YOUR DOCTOR! How to be Independently Healthy (reader reviews at
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) and DOCTOR YOURSELF: Natural Healing that Works. (reviewed at http://www.doctoryourself.com/saulbooks.html
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