.
Dr. William Marcus' May 1 Memo on NTP Bioassay on Fluoride
UNITED STATES ENVIRONMENTAL
PROTECTION AGENCY
WASHINGTON. D.C. 20460
OFFICE OF WATER
MEMORANDUM
DATE: May 1, 1990
SUBJECT: Fluoride Conference to Review the NTP Draft Fluoride
Report
FROM: Wm L. Marcus, Ph.D., Senior Science Advisor, Criteria
& Standards Division, ODW (WH-550D)
TO: Alan B. Hais, Acting Director, Criteria & Standards
Division, ODW (WH-550D)
The conference was held in RTP at the NIEHS headquarters on April 26, 1990.
The subject of the conference was a peer review of the NTP
draft report on the toxicology and carcinogenesis studies of Sodium
Fluoride in F344/N Rats and B6C3F Mice (Drinking Water Studies) NTP Report
Number 393. Dr. Robert Scala was to chair this meeting but was unable to
attend because of ill health. Dr. Michael Gallo appointed acting Chairperson.
One of the attenders seated with the panel members was David Rall, Ph.D.,
M.D., Director of NIEHS. Dr. Rall took an extremely active interest in the
proceedings and remained seated for the entire proceedings with only two
minor interruptions.
The most disturbing part of the report was the continual reference to the
historical controls as having the same or higher cancers as the test groups.
On pages 89 - 90 of the report starting with the last paragraph the authors
state the following:
An important consideration which
limits the usefulness of the historical control data base in the current
studies is that the diet used in all other NTP studies had not been closely
monitored for fluoride content. Fluoride concentrations in typical batches
of NHI-07 diet range between 28 and 47 ppm (.7 and 1.2 mg/kg/day)(Rao and
Knapka (1), 1987). Assuming a minimum bioavailability of 60% (Tests show
66% absorption page I-18), the historical database animals actually constitute
a group receiving sufficient fluoride to place them between the low- and
mid-concentration group in the current (the studies reviewed at RTP at the
conference). The fact that this fluoride is available for absorption from
the standard diet is supported by the levels of fluoride found in the bones
of animals maintained on this diet in the six months studies (Appendix I).
(The levels in the bones of the rats on the standard NHI chow was ten [10]
times the levels of those fed the semisynthetic diet and deionized water,
0.922 vs 0.0901). If the fluoride [is] in fact influencing the "spontaneous
" or background incidence of osteosarcoma in male rats, comparisons
with those in the historical database maybe misleading. This forces an even
greater reliance on the within-study comparisons, ie., the incidences of
the dosed groups compared with the concurrent control, in the interpretation
of the results of the sodium fluoride studies.
[italics in memo]
When I plotted a bar graph of osteosarcoma
in male rats and placed the historical controls on the graph 0.6% is just
where expected. This helps demonstrate a relationship between osteosarcoma
and fluoride. The purpose of such graphs is to predict occurrence. Since
the historical controls comprise some 6,000 animals, this data point is
extremely significant compared to the other three. Osteosarcoma is an extremely
rare animal tumor and may be the result of the variable high fluoride content
in the feed. In order to demonstrate this, all that need be done is require
that the fluoride content of animal chow be lowered dramatically and that
fluoride be removed from the water given to the animals under study.
The dose of fluoride to which the concurrent controls were exposed is 0.2
mg/kg/day. A 70 kg man who drinks 2 liters daily is exposed to 0.03 mg/kg/day.
The "control" animals were exposed to an amount of fluoride six
to seven (6-7 X) greater. Lois Gold, Ph.D. of the review panel concluded
that, "this group of animals therefore, can hardly be termed a control
group. It can best be described as a lowest dosed group." This is an
important consideration because as the document reports on page 9, the levels
of fluoride in bone are linearly dependent upon dose and length of exposure
("depends upon total intake") in people. The level of fluoride
in ashed samples of bone of 20-30 year old people is 200 - 800 mg/kg compared
to 70 to 80 year old people of 1,000 - 2.500 mg/kg. In the document, the
authors cited Zipkin (2) who
reported on bone fluoride concentrations in four groups of individuals with
average ages of 56 to 76 who lived in areas with fluoride concentrations
in drinking water of 0. 1, 1, 2.6, or 4 ppm The relationship to bone fluoride
concentrations and water fluoride content was linear; bone fluoride ranged
from about 800 to 7,000 ppm ash with increasing water fluoride."
In the animal studies the levels of fluoride (Appendix I) found in the bones
of the animals were the same as or lower than those found in people. The
highest dosed level of rats had lower levels of fluoride in their bones
(5,470 ppm) compared to people (7,000 ppm) at the MCL of 4 ppm. This can
be interpreted as people who ingest drinking water at the MCL have 1.3 times
more fluoride in their bones than male rats who get osteosarcoma This is
the first time in my memory that animals have lower concentrations of the
carcinogen at the sight of adverse effect than do humans. An important toxicologic
consideration is that a toxic substance stores at the same place it exerts
it toxic activity. This is true of benzene and now for fluoride. Fluoride
however, is at twice the concentration in human bones compared to benzene
which is 10 to 100 [times] greater in animal marrow. This portends a very
serious problem. One would expect to be able to discern a carcinogenic effect
in the exposed population when compared to the unexposed population especially
if data exist on the populations before fluoridation.
Yiamouyiannis and Burk published epidemiology studies that have since been
revised twice (3), by Burk (former head of the Cytochemistry section at
NIH). In these extensively peer reviewed papers, the authors found that
about 10,000 deaths a year are attributable to fluoride water treatment.
The U.S. Public Health Service (U.S.PHS) criticized the original studies
by erroneously asserting that the results reported by the authors were a
result of changes in the age, race and sex composition of the sample. The
U.S.PHS made mathematical errors and did not include 90% of the data. U.S.PHS
method of analysis when applied to the database, confirmed that 10,000 excess
cancer deaths yearly were linked to fluoridation of water supplies. This
evidence has been tested most recently in the Pennsylvania Courts and found
scientifically sound after careful scrutiny.
There were three different short term in vitro tests performed on fluoride
and all these tests proved fluoride to be mutagenic. An Ames test was performed
and reported to be negative. Bruce Ames, in a letter to Arthur Upton introduced
in the Congressional Record, stated that his test system was inappropriate
for fluoride testing based on a number of technical considerations. EPA's
own guidelines require that in vitro tests be taken into consideration when
found positive. In this case, the mutagenicity of fluoride supports the
conclusion that fluoride is a probable human carcinogen.
Melvin Reuber, M.D, a board certified pathologist and former consultant
to EPA and part time EPA employee, reviewed some of pathology slides and
the Battelle report. Dr. Reuber has had his pathologic diagnoses questioned
several times in the past. When an independent board together with Dr. Reuber
went over the Slides his opinion was always upheld. He first published the
work that identified hepatocholangiocarcinoma as a pathologic entity. The
report changed Battelle's board certified veterinary pathologists diagnoses
from hepatocholangiocarcinoma to hepatoblastoma and finally to hepatocarcinoma.
Dr. Reuber reviewed the pathology slides and stated that these lesions are
indeed hepatocholangiocarcinoma. Because Dr. Reuber first identified and
published his findings on this tumor, I trust his opinion in this matter.
These tumors are extremely rare. Dr. Reuber's diagnoses would make the liver
cancers significant because of their rarity. This changes the equivocal
finding of the board to at least some evidence or clear evidence of carcinogenicity.
In addition, the oral changes in the report were down-graded from dysplasia
and metaplasia to degeneration. Dr. Reuber said that this. change should
also be reviewed. The report also down-graded adrenal pheochromocytomas
and tumors to hyperplasia. This needs to be reviewed by an independent board.
The other liver carcinomas were down-graded to foci by artificially defining
a need for 75% compression in the tumor before it was no longer a foci.
Using this changed definition carcinomas were down-graded to adenomas and
adenomas downgraded to eosinophilic foci. In almost all instances, the Battelle
board certified pathologists' findings were down-graded. It is my suggestion
that a board independent of NIEHS should be assembled by ODW consisting
of human pathologists (for their experience in diagnosing osteosarcoma),
the Battelle pathologist (to defend his original diagnoses), Dr. Melvin
Reuber, Dr. Thomas Squires and two other well known independent board-certified
animal pathologists. The charge to this board is to meet as a body, review
the slides, agree on a pathologic diagnoses and prepare a report to be submitted
to ODW for incorporation in our docket for the fluoride regulation.
The report talks about the efficacy of fluoride and tooth decay. Since the
studies were performed to determine the carcinogenicity of fluoride this
should not have been addressed. There appear to be at least four different
publications from the U.S., Canada, and New Zealand that have reported similar
or lower tooth decay rates in nonfluoridated areas as compared to fluoridated
areas (4,5,6,7). Therefore, the entire question of the efficacy of fluoridation
based on extensive and multiple studies has been called into question. Our
job is to set safe levels for fluoride in drinking water based on the scientific
evidence.
The problem with this meeting was the inability of independent reviewers
to get to see the slides prior to the meeting. We must perform our own scientific
review of the slides and write our conclusions for use in the development
of the revised fluoride regulation.
(1) Roa, G.N., and Knappa, J.J. 1987. Contaminant
and nutrient concentrations of natural ingredient rat and mouse diet used
in chemical toxicology studies. Fundam. Appl. Toxicol.
9, 329-338.
(2) Zipkin, L., McClure, F.J., Leone, H.C., and
Lee, W.A. 1958. Fluoride deposition in human bones after prolonged ingestion
of fluoride in drinking water. Public Health Rep. 73,
732-740.
(3) Graham, J.R., Burk, O., and Morin, P. 1987.
A current restatement and continuing reappraisal concerning demographic
variables in American time-trend studies an water
fluoridation and human cancer. Proc Pennsylvania Academy of Sci. 61:138-146.
(4) Colquhoun, J. 1987. Comm. Health Studies. 11:85.
(5) Gray, a. 1987. J. Canadian Dental Assoc. 53:763.
(6) Hildebolt, C.F. et al. 1989. Amer J, Physiol. Anthropol. 78:79-92.
(7) Diesendorf, M. 1986. Nature. 321:125.