The New York Times
April 27, 1990
Weak Link on Fluoride and Bone Cancer is Backed
by Malcolm W. Browne
Special to the Times
RESEARCH TRIANGLE PARK, N.C., April 26 - A panel of scientific
experts today endorsed the findings of a Federal investigation showing
that a compound widely used to fluoridate public water supplies
may cause bone cancer in male rats.
The panel found that the evidence inconclusively demonstrated a
weak association between fluoride consumption and the bone cancer
in male rats.
Federally sponsored scientists who conducted the study say the
finding does not in itself imply a hazard to humans from drinking
fluoridated water. But opponents of fluoridation who attended the
meeting today argued that the evidence was now strong enough that
fluoridation should be halted. Roughly half of all Americans drink
fluoridated water. A representative of the American Dental Association
attending the meeting condemned the report of the fluoride study
as misleading. Another proponent of fluoridation threatened the
scientists with legal action if they retained the wording of their
report.
A 2-Year Study
The public meeting conducted by 13 independent scientists here
today set the official seal on results of a two-year investigation
by the National Toxicology Program, a branch of the Public Health
Service. Mice and rats of both sexes were fed varying amounts of
sodium fluoride at doses up to 20 times those human beings might
encounter in drinking water. The animals were killed and very carefully
examined.
The most striking result was that some male rats in the study
contracted osteosarcoma, or bone cancer, significantly more often
when they received increasingly high levels of sodium fluoride.
But neither female rats nor any of the mice showed any increase
in bone cancer.
The National Toxicology Board therefore said, ''The current findings
are inconclusive, but are weakly supportive of an association between
sodium fluoride administration and the occurrence of osteosarcomas
in male rats.''
This was unanimously adopted by the panel of independent scientific
experts convened to give the report ''peer review.'' Several panelists
urged that in view of the evidence, a more comprehensive investigation
should be begun.
Dr. John R. Bucher, the National Toxicology Program scientist who
directed the study, said his agency could perform a more comprehensive
investigation. ''But we have no mandate or plans to do so at present,''
he said.
Dr. Michael A. Gallo, an environmental scientist who acted as
chairman of the meeting today, reminded participants that its purpose
was not to decide on the possible carcinogenicity of fluorides to
humans, or on the advisability of fluoridating water.
Undertone of Tension
''At this level,'' he told a reporter, ''scientists are simply
trying to assess possible hazards. Other scientists would then examine
possible human exposure to that hazard to determine risk. Finally,
risk must be weighed against potential benefit.''
But despite the cautious tone of most of the speakers at the meeting,
there was an undertone of tension that occasionally found voice.
''
We're all very much aware that the chemical we're considering here
is no ordinary one, but is the substance in nearly everyone's drinking
water,'' said Dr. Ellen K. Silbergeld of the University of Maryland
Medical School. ''But as scientists we must discuss sodium fluoride
with no more emotion than we would when considering the toxicity
of any other chemical.''
Among the public witnesses permitted to speak was Dr. John A.
Yiamouyiannis of Delaware, Ohio, a scientist who is a leading opponent
of water fluoridation. ''The evidence brought to light in the National
Toxicology Program report coupled with earlier studies is clear,''
he said. ''Sodium fluoride should now be declared a Class A carcinogen.''
Class A is the designation for dangerous substances.
A study conducted 13 years by Dr. Yiamouyannis and Dr. Dean Burk,
former head of the cellular chemistry section of the National Cancer
Institute, concluded that 10,000 excess cancer deaths occur each
year in the United States because of water fluoridation. The Yiamouyannis-Burk
investigation caused so much public concern that Congress ordered
the investigation that resulted in the report ratified today.
Conclusions Are Assailed
Several other speakers appearing as witnesses before the panel
of scientists took strong exception to the report. Speaking for
the American Dental Association, Dr. John W. Stamm declared that
the conclusions of the National Toxicology Program were not justified,
since animal studies were not reliable indicators of effects on
humans.
|