Friday, May 10, 2002
By Steven Milloy
Junk science has united quite the political odd
couple - Reps. Diane Watson, D-Calif., and Dan
Burton, R-Ind. They recently co-sponsored a bill to end the use of mercury
in dental fillings.
The
bill would: ban dental amalgam containing mercury from children under 18
and pregnant and lactating women; require dentists to warn patients
that mercury is "highly toxic" and poses "health
risks"; and phase out mercury amalgam by 2007.
Rep.
Watson, a Congressional Black Caucus member from Watts who claims to be
"chemically sensitive," has targeted mercury-containing dental
amalgam since CBS’ 60 Minutes spotlighted the scare in December
1990.
Rep.
Burton, the anti-Clinton lightning rod, only recently converted to
anti-mercury-ism. Burton blames thimerosal, a mercury-based preservative
used in vaccines, for causing his grandson’s autism.
Also
in on the mercury scare are - who else - unscrupulous personal injury
lawyers. Class action lawsuits have been filed against the American Dental
Association and the California and Maryland state dental associations
seeking the return of monies paid for mercury-containing fillings - the
great majority of fillings ever done.
Lawsuits
alleging thimerosal causes autism also have been filed against vaccine
manufacturers.
As
to mercury in dental fillings, the lawsuits are among the best evidence
that mercury in amalgam is harmless. Though the complaints allege that
mercury-containing amalgam is harmful, they contain no specific
allegations of harm to anyone.
This
is hardly surprising.
Mercury
has been a major ingredient of dental amalgam (35-42 percent) for more
than 150 years. No other filling material has been proven to be safer,
more durable and more cost-effective.
The
National Institutes of Health reports only about 100 documented cases of allergy
to mercury mentioned in the scientific literature since 1906 - despite billions
of uses of mercury amalgam and tens of millions more of thimerosal-containing
vaccines.
Mercury
can have toxic effects on the nervous system - but only at
sufficiently high exposures. As is the basic rule in toxicology, it is the
dose that makes the poison. Paracelsus, the father of this principle,
successfully used this principle - and mercury - to treat
syphilis in the 16th century.
Fillings
containing mercury typically emit about 1-3 millionths of a gram
(micrograms) per day. An individual might be unavoidably exposed to
another 5-6 micrograms of mercury through food, water and air. Such
exposures are well below the World Health Organization’s
"acceptable daily intake" for mercury, about 30 micrograms per
day.
Keep
in mind that the ADI is not a "safety" level; it’s a level set
by regulatory agencies that is anywhere from tens to thousands of times
below dose levels reported to cause biological effects in animal
experiments. The ADI is set well below effect levels to provide a wide
margin of safety for potential exposures.
Amalgam
expert Dr. Rod Mackert says even the most sensitive individual would need
about 450 fillings before exhibiting even slight symptoms of mercury
toxicity.
Finally,
even the hyper-cautious Food and Drug Administration concluded in March,
2002, that "No valid scientific evidence has ever shown that amalgams
cause harm to patients with dental restorations, except in the rare case
of allergy."
But
why let a lack of factual support get in the way of a feel-good law and a
chance at the lawsuit jackpot?
Rep.
Burton’s anti-mercury rationale and the vaccine-related lawsuits are
similarly deficient.
It’s
true many children may have been exposed to relatively high levels of
mercury through vaccines preserved with thimerosal. Even so, there’s no
evidence these exposures harmed any child - a point reaffirmed by FDA
researchers in a May 2001 article in the journal Pediatrics.
Moreover,
no one knows what causes autism. A National Institutes of Health working
group concluded in 1995 that autism likely was mostly genetic in origin.
No evidence indicates that late-pregnancy or after-birth events -
including extensively studied mass mercury poisonings - are associated
with autism.
Burton’s
desperate rush to blame an after-birth event for causing autism isn’t
unusual.
Autistic
behavior becomes apparent as children progress from saying a few words to
generating more complex language, at ages of 16-36 months. Parents whose
children "turn" autistic often erroneously associate the onset
of autistic behavior with some contemporaneous event such as vaccination.
But
public alarm about vaccine safety can be a public health problem.
Outbreaks of measles, for example, occurred in the U.K. and Ireland where
many worried parents shunned the measles-mumps-rubella (MMR) vaccine.
Instead
of filling our minds with fear and the U.S. Code with needless laws (and
our courtrooms with meritless lawsuits), Reps. Watson and Burton and
the personal injury lawyers should fill themselves, as appropriate,
with facts and scruples.
Steven Milloy is the publisher of
JunkScience.com , an adjunct scholar at the Cato Institute
and the author of Junk Science Judo: Self-defense Against Health Scares
and Scams (Cato Institute, 2001).
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