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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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