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Mercury used in dental fillings, some vaccines
By JOHN KRIST
Scripps-McClatchy Western Service
May 18, 2001
VENTURA, Calif. - In their effort to reduce the
health threat posed by mercury, regulatory agencies and public-health
officials have focused on reducing industrial emissions and warning
consumers away from contaminated fish. But not all human exposure to
mercury is inadvertent. Sometimes, it is quite deliberate and occurs at the
hands of those to whom Americans entrust their health.
Each year, American
dentists insert a metallic paste of mercury and silver into millions of
decayed teeth. And each year, American pediatricians inject millions of
infants and children with vaccines containing a mercury-based preservative
called Thimerosal. Both practices have generated controversy, with advocacy
groups claiming they cause a variety of disorders ranging from chronic
fatigue syndrome to multiple sclerosis, Alzheimer's disease, immune system
disorders and autism.
"Mercury exposure
from mercury dental fillings, also known as 'silver' fillings and
'amalgams,' is a lifelong threat," the Chronic Fatigue Syndrome
Network, or CFSN, asserts in a typical warning. "We believe mercury
from dental fillings to be an important toxin contributing to people with
CFIDS (chronic fatigue/immune disorder syndrome) and other immune system
disorders."
A cottage industry has
sprung up around such claims, often made by dentists advertising
amalgam-replacement procedures and companies peddling dietary supplements
intended to offset the alleged effects of dental mercury. The CFSN warning,
for example, is posted on a Web site where the organization offers to sell
nutritional supplements to restore levels of important enzymes depleted by
dental mercury exposure.
Numerous scientific
studies have looked for and failed to find any link between mercury
fillings and reduced brain function or illness (except in rare cases
involving an actual allergic reaction to mercury, found in less than 1
percent of the population). Researchers have found that people with amalgam
fillings do excrete higher amounts of mercury in their urine and feces than
people without such fillings, but that the levels in the body are too low
to produce any observable health effects.
The American Dental
Association contends that mercury amalgam fillings are safe and has warned
members that "it is against the ADA code of ethics for a dentist to
suggest or recommend the removal of amalgam restorations for the alleged
purpose of removing a toxic substance from the body." The U.S. Public
Health Service, the Food and Drug Administration, the World Health Organization,
the National Institutes of Health and the National Institute of Dental and
Craniofacial Research also have concluded mercury amalgam fillings are
safe.
Dental fillings do,
however, contribute measurably to the amount of mercury entering the
environment, where it can be transformed into a more dangerous form and
make its way into the food supply. Tiny quantities are often lost in the
sewer system during dental procedures, and the cumulative total can be
impressive.
According to Khalil
Abu-Saba, an environmental specialist with the San Francisco Bay Regional
Water Quality Control Board, mishandled dental amalgam accounts for most of
the 33 pounds of mercury estimated to flow into the bay each year in sewage
discharges from local treatment plants.
Once mercury enters the
water, it may be converted by microbes into its most dangerous form,
methylmercury, a neurotoxin that causes brain damage. Once it has been
converted to methylmercury, the contaminant can be absorbed by living
tissue.
Mercury in dental
fillings also makes its way directly into the air, through another avenue.
Abu-Saba estimates that 66 pounds of the toxic element is vaporized in the
Bay Area each year when crematories burn human bodies with fillings in
their teeth. That mercury eventually falls back to the soil or water and
contributes to fish contamination.
Although there is no
conclusive evidence linking dental fillings to illness or nervous system
damage, the case against Thimerosal in vaccines is more persuasive. The
Food and Drug Administration has determined that infants receiving multiple
injections of Thimerosal-containing vaccines may be exposed to mercury at
levels exceeding federal guidelines, potentially putting them at risk for
brain damage.
The American Academy of
Pediatrics, or AAP, and the U.S. Public Health Service have recommended
that the use of vaccines containing Thimerosal be reduced or eliminated and
that physicians choose vaccines without the preservative whenever the
option exists. According to the organizations' September 1999 report to
clinicians, vaccines for polio, measles, mumps, rubella, varicella,
rotavirus and Lyme disease do not contain Thimerosal. Nearly all the
diphtheria-tetanus-pertussis (DPT) vaccines do.
Many symptoms of autism
parallel those of mercury poisoning, which has led some parents of autistic
children to suggest a cause-effect relationship. The Autism Research
Institute, for example, points to the roughly simultaneous rise in the
reported incidence of autism and the increase in the number of routine
childhood vaccinations over the past 15 years as evidence of a link.
No peer-reviewed
medical study has confirmed such a relationship. The AAP stresses that
concern about possible adverse health effects from Thimerosal should not
prevent parents from having their children vaccinated.
"It is important
not to compromise the remarkable protection immunization now offers during
that particularly vulnerable time of life," the AAP says in its policy
statement on Thimerosal in vaccines.
(Contact John Krist of the
Ventura County Star in California at http://www.staronline.com.)
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