By Rosie Waterhouse (UK
Mercury in vaccines for babies and infants
could be the cause of a steep rise in cases of autism in children
around the world, according to a growing number of scientists.
The increase in reports of autism in Britain,
America and some other countries coincides with a growth in
the number of inoculations given to young children, say the
Many of the vaccines contain a preservative
which is 49.6% mercury
- a substance known to have neurotoxic effects, especially
in infants whose brains are still developing.
similar to those displayed by autistic children.
Autism is a spectrum of disorders that
range in severity from bizarre, violent behavior to an inability
to communicate or interact socially, along with repetitive
patterns of behavior.
Estimates of the prevalence of the syndrome
in Britain range from 10
cases per 10,000 of the population with "classic"
autism, to 9.1 cases per 1,000 showing some signs of autistic
The National Autistic Society estimates
that there are about 500,000 people with autism in Britain,
120,000 of them children. According to one recent study, there
has been a tenfold increase
among children between 1984 and 1994.
The new possible explanation of the rise
has emerged after a two-month review of all the available
information by The Sunday Times. Several groups of academics
and researchers in America and Sweden are investigating similar
theories that a combination of factors is to blame.
They include a genetic predisposition,
the cumulative effects of mercury in vaccines lowering the
immune system, with the controversial measles, mumps and rubella
(MMR) triple vaccine being a possible trigger.
The US Institute of Medicine is so concerned
that officials have organized a two-day meeting in July to
discuss the "hypothesis" that thiomersal and mercury
in vaccines are linked to autism.
Boyd Haley, chemistry professor at the
University of Kentucky, has been asked to submit a paper.
"Thiomersal is extremely toxic. The preliminary data
is convincing and does indicate that vaccines are the most
likely suspect for causing autism," he said.
In general, the researchers argue, the
cumulative effects of mercury impair
brain development and damage the child's immune system and
gastrointestinal tract, resulting in hypersensitivity
to toxic environmental substances.
This build-up could lead to autism or
a form of mercury poisoning - whose symptoms are similar.
In addition, researchers believe, the MMR triple vaccine,
usually given at 18 months to two years, could trigger autism
because the damaged immune system cannot cope with three live
viruses at once.
Only some children exposed to mercury
will develop symptoms. Researchers believe this indicates
that there may be a genetic predisposition. This theory was
reinforced by a study published this month that showed that
in 99% of autistic children a family of proteins essential
for disposing of mercury and other heavy metals is missing
The proteins, called metallothionein (MT),
are the main way in which the body counters heavy metal. The
study, by the Chicago-based Pfeiffer Center, a health research
institute, found that of 503 autistic patients 499 showed
an MT "dysfunction".
of vaccinations given to babies and children in Britain and
America has increased significantly.
In the United States the number given
before the age of two has risen from 8
in 1980 to 22 now.
In Britain in 1970, most children received
diphtheria, tetanus, polio, whooping cough and BCG for tuberculosis;
about half were also immunized against measles. In 1972 rubella
was added; MMR in 1988, Hib (Haemophilus Influenza type b),
against a form of meningitis in 1992, MMR as a second dose
in 1996, and meningitis C in 1999.
The MMR first dose is given between 12
and 15 months, with diphtheria and tetanus and the second
dose of MMR at three to five years.
MMR does not contain thiomersal, though
other child vaccines do. Thiomersal was introduced in the
1930s as a preservative and went into common use without review
by America's Food and Drug Administration (FDA) because it
was assumed to be safe.
In America, researchers found some infants
who are being vaccinated using multidose vials with thiomersal
can receive 62.5 micrograms of mercury per visit.
This is 100
times more than the intake considered safe for the average
six-month-old by the US Environmental Protection Agency.
In June 1999 the FDA discovered that:
"Infants who receive thiomersal-containing vaccine at
several visits may have been exposed to more mercury than
recommended by Federal guidelines." The following month
the European Agency for the Evaluation of Medicinal Products
(EMEA) issued a statement saying: "Cumulative exposure
to ethylmercury [found in thiomersal] . . . could lead to
a potential cause for concern."
In May last year, a scientist from the
US Centers for Disease Control and Prevention (CDC) gave a
presentation, based on a study of the Vaccine Safety Datalink
Project - a database of 400,000 children - with evidence of
harm. Dr Thomas Verstraeten of the CDC found the screening
analysis suggests "statistically significant associations"
between certain neurologic developmental disorders - such
as attention deficit disorder, and speech and language disorders
- and exposure to mercury from thiomersal-containing vaccines
before the age of six months.
As a result, the EMEA issued another statement
last June, saying: "For vaccination in infants and toddlers,
as a precautionary measure it would be prudent to promote
the general use of vaccines without thiomersal. Moreover,
the use of thiomersal-free
vaccines should be recommended for newborns."
Neither of these EMEA statements received
national newspaper publicity in Britain, and at least 10 thiomersal-containing
vaccines for children are still in use as drug manufacturers
are permitted to finish stocks.
Jane Maroney El-Dahr, an immunologist
at Tulane University medical center in New Orleans, said:
"It is important for me to emphasize that the message
is not to not vaccinate children, but to make sure that vaccines
The health department said: "Thiomersal
has played an important role as a preservative in vaccines.
Because thiomersal contains mercury, both
European and American regulators have recently recommended
that vaccine manufacturers phase out its use wherever possible
as a precaution. They have not recommended the withdrawal
of any vaccines.
Sunday Times - London