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Vaccines
containing thiomersal | Full
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to the Editor
THE
World Health Organisation has launched an investigation into a possible
link between vaccines that contain mercury and a rise in the incidence of
autism among children in Britain.
The research will be
led by Dr Elizabeth Miller, head of the immunisation division of the
government's Public Health Laboratory Service.
She will analyse
records of 500 GP practices to check for a link between the use of vaccines
that contain the preservative thiomersal - which is almost 50% mercury -
and a range of neuro-developmental disorders including autism.
There has been a big
rise in the number of children exhibiting mild to severe neurological
problems such as dyslexia and autism. This follows the introduction of the
measles, mumps and rubella (MMR) vaccine in 1988 and a sharp rise in the
number of mercury-based vaccines given.
The number of
vaccinations that can be given before the age of two has risen from about
eight in 1980 to 22 now.
A key factor may be
that mercury-based vaccines are being given to babies as young as two
months old, when their bodies are less able to cope with it.
Research by the
Scottish-based Action Against Autism group shows that the number of
children in English schools who have received "statements" for
special educational needs rose from 140,000 in 1990 to more than 250,000 in
2000. In Scotland the number of children with a similar "record of
needs" rose from just over 8,000 to more than 15,000.
Vaccines containing
mercury include the triple DTP injection against diphtheria, tetanus and
whooping cough and some licensed brands of Hib, a meningitis vaccine.
Mercury is not used in the MMR vaccine.
Dr John Clements, of
the WHO's immunisation programme, said last week: "We have permitted
the use of thiomersal in vaccines for many years as an essential
preservative in multi-dose vials. The study is to see if there is any
evidence of a negative effect."
In America, where there
has been a similar steep rise in autism, a survey by the Centers for
Disease Control and Prevention has found a "statistically
significant" link between mercury in vaccines and developmental
disorders, including Attention Deficit Disorder and speech and language
delays.
An accumulation of
mercury may damage the brain, central nervous system and gastro-intestinal
tract and lower the child's immune system so it cannot cope with the MMR
vaccine, which may trigger autism.
In 1999 the US Food and
Drug Administration (FDA) revealed that the amount of mercury intake in
vaccination in babies in their first six months exceeded the limit set by
the Environmental Protection Agency. As a result the FDA and the European
Agency for the Evaluation of Medicinal Products said thiomersal would be
phased out of vaccines, but manufacturers have been permitted to use up
their stocks.
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