PARIS -- Mercury has been fingered in a study as a
possible cause of autism, the British weekly New
Scientist reports in its June 21, 2003 issue.
A US team compared mercury levels in hair that had
been kept from 139 babies when they had their first
haircuts, when they were around 18 months old.
Mercury levels among 94 children who were later
diagnosed as autistic was 0.47 parts per million (ppm),
while among the 45 other children who developed
normally, the levels were eight times higher, at 3.63
ppm.
The lower the level of mercury, the worse the degree
of autism, the scientists found.
The results are remarkable but until more work is
carried out, the conclusions are open to dispute, New
Scientist says.
The clear implication is that autistic children have
a genetic flaw that makes them vulnerable in their
exposure to essential or toxic metals.
It could be that these children cannot get rid of
mercury via their faeces and urine, which means that the
toxic metal may accumulate in their brain cells and
affect their neurological development.
Alternatively, mercury may not be to blame. The
difference in mercury levels in the hair could be an
indicator of a general problem these children may have
in dealing with metals.
Autistic children, according to this line of
thinking, may be deficient in processing zinc, iron and
copper and other metals essential for brain development.
The research, led by Louisiana doctor Amy Holmes,
will be published in September in the International
Journal of Toxicology, New Scientist said.
Parents of autistic children have filed lawsuits in
North America, blaming vaccines containing a
mercury-based preservative called thimerosal for their
child's plight.
Other parents, notably in Britain, blame a triple
vaccine for measles, mumps and rubella for causing their
child's autism. However, this vaccine does not contain
any mercury at all, and most scientists say that in any
case the evidence against the vaccine is not convincing.
Dr Holmes' study said the children's only significant
source of mercury came from their mothers while they
were in the womb.
A check on the family's background, health and eating
habits found the biggest sources were the mother's
mercury amalgam fillings; immunoglobulin injections
containing thimerosal for women whose blood-group was
Rhesus negative; and heavy consumption of fish, defined
as more than five fish meals a month. -- AFP
