On Tue, 17 Feb 2004 05:21:55 GMT, "Andrew" <
[email protected]>
wrote:
>
>"Jeff"
[email protected] wrote:
>>
>> And with the bottom line being tht there is no scientific reason to beleive that thimersal causes
>> autism, Geier's view has nothing to do with science.
>
>Except that the signs of ethyl mercury (thimerosal) poisoning are exactly the SAME as the signs
>of autism!
Wrong. This is more ******** spouted by the uneducated, antivaccine armchair autism theorists,
along the lines of other such claims such as "MMR contains thimerosal," and "autism experts
recommend separating the components of MMR." Repeating nonsense over and over again doesn't make it
become true.
Read this:
http://pediatrics.aappublications.org/cgi/reprint/111/3/674.pdf
Karin B. Nelson and Margaret L. Bauman. Thimerosal and Autism? Pediatrics, Mar 2003; 111:674 - 679.
An excerpt follows.
=============
ARE THE CLINICAL MANIFESTATIONS OF AUTISM SIMILAR TO THOSE OF RECOGNIZED MERCURY TOXICITY?
Bernard et al(1) present a table listing ~95 clinical findings they consider to be shared by autism
and mercury poisoning. Their table does not distinguish typical and characteristic manifestations of
either disorder from the rare, unusual, and highly atypical.
In mercury poisoning, the characteristic motor findings are ataxia and dysarthria (Table 1).(5,6)
These signs, along with tremor, muscle pains, and weakness, are noted on relatively high-dose
exposure, acute or chronic. In 3 Romanian children accidentally exposed to ethyl mercury in a
fungicide, these same symptoms were prominent.(7) The outcome of fetal methyl mercury poisoning in
severe form also included spasticity.(8) In contrast, in autism, the only common motor
manifestations are repetitive behaviors (stereotypies) such as flapping, circling, or rocking.
Persons with Asperger syndrome may be clumsy, and hypotonia has been noted in some infants with
autism; the frequency of clumsiness and hypotonia in autism spectrum disorders is not established.
No other motor findings are common in autism, and indeed the presence of ataxia or dysarthria in a
child whose behavior has autistic features should lead to careful medical evaluation for an
alternative or additional diagnosis.
The most characteristic sensory finding of mercury poisoning is a highly specific bilateral
constriction of visual fields.(5,6,9) With lesser exposure there may be compromise of contrast
sensitivity.(10,11) In addition, there may be paresthesias or, in infants, erythema and pain in
hands and feet because of peripheral neuropathy. In autism, decreased responsiveness to pain is
sometimes observed along with hypersensitivity to other sensory stimuli, including hyperacusis. The
"sensory defensiveness" of autism seems to reflect altered sensory processing within the brain
rather than peripheral nerve involvement.(12–14)
Other signs that may appear in children with chronic mercury toxicity, such as hypertension,(15)
skin eruption,(16) and thrombocytopenia,(17) are seldom seen in autism.
In relatively mild mercurism in persons without characteristic motor or sensory changes, psychiatric
symptomatology may be absent, and if present is nonspecific, with findings such as depression,
anxiety, and irritability.(18–20) There may be impairment of recent memory. Even for individuals
with known elevated postmortem levels of mercury in brain, it may be impossible to conclude whether
the nonspecific psychiatric findings they demonstrated in life were the result of mercury
toxicity.(21)
When severe mercury poisoning occurs in prenatal life or early infancy, head size tends to be small
and microcephaly is common.(22) Prenatal exposure to other neurotoxins—lead, alcohol, and
polychlorinated biphenyls, for example—also predispose to decreased head size. In contrast, in
autism increasing evidence indicates that head size(23–25) and, as measured by volumetric magnetic
resonance imaging, brain size(26,27) tends to be larger than population norms.
At sufficient dose mercury is indeed a neurotoxin, but the typical clinical signs of mercurism are
not similar to the typical clinical signs of autism.