Dieci anni fa ho avuto modo di discutere l’articolo di Holmes AS e coll., di
cui copio l’abstract, col Professor Costantino
Salerno, biochimico dell’Università la Sapienza di Roma.
Il professore, commentando l’articolo, diceva: gli autori
danno del ridotto livello di mercurio nella prima ciocca di capelli dei neonati
la sola interpretazione che a loro piace: il mercurio è ridotto perché non
viene eliminato.
Questa è una delle interpretazioni possibili.
Dai dati in sé si potrebbe dedurre anche che il mercurio fa
bene, dal momento che nei bambini normodotati è più alto. La carenza di
eliminazione per un difetto degli enzimi a ciò deputati è un’ipotesi
interessante, ma va documentata.
Ben diverso è l’atteggiamento di Ilva Hertz Picciotto che,
avendo trovato livelli ematici e urinari di mercurio più bassi nei bambini con
autismo, ha fatto un’indagine alimentare che spiega il dato: i bambini con
autismo mangiano meno pesce in rapporto con
la nota selettività alimentare e, essendo il pesce la maggiore fonte di
mercurio, questo è sufficiente a spiegare il dato, contrario all’ipotesi di
partenza che era per un eccesso di mercurio nei bambini con autismo rispetto ai
controlli.
Mi sembra che i fautori della tossicità e i fautori del contrario abbiano atteggiamenti
più consoni agli stadi che alla scienza.
La stessa Hertz Picciotto, dopo avere presentato i suoi dati
negativi, dice che sarebbe utile spostare la ricerca a livello di gestanti o di
primo anno di vita, lasciando quindi
aperto il problema, che meriterebbe forse ulteriori ricerche da condurre in
scienza e coscienza, senza preconcetti né in un senso né nell’altro.
Reduced levels of mercury in first baby haircuts of autistic
children.
Source
SafeMinds, Cambridge, Massachusetts,
USA.
Abstract
Reported rates of autism have increased sharply in the United States and the United Kingdom. One possible factor
underlying these increases is increased exposure to mercury
through thimerosal-containing vaccines, but vaccine exposures need to be
evaluated in the context of cumulative exposures during gestation and early
infancy. Differential rates of postnatal mercury
elimination may explain why similar gestational and infant exposures produce
variable neurological effects. First baby haircut samples were obtained from 94
children diagnosed with autism using Diagnostic
and Statistical Manual of Mental Disorders, 4th edition (DSM IV) criteria and
45 age- and gender-matched controls. Information on diet, dental amalgam
fillings, vaccine history, Rho D immunoglobulin administration, and autism symptom severity was collected through a maternal
survey questionnaire and clinical observation. Hair
mercury levels in the autistic
group were 0.47 ppm versus 3.63 ppm in controls, a significant difference. The
mothers in the autistic group had significantly
higher levels of mercury exposure through Rho D
immunoglobulin injections and amalgam fillings than control mothers. Within the
autistic group, hair mercury levels varied significantly across mildly,
moderately, and severely autistic children, with
mean group levels of 0.79, 0.46, and 0.21 ppm, respectively. Hair mercury levels among
controls were significantly correlated with the number of the mothers' amalgam
fillings and their fish consumption as well as exposure to mercury through childhood vaccines, correlations that
were absent in the autistic group. Hair excretion patterns among autistic
infants were significantly reduced relative to control. These data cast doubt
on the efficacy of traditional hair analysis as a
measure of total mercury exposure in a subset of
the population. In light of the biological plausibility of mercury's role in neurodevelopmental disorders, the
present study provides further insight into one possible mechanism by which
early mercury exposures could increase the risk of
autism.
Blood mercury concentrations in CHARGE Study children with and
without autism.
Source
Department of Public Health
Sciences, University of California-Davis, Davis, California 95616-8638, USA.
ihp@ucdavis.edu
Abstract
BACKGROUND:
Some authors have reported
higher blood mercury (Hg) levels in persons with autism, relative to unaffected controls.
OBJECTIVES:
We compared blood total Hg
concentrations in children with autism or autism spectrum disorder
(AU/ASD) and typically developing (TD) controls in population-based samples,
and determined the role of fish consumption in differences observed.
METHODS:
The Childhood Autism Risk from Genetics and the Environment (CHARGE)
Study enrolled children 2-5 years of age. After diagnostic evaluation, we
analyzed three groups: AU/ASD, non-AU/ASD with developmental delay (DD), and population-based
TD controls. Mothers were interviewed about household, medical, and dietary
exposures. Blood Hg was measured by inductively coupled plasma mass
spectrometry. Multiple linear regression analysis was conducted (n = 452) to
predict blood Hg from diagnostic status controlling for Hg sources.
RESULTS:
Fish consumption strongly
predicted total Hg concentration. AU/ASD children ate less fish. After
adjustment for fish and other Hg sources, blood Hg levels in AU/ASD children
were similar to those of TD children (p = 0.75); this was also true among
non-fish eaters (p = 0.73). The direct effect of AU/ASD diagnosis on blood Hg
not through the indirect pathway of altered fish consumption was a 12%
reduction. DD children had lower blood Hg concentrations in all analyses.
Dental amalgams in children with gum-chewing or teeth-grinding habits predicted
higher levels.
CONCLUSIONS:
After accounting for
dietary and other differences in Hg exposures, total Hg in blood was neither
elevated nor reduced in CHARGE Study preschoolers with AU/ASD compared with
unaffected controls, and resembled those of nationally representative samples.