Neurotoxic character of thimerosal and the allometric extrapolation of adult clearance half‐time to infants

Magós, L.

doi:10.1002/jat.918

Cited by 62 publications

(52 citation statements)

References 17 publications

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“…This conclusion is the same as that reported by others in studies of infant monkeys (Burbacher et al, 2005), mice (Harry et al, 2004) and in rats (Magos et al, 1985;Magos, 2003). The many fold higher brain levels of organic mercury for methyl compared with the same dose of ethyl mercury is especially noteworthy.…”

Section: Discussionsupporting

confidence: 84%

Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury

Zaręba

Cernichiari

Hojo

et al. 2007

J of Applied Toxicology

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Thimerosal, which releases the ethyl mercury radical as the active species, has been used as a preservative in many currently marketed vaccines throughout the world. Because of concerns that its toxicity could be similar to that of methyl mercury, it is no longer incorporated in many vaccines in the United States. There are reasons to believe, however, that the disposition and toxicity of ethyl mercury compounds, including thimerosal, may differ substantially from those of the methyl form. The current study sought to compare, in neonatal mice, the tissue concentrations, disposition and metabolism of thimerosal with that of methyl mercury. ICR mice were given single intramuscular injections of thimerosal or methyl mercury (1.4 mg Hg kg(-1)) on postnatal day 10 (PND 10). Tissue samples were collected daily on PND 11-14. Most analysed tissues demonstrated different patterns of tissue distribution and a different rate of mercury decomposition. The mean organic mercury in the brain and kidneys was significantly lower in mice treated with thimerosal than in the methyl mercury-treated group. In the brain, thimerosal-exposed mice showed a steady decrease of organic mercury levels following the initial peak, whereas in the methyl mercury-exposed mice, concentrations peaked on day 2 after exposure. In the kidneys, thimerosal-exposed mice retained significantly higher inorganic mercury levels than methyl mercury-treated mice. In the liver both organic and inorganic mercury concentrations were significantly higher in thimerosal-exposed mice than in the methyl mercury group. Ethyl mercury was incorporated into growing hair in a similar manner to methyl mercury. The data showing significant kinetic differences in tissue distribution and metabolism of mercury species challenge the assumption that ethyl mercury is toxicologically identical to methyl mercury.

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Section: Discussionsupporting

confidence: 84%

Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury

Zaręba

Cernichiari

Hojo

et al. 2007

J of Applied Toxicology

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“…Desde hace varios años, estudios in vivo hechos en roedores habían mostrado que el etilmercurio era capaz de atravesar las membranas celulares y luego ser convertido intracelularmente a Hg inorgánico, el mismo que se acumula preferentemente en el cerebro y los riñones. Dicha acumulación intracelular de Hg inorgánico demostró ser mayor para el etilmercurio (timerosal), en relación al metilmercurio empleando exposiciones equimolares, pese a que la velocidad de depuración sanguínea del etilmercurio es definitivamente más rápida que la del metilmercurio ( 152 ). No obstante, se ha determinado que no existen mayores diferencias entre la toxicidad del metilmercurio y el timerosal.…”

Section: Estudios En Modelos Animalesunclassified

El timerosal y las enfermedades del neurodesarrollo infantil

Maya

Luna

2013

An Fac med

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Resumen Se evalúa la relación causal entre el timerosal (etilmercurio), como preservante en las vacunas pediátricas, y el incremento de casos de enfermedades del neurodesarrollo infantil, como consecuencia de la ampliación de los esquemas de inmunización. Se revisó la información científica, relacionando el timerosal y las evidencias que permitan evaluar una posible asociación causal, con estudios epidemiológicos, ecológicos, biomoleculares y toxicológicos, de bioseguridad, toxicológicos fetales y sobre salud reproductiva. Se encontró múltiples asociaciones entre la exposición a timerosal y las enfermedades del neurodesarrollo infantil. Tal neurotoxicidad ocurre en los infantes y fetos de gestantes vacunadas por dosis acumulativa de mercurio. Las diversas evidencias implican al timerosal como el agente causante, agravante o disparador de las enfermedades del neurodesarrollo infantil. La toxicidad del mercurio obligó al retiro progresivo del timerosal de los medicamentos. Lamentablemente, en las vacunas, ha habido una sustancial demora en la demostración de su impacto negativo. Actualmente, existen vacunas sin timerosal, cuyo uso está ocasionando la disminución de la incidencia de las enfermedades del neurodesarrollo infantil. Palabras claveTimerosal; autismo; enfermedades del sistema nervioso; desarrollo infantil; vacunas. Thimerosal and children's neurodevelopmental disorders AbstractThe causal relation of thimerosal (ethylmercury) Dichas estadísticas convertían a los DEA en la mayor epidemia de enfermedades mentales jamás observada en la historia de los EE.UU., significando más casos que enfermedades, tales como el síndrome de Down, la diabetes mellitus tipo 1 y el cáncer pediátrico ( 8 ). Si bien en nuestro medio aún no disponemos de datos estadísticos que estimen la magnitud de este problema, varios países en todo el mundo simultáneamente han notificado incrementos similares. En la China, por ejemplo, donde los DEA eran prácticamente desconocidos, coincidiendo con la introducción de las compañías norteamericanas productoras de vacunas a partir del año 1999, se ha informado sobre 1,8 millones de niños autistas recientemente diagnosticados; asimismo, los DEA también se han incrementado significativamente en la India, Nicaragua, Argentina y en otros países en vías de desarrollo, durante los últimos años ( 19 ). El hecho de observar tan impresionante aumento de casos, como el descrito, descartaba definitivamente la hipó-tesis de que estas enfermedades fueran debidas exclusivamente a un trastorno genético, pues dichas condiciones tardan muchos años en desarrollarse y nunca alcanzan cifras epidémicas, salvo exposiciones ionizantes o catástrofes nucleares.Algunos investigadores adujeron que tal fenómeno podría deberse a cambios y mejoras en los criterios de diagnóstico. Sin embargo, a pesar que desde el año 1994 se comenzó a aplicar en los EE.UU. y en todo el mundo los criterios del DSM IV (Diagnostic and Statistical Manual 4 th Ed.), como fuente obligatoria para el diagnóstico de las enfermedades mentales, ...

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“…However, some studies have not shown significant adverse effects from methylmercury exposure (Marsh, Turner, Smith, Allen, & Richdale, 1995;McKeown-Eyssen, Ruedy, & Neims, 1983;Myers et al, 2003). One animal study has shown differential neurotoxic effects between ethylmercury and methylmercury (Magos, 2003), suggesting ethylmercury may be less toxic due to increased protective potency of the blood brain barrier as well as a shorter half life. In addition to the results of MMR vaccine epidemiological studies, although thimerosal has been largely removed from vaccines in the United States since 1999, increases in autism prevalence has remain unchanged.…”

Section: Alternative Theoriesmentioning

confidence: 99%

A Review on the Cognitive Neuroscience of Autism

Koyama

2009

Act Nerv Super

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With increased recognition in the media, heightened prevalence, and advances in research technologies, investigation into the causes of autism has broadened in recent years. Studies at the molecular, structural, and behavioral levels have resulted in significant findings, linking autism to qualitative differences in neurological function and an alteration of early development. Familial aggregation of autism demonstrates a strong genetic factor, although genetics can not completely account for its pathogenesis. Studies show autism having one of the most complex pathologies among neurodevelopmental disorders. Future studies applying sophisticated methodologies in new areas may shed light on current mysteries surrounding the disorder.

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Neurotoxic character of thimerosal and the allometric extrapolation of adult clearance half‐time to infants

Cited by 62 publications

References 17 publications

Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury

Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury

El timerosal y las enfermedades del neurodesarrollo infantil

A Review on the Cognitive Neuroscience of Autism

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