Thimerosal in childhood vaccines contributes to accumulating mercury toxicity in the kidney

Abstract

Mercury (Hg) is a hazardous chemical that accumulates in many cells and tissues, thereby producing toxicity. The kidney is a key target organ for Hg accumulation and toxicity. The contributing factors to Hg accumulation in humans include: (1) elemental and inorganic Hg exposure, often occurring by inhalation of Hg vapors; (2) exposure to methyl Hg (meHg), for example, through contaminated seafood; and (3) exposure to ethyl mercury (etHg) via thimerosal-containing vaccines. Systematic investigations on the toxic effects of etHg/thimerosal on the nervous system were carried out, and etHg/thimerosal emerged as a possible risk factor for autism and other neurodevelopmental disorders. There is, however, little known about the mechanisms and molecular interactions underlying toxicity of etHg/thimerosal in the kidney, which is the focus of the current review. Susceptible populations such as infants, pregnant women, and the elderly are exposed to etHg through thimerosal-containing vaccines, and in-depth study of the potential adverse effects on the kidney is needed. In general, toxicity occurring in association with different forms of Hg is related to: intracellular thiol metabolism and oxidative stress reactions; mitochondrial function; intracellular distribution and build-up of calcium; apoptosis; expression of stress proteins; and also interaction with the cytoskeleton. Available evidence for the etHginduced toxicity in the kidney was examined, and the main mechanisms and molecular interactions of cytotoxicity of etHg/thimerosal exposure in kidney described. Such accumulating knowledge may help to indicate molecular pathways that, if modulated, may better handle Hg-mediated toxicity.

Evidence on Neurotoxicity after Intrauterine and Childhood Exposure to Organomercurials

“…On the other hand, humans can also be exposed to organic Hg through the use of EtHg-containing vaccines [12]. Thimerosal-or sodium EtHg thiosalicylate-is made of 49.55% Hg by weight and has been added to multidose flask vaccines from 0.003% to 0.01% as a preservative [13][14][15]. Thimerosal was first synthesized in 1927 and has been used as a preservative in more than a few other pharmaceutical products such as cosmetics, eye drops, contact lens solutions, topical medicines as well as tattoo inks [15,16].…”

Avaliação da distribuição, metabolismo e nefrotoxicidade do timerosal - um conservante a base de mercúrio usado em vacinas - utilizando modelos in vivo e in vitro

“…Isto é consequência dos intensos debates sobre a possível associação da exposição humana ao timerosal na vacinas e o desenvolvimento de autismo e outras desordens neurocomportamentais (BALL, et al, 2001;SHARPE, et al, 2012). Em contrapartida, o rim -um órgão-alvo da toxicidade do Hg foi raramente estudado quanto aos mecanismos de toxicidade e morte celular considerando a exposição ao EtHg/timerosal (CARNEIRO, et al, 2013). …”

“…Até o momento, o único estudo que avaliou um potencial mecanismo de nefrotoxicidade do timerosal no tecido renal foi realizado por JAN e colaboradores que demonstraram que este agente organomercurial induz aumento de cálcio intracelular, em células renais caninas (Madin Darby canine kidney) (JAN, et al, 2003). No entanto, nenhum outro estudo foi realizado a fim de verificafr a toxicidade renal do timerosal/EtHg e seus mecanismos (CARNEIRO, et al, 2013 A análise descritiva foi usada para mostrar alguns resultados deste estudo. As concentrações de espécies de Hg (µg/ml ou µg/g) foram transformadas em µg -dividindo-se a concentração pela massa do respectivo órgão (g) ou volume de sangue (ml) -previamente determinados.…”

“…No entanto, existe pouca informação sobre os efeitos tóxicos nos rins após a administração de vacinas contendo timerosal. Até hoje, muito pouco se sabe sobre os mecanismos e interações moleculares subjacentes à toxicidade do EtHg/timerosal no rim (CARNEIRO, et al, 2013). Devido ao sistema imaturo/compromisso da função renal, recém-nascidos e pacientes renais, respectivamente, podem estar sob grande risco de toxicidade após exposição ao timerosal na vacinação e merece mais atenção e estudos.…”