Science Library Category:

Environmental Factors

Published: 2016
SYNOPSIS

Children with ASD have higher urinary levels of mercury and lead.

TITLE

Altered urinary porphyrins and mercury exposure as biomarkers for autism severity in Egyptian children with autism spectrum disorder

CITATION

Eman M. Khaled, Nagwa A. Meguid, Geir Bjørklund, Amr Gouda, Mohamed H. Bahary, Adel Hashish, Nermin M. Sallam, Salvatore Chirumbolo, Mona A. El-Bana. Metabolic Brain Disease, (2016), DOI 10.1007/s11011-016-9870-6.

SUMMARY

Results of this case-control study showed that children with ASD had higher urinary levels of mercury and lead as well as porphyrins that are characteristic of mercury toxicity as compared to non-ASD control children. Porphyrins are complex molecules that are processed in the body through a series of chemical reactions. Mercury poisons the enzymes that are needed in the process, causing a buildup in the body of excess levels of specific porphyrins. The porphyrins for mercury toxicity also correlated with autism severity in ASD patients.

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Published: 2016
SYNOPSIS

Thimerosal reduces people’s ability to make all-important vitamin B12 compounds that help the body detoxify and control inflammation—and B12 deficiencies and severely impaired detoxification are hallmarks of autism.

TITLE

Alternatively Spliced Methionine Synthase in SH-SY5Y Neuroblastoma Cells: Cobalamin and GSH Dependence and Inhibitory Effects of Neurotoxic Metals and Thimerosal

CITATION

Mostafa Waly, et al. Oxidative Medicine and Cellular Longevity, Volume 2016, Article ID 6143753, 11 pages.

SUMMARY

Thimerosal inhibited cellular production of cobalamin necessary for detoxification and amelioration of oxidative stress. This caused lower methionine synthase activity and an impaired methylation capacity. Autistic subjects in general show cobalamin deficiencies and several impaired methylation.

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Published: 2015
SYNOPSIS

Levels of mercury, lead, and aluminum in the hair of autistic children are higher than controls. Environmental exposure to these toxic heavy metals, at key times in development, may play a causal role in autism.

TITLE

Assessment of Hair Aluminum, Lead, and Mercury in a Sample of Autistic Egyptian Children: Environmental Risk Factors of Heavy Metals in Autism

CITATION

Farida El Baz Mohamed, Eman Ahmed Zaky, Adel Bassuoni El-Sayed, Reham Mohammed Elhossieny, Sally Soliman Zahra, Waleed Salah Eldin, Walaa Yousef Youssef, Rania Abdelmgeed Khaled, and Azza Mohamed Youssef. Behavioural Neurology, Volume 2015, Article ID 545674, 9 pages September 2015.

SUMMARY

The etiological factors involved in the etiology of autism remain elusive and controversial, but both genetic and environmental factors have been implicated. The aim of this study was to assess the levels and possible environmental risk factors and sources of exposure to mercury, lead, and aluminum in children with autism spectrum disorder (ASD) as compared to their
matched controls. Researchers found, autistic case children show significantly higher levels of hair mercury as compared to non-autistic control children. In general, autistic children accumulated metals at a much higher level that control children who did not have a diagnosis of autism.

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Published: 2015
SYNOPSIS

Thimerosal exposure led to the death of neuroblastoma and liver cells due to inhibition of thioredoxin-based cellular metabolism. This is similar to neuronal damage associated with autistic disorder.

TITLE

Toxicological effects of thiomersal and ethylmercury: Inhibition of the thioredoxin system and NADP+-dependent dehydrogenases of the pentose phosphate pathway

CITATION

Juan Rodrigues, Vasco Branc, Jun Lu, Arne Holmgren, Cristina Carvalho. Toxicology and Applied Pharmacology, 286 (2015) 216–223.

SUMMARY

This study demonstrates that Thimerosal and especially Ethylmercury affect specifically the antioxidant thioredoxin cycle and the production of NADPH by impairing the oxidative branch of the pentose phosphate pathway, therefore showing that Trx, TrxR, G6PDH and 6PGDH are important molecular targets for these mercurial compounds. The impairment of these enzymes originates detrimental effects which are especially relevant to the central nervous system.

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Published: 2005
SYNOPSIS

Many heavy metals increase the apparent toxicity of low levels of mercury.

TITLE

Mercury toxicity: Genetic susceptibility and synergistic effects

CITATION

B.E. Haley. Medical Veritas, 2 (2005) 535–542.

SUMMARY

This article discusses mercury intoxication and several normally appearing factors that increase the susceptibility to mercury toxicity. Boys with autism represent a subset of the population that is more susceptible to the toxic effects of mercury and thimerosal because they are not efficient excretors of these toxic materials. Research confirms that a lead toxic person would be more susceptible to mercury toxicity than a healthy, non-toxic person researchers routinely observed that many heavy metals increase the apparent toxicity of low levels of mercury. In other words, the synergistic effects of other heavy metals, diet, antibiotics, etc. on mercury toxicity make it impossible to define a “safe level of mercury exposure.”

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