Hair Toxic Metal Concentrations and Autism Spectrum Disorder Severity in Young Children

Institute of Chronic Illnesses, 14 Redgate Ct, Silver Spring, MD 20905, USA. .
International Journal of Environmental Research and Public Health (Impact Factor: 2.06). 12/2012; 9(12):4486-4497. DOI: 10.3390/ijerph9124486
Source: PubMed


Previous studies have found a higher body-burden of toxic metals, particularly mercury (Hg), among subjects diagnosed with an autism spectrum disorder (ASD) in comparison to neurotypical controls. Moreover, Hg body-burden was associated with ASD severity. This cross-sectional study examined the potential correlation between hair toxic metal concentrations and ASD severity in a prospective cohort of participants diagnosed with moderate to severe ASD. The Institutional Review Board at the University of Texas Southwestern Medical Center at Dallas (Dallas, TX) approved the present study. Qualifying study participants (n = 18) were evaluated for ASD severity using the Childhood Autism Rating Scale (CARS) and quantitatively for arsenic, Hg, cadmium, lead, chromium, cobalt, nickel, aluminum, tin, uranium, and manganese using hair toxic element testing by Doctor's Data (a CLIA-approved laboratory). CARS scoring and hair toxic element testing were blinded to one another. Increasing hair Hg concentrations significantly correlated with increased ASD severity. In contrast, no significant correlations were observed between any other of the hair toxic metals examined and ASD severity. This study helps to provide additional mechanistic support for Hg in the etiology of ASD severity, and is supported by an increasing number of recent critical reviews that provide biological plausibility for the role of Hg exposure in the pathogenesis of ASDs.

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    • "Among the hazardous toxicants, heavy metals, known neurotoxicants continue to be of a great concern due to their increasing anthropogenic presence in the environment [26]. Several epidemiological studies reported a relationship between autism and heavy metal biomarkers [27] [28]. Exposure to industrial chemicals has been thought to play a role in the etiology of autism through epigenetic mechanisms. "
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    ABSTRACT: We tested the hypothesis that in utero exposure to heavy metals increases autism-like behavioral phenotypes in adult animals and induces epigenetic changes in genes that have roles in the etiology of autism. Mouse dams were treated with cadmium, lead, arsenate, manganese, and mercury via drinking water from gestational days (E) 1–10. Valproic acid (VPA) injected intraperitoneally once on (E) 8.5 served as a positive control. Young male offspring were tested for behavioral deficits using four standardized behavioral assays. In this study, in utero exposure to heavy metals resulted in multiple behavioral abnormalities that persisted into adulthood. VPA and manganese induced changes in perseverative/impulsive behavior and social dominance behavior, arsenic caused changes only in perseverative/impulsive behavior, and lead induced abnormalities in social interaction in comparison to the control animals. Brain samples from Mn, Pb, and VPA treated and control animals were evaluated for changes in CpG island methylation in promoter regions and associated changes in gene expression. The Chd7 gene, essential for neural crest cell migration and patterning, was found to be hypomethylated in each experimental animal tested compared to water-treated controls. Furthermore, distinct patterns of CpG island methylation yielded novel candidate genes for further investigation.
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    • "Mercury (Hg) concentration ranged from 0.12 to 85.9 mg@BULLETL −1 with an average of 18.94 mg@BULLETL −1 (Table 1, Figure 1). Pb and Hg are linked with neurodevelopment problems and possible autistic disorders in children [10] [11]. Six percent of the samples contained Hg concentration above the allowable value (Table 1). "
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    ABSTRACT: The main aim of this study is to assess the quality of inexpensive plastic toys imported to Pales-tinian Markets. The content of heavy metals (Pb, Cd, Cr, Hg, As, Se, Ba, and Zn) was analyzed in 50 plastic toys purchased from local markets in Palestine and 17 plastic toys purchased from Israeli markets for comparison. After the digestion of samples with concentrated nitric acids and hydro-gen peroxide using a microwave digester, the concentrations of the selected heavy metals were determined by ICP-MS Agilent 7500 in Al-Quds University. Results revealed that 40% of the Pales-tinian toy samples had high concentration (above international limits) of Pb, 30% of Cd, 34% of Cr, 6% of Hg, 42% of As, 32% of Se, 20% of Ba, and 40% of Zn. On the other hand, 95% of the Israeli samples were safe, and their concentrations were less than the maximum internationally allowa-ble limits. In the same context, ten toy samples (2.5 gm each) had been crushed and dipped for 8 hours in a solution of artificial saliva. The solution was acidified and tested for heavy metal con-centrations, but none of the migration concentrations exceeded the international maximum al-lowable limit. High levels of heavy metal concentrations, found in the plastic toys from the Pales-tinian markets could form a health hazard to children and put their lives at risk. It could be also an indirect source for environmental pollution.
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    • "These studies indicate that children with autism have a decreased ability to excrete toxic metals, leading to a higher body burden. Moreover, studies show that Hg body-burden is associated with increased ASD severity (Lakshmi Priya and Geetha 2011, Elsheshtawy et al. 2011, Geier et al. 2012, Adams et al. 2013). "
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    ABSTRACT: Autism spectrum disorders (ASDs) are a group of developmental disabilities that can cause significant social, communication and behavioral challenges. Several studies have suggested a disturbance in the copper (Cu) and zinc (Zn) metabolism in ASDs. Zinc deficiency, excess Cu levels, and low Zn/Cu ratio are common in children diagnosed with an ASD. The literature also suggests that mercury accumulation may occur as a cause or consequence of metallothionein (MT) dysfunction in children diagnosed with an ASD, which may be one of the causes of Zn deficiency. MTs are proteins with important functions in metal metabolism and protection. Zinc and Cu bind to and participate in the control of the synthesis of MT proteins. Studies indicate that the GABAergic system may be involved in ASDs, and that Zn and Cu may play a role in this system.
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