Chemical Elements in Hair and Their Association with Autism Spectrum Disorder: A Comprehensive Systematic Review

Abstract

Background: Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition with increasing prevalence. This review aims to systematically investigate the relationship between the levels of toxic and trace elements in hair and the occurrence of ASD. Methods: Original articles reporting trace element levels in hair were included. A comprehensive search was conducted in databases such as Medline (via PubMed), Scopus, Web of Science, and Google Scholar, covering publications from 1 January 2000, to 2 January 2023. Keywords including “hair element analysis”, “trace elements”, and “autism”, were utilized in the search. Results: A direct comparison of the data was not possible due to the variety of methodologies observed in the available studies, including variations in sample sizes and analytical procedures. Conclusions: Exposure to toxic elements, notably Mercury (Hg) and Lead (Pb), which act as neurotoxicants, was found to be associated with the pathogenesis of ASD. Furthermore, a significant correlation was identified between the Zinc (Zn) to Copper (Cu) ratio and ASD.

Environmental Impact of the Heavy Metal Intoxication on Metabolic, Physiological and Nutritional Profiles in Children with Autism Spectrum Disorder in Morocco

“…Toxic metals and metalloids such as arsenic (As), lead (Pb), chromium (Cr), and cadmium (Cd), generally considered as potential environmental risk factors in ASD, were quantified in the hair of children with ASD. This approach uses hair as a biological matrix representative of the body's metal impregnation, offering the advantage of being non-invasive, painless, and particularly practical for a non-cooperative population such as children with ASD (Chojnacka and Mikulewicz, 2023) Previous studies examining the link between toxic metals found in hair and children with ASD yielded similar outcomes. For instance, Elsheshtawy et al (2011) discovered substantial differences in the levels of these substances in the hair of children with autism compared to controls.…”