Exposure to Inorganic Arsenic and Lead and Autism Spectrum Disorder in Children: A Systematic Review and Meta-Analysis

Abstract

Inorganic arsenic (iAs) and lead (Pb) rank first and second on the U.S. Environmental Protection Agency’s priority list of hazardous substances. Both are known neurotoxic metals that cause detrimental effects on brain development and lead to deficits in cognitive function and behavioral performance in children. Studies have indicated a potential link between iAs and Pb exposure and a higher risk for autism spectrum disorder (ASD). To provide further insight into whether developmental exposure to iAs or Pb is associated with ASD, we conducted a systematic review and combined data into a meta-analysis to evaluate the available human evidence on the relationships. We systematically reviewed relevant studies published through December 30, 2018 and identified 14 studies on iAs and 37 studies on Pb exposure and their respective associations with ASD. Among them, 8 (53.3%) and 19 (51.3%) studies reported a positive association for iAs and Pb, respectively, and none reported a sole inverse association. In the following meta-analysis, we found statistically significant higher iAs concentrations, in hair and in blood, for children diagnosed with ASD compared with controls across studies. However, the findings on Pb exposure were inconsistent, with a significant association for hair Pb, no association for urinary Pb, and an inverse association for blood Pb. After considering strengths and limitations of the body of research, we concluded that there is consistent evidence supporting a positive association between early life iAs exposure and diagnosis of ASD and inconsistent evidence for Pb exposure and ASD risk. We believe it is in the best interest of policy makers and the public to reduce exposures to iAs and Pb among pregnant women and children. Further, our research supports the need for large perspective human studies with accurate measurement and determination of the long-term body burden of iAs and Pb exposures to assess the impact of iAs and Pb exposures on ASD risk.

Mechanisms of Metal-Induced Mitochondrial Dysfunction in Neurological Disorders

“…In addition, Mn and Pb were also associated with the severity and characteristics of ASD [ 129 ]. A systematic review and meta-analysis concluded that early life iAS exposure is positively associated with ASD, and the relationship between lead exposure and autism risk is controversial [ 130 ]. Another recent systematic review and meta-analysis indicated that existing evidence supports significant associations between ASD and Al, Cd, and Hg, respectively [ 131 ].…”

Analysis of lead, arsenic and calcium content in the hair of children with autism spectrum disorder

“…There is a list of 201 industrial chemical agents that have a neurotoxic effect on humans (including Pb and As). They may cause autism and other disorders such as attention deficit, mental retardation, and cerebral palsy [1,16,17,23,24].…”

“…In children whose mothers were exposed to As compounds, the following symptoms are observed: difficulty with learning, memory, concentration, cognitive and behavioral disorders. Children exposed to this element may also present the symptoms of retarded development or inhibited physical and mental development [1,5,6,13,23,[29][30][31][32][33][34][35].…”

“…However, investigations on associations between ASD and neurotoxic heavy metals are inconclusive. Over the last decades, numerous studies have reported a relationship between ASD and Pb and As exposure [5,[11][12][13][16][17][18][19][20][21][22][23][24]. However, there are also some reports that conclude that heavy metals exposure is not a risk factor for ASD [6,14,[25][26][27][28][29].…”

The Role of Electrospun Nanomaterials in the Future of Energy and Environment

“…For instance, inorganic arsenic, cadmium, lead, and mercury are among the ten chemicals/groups of chemicals of major public health concern according to World Health Organization (WHO) [148]. Studies have shown that these metal/metalloids associated with numerous diseases such as development of autism spectrum disorder in children [149], skin pigmentation change and lesions [150], liver and renal diseases [151], neural diseases and anemia [152].…”