Developmental Neurotoxicity of Traffic-Related Air Pollution: Focus on Autism

Abstract

Purpose of Review Epidemiological and animal studies suggest that air pollution may negatively affect the central nervous system (CNS) and contribute to CNS diseases. Traffic-related air pollution is a major contributor to global air pollution, and diesel exhaust (DE) is its most important component. Recent findings Several studies suggest that young individuals may be particularly susceptible to air pollution-induced neurotoxicity, and that perinatal exposure may cause or contribute to developmental disabilities and behavioral abnormalities. In particular, a number of recent studies have found associations between exposures to traffic-related air pollution and autism spectrum disorders (ASD), which are characterized by impairment in socialization and in communication, and by the presence of repetitive and unusual behaviors. The cause(s) of ASD are unknown, and while it may have a hereditary component, environmental factors are increasingly suspected as playing a pivotal role in its etiology, particularly in genetically susceptible individuals. Summary Autistic children present higher levels of neuroinflammation and systemic inflammation, which are also hallmarks of exposure to traffic-related air pollution. Gene-environment interactions may play a relevant role in determining individual susceptibility to air pollution developmental neurotoxicity. Given the worldwide presence of elevated air pollution, studies on its effects and mechanisms on the developing brain, genetic susceptibility, role in neurodevelopmental disorders, and possible therapeutic interventions, are certainly warranted.

Ambient concentrations of NO2 and hospital admissions for schizophrenia

“…Exposure to NO 2 may increase the risk of schizophrenia admissions through increased neuroinflammation and oxidative stress,28 29 as supported by the following findings from animal studies: associations between diesel exhaust inhalation and neuroinflammation in brain regions,30 relationship between NO 2 inhalation and brain pathology, lower antioxidant defences and deregulation of apoptosis-related genes expression,31 links between diesel exhaust and microglial activation and upregulation of oxidative stress,28 and associations between vehicle emissions and anxiety-like behaviour, depression-like behaviour, neurobehavioural as well as cognitive deficits 24. Epidemiological research also indicated that traffic-related air pollution was associated with autism and decreased cognitive function 11 32 33.…”

Effects of PM2.5 and gases exposure during prenatal and early-life on autism–like phenotypes in male rat offspring

“…Although genetics likely plays an important role in ASD, environmental exposures to pollutants particularly during the early life periods could be another potential risk factor [6,7]. Environmental factors such as exposure to air pollution may contribute to ASD etiology [8][9][10].…”

Particulate Matter Exposure and Attention-Deficit/Hyperactivity Disorder in Children: A Systematic Review of Epidemiological Studies

“…Evidence accumulated from human epidemiological and animal studies indicates that ambient air pollution may be associated with diseases of the central nervous system (CNS) [34]. Children are particularly susceptible to air pollutants, and pre-and/or postnatal exposure may negatively affect their CNS [35]. Recently, several investigation studies have integrated magnetic resonance imaging of the brain with epidemiology, showing that long-term exposure to air pollution might have adverse impacts on the human brain [36].…”