The contribution of environmental pollutants to the risk of autism and other neurodevelopmental disorders: A systematic review of case-control studies.

Exposure to environmental pollutants, such as metals, pesticides, and air pollutants during early life, is a risk factor for neurodevelopmental disorders (NDDs), including Autism Spectrum Disorder (ASD). Our systematic review aimed to select and summarize more recent case-control studies that examined the association between prenatal and early postnatal exposure to environmental pollutants and NDDs. We searched five databases (Web of Science, PubMed, Embase, Scopus, Ovid), screened 2261 records, and included 24 eligible case-control studies. Meta-analyses were conducted on subgroups of at least three studies that shared both the outcome and the exposure. A noteworthy discovery from this literature review is the existence of non-linear or non-monotonic dose-response relationships between the exposure to certain metals and the risk of ASD. The meta-analysis revealed a significant association between exposure to particular matter (PM) during the first year of life and the risk of ASD. Overall, studies included in our systematic review indicate that exposure to several pollutants within the first three years of life was significantly associated with the risk of NDDs.