Systematic review of prenatal exposure to endocrine disrupting chemicals and autism spectrum disorder in offspring
Authors: Marí-Bauset Salvador , Peraita-Costa Isabel , Donat-Vargas Carolina , Llopis-González Agustín , Marí-Sanchis Amelia , Llopis-Morales Juan , Morales Suárez-Varela María 
Published: August 2021

Epidemiological studies, which can have inherent methodological limitations, are used to study the relation between endocrine disrupting chemicals and autism spectrum disorder. The objective is to systematically review the treatment of methodological limitations and assess the quality and strength of the findings in the available literature. The quality and strength of the evidence were evaluated using the Navigation Guide Systematic Review Methodology. The overall quality and strength of the available studies were “moderate” and “limited,” respectively. Risk of bias due to the methodological limitations regarding the exclusion of potential confounding factors and the lack of accuracy of exposure assessment methods were the most prevalent and were also considered to arrive at these results. The omnipresence of endocrine disrupting chemicals, their persistence and bioaccumulation, and the biological plausibility of the association between prenatal exposure to these and later development of autism spectrum disorder highlight the need to carry out well-designed epidemiological studies that overcome the methodological limitations observed in the currently available literature in order to be able to inform public policy to prevent exposure to these potentially harmful chemicals. Lay abstract Autism spectrum disorders comprise a complex group with many subtypes of behaviorally defined neurodevelopmental abnormalities in two core areas: deficits in social communication and fixated, restricted, repetitive, or stereotyped behaviors and interests each with potential unique risk factors and characteristics. The underlying mechanisms and the possible causes of autism spectrum disorder remain elusive and while increased prevalence is undoubtable, it is unclear if it is a reflection of diagnostic improvement or emerging risk factors such as endocrine disrupting chemicals. Epidemiological studies, which are used to study the relation between endocrine disrupting chemicals and autism spectrum disorder, can have inherent methodological challenges that limit the quality and strength of their findings. The objective of this work is to systematically review the treatment of these challenges and assess the quality and strength of the findings in the currently available literature. The overall quality and strength were “moderate” and “limited,” respectively. Risk of bias due to the exclusion of potential confounding factors and the lack of accuracy of exposure assessment methods were the most prevalent. The omnipresence of endocrine disrupting chemicals and the biological plausibility of the association between prenatal exposure and later development of autism spectrum disorder highlight the need to carry out well-designed epidemiological studies that overcome the methodological challenges observed in the currently available literature in order to be able to inform public policy to prevent exposure to these potentially harmful chemicals and aid in the establishment of predictor variables to facilitate early diagnosis of autism spectrum disorder and improve long-term outcomes.