A Family Based Case Control Study on Perinatal Exposure to Ambient Air Pollution and Autism

A family-based case-control research was conducted to assess the correlations between autism and exposure to ambient air pollution throughout each trimester of pregnancy and the first few months of life. Autism spectrum disorder (ASD) is a neurological and developmental disorder that affects how people interact with others, communicate, learn, and behave. Although autism can be diagnosed at any age, it is described as a "developmental disorder" because symptoms generally appear in the first 2 years of life. Although the frequency of autism has significantly grown, nothing is known about its genesis. Several research have examined the impact of air pollution exposure on autism, despite hints that there may be links between it and neurodevelopmental diseases. However, the results are inconsistent. The possible role of unknown confounders is mainly blamed for this inconsistency. To minimize confounding effects, we evaluated the impact of air pollution exposure on autism using a family-based case-control study. Cases were 97 individuals with a diagnosis of autism born between 2009 and 2012 in Isfahan city, Iran. The controls were 54 individuals who did not have a previous history of autism and were cousins of the case person. The controls were matched with the autistic cases in terms of residential location and age range. For each trimester of pregnancy, carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and PM10 exposure were estimated using the inverse distance weighted method. The analysis indicates a significant association between CO exposure and autism in the second trimester (OR = 1.59;
= 0.046, 95% CI: 1.01 - 2.51) and entire pregnancy (OR = 2.02;
= 0.049, 95% CI: 1.01 - 2.95). Likewise, exposure to NO2 during the second trimester (OR = 1.17;
= 0.006, 95% CI: 1.04 - 1.31), third trimester (OR = 1.11;
= 0.046, 95% CI: 1.01 - 1.24), and entire pregnancy (OR = 1.27;
= 0.007, 95% CI: 1.07 - 1.51) were found to be associated with increased risk of autism.Overall, our study found higher exposure to CO and NO2, particularly during the second and third trimesters of pregnancy, was significantly associated with a higher risk of autism.