Associations of Autism Spectrum Disorder with PM_2.5 Components: A Comparative Study Using Two Different Exposure...

Area of Science:

• Environmental Health
• Epidemiology
• Pediatric Health

Background:

• Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with increasing prevalence.
• Prenatal environmental exposures, including air pollution, are hypothesized to play a role in ASD etiology.
• Fine particulate matter (PM_2.5) is a major air pollutant with diverse chemical compositions.

Purpose of the Study:

• To investigate the association between prenatal exposure to specific fine particulate matter (PM_2.5) components and autism spectrum disorder (ASD).
• To compare exposure estimates from two distinct modeling approaches for PM_2.5 components.
• To examine the impact of exposure timing during pregnancy on ASD risk.

Main Methods:

• Retrospective cohort study of 318,750 mother-child pairs in Southern California (2001-2014).
• ASD cases identified via ICD codes, followed until age five.
• Prenatal exposure to PM_2.5 components (EC/BC, OM, NO₃^-, SO₄^2-) estimated using source-oriented chemical transport and hybrid models.

Main Results:

• ASD was associated with pregnancy-average PM_2.5, elemental/black carbon (EC/BC), organic matter (OM), and sulfate (SO₄^2-) from both models.
• Associations were strongest for EC/BC and OM in the first and second trimesters, and SO₄^2- in the third trimester.
• EC/BC, OM, and SO₄^2- effects were robust to adjustment for other components and PM_2.5.

Conclusions:

• Specific PM_2.5 components, particularly EC/BC and OM, are associated with increased ASD risk following prenatal exposure.
• The timing of exposure during gestation may differentially impact ASD risk.
• Utilizing multiple exposure models and a weight-of-evidence approach is recommended for future air pollution health studies.