Association of prenatal exposure to air pollution with autism spectrum disorder

Pagalan L, Bickford C, Weikum W, Lanphear B, Brauer M, Lanphear N, Hanley GE, Oberlander TF, Winters M. Association of Prenatal Exposure to Air Pollution With Autism Spectrum Disorder. JAMA Pediatr. 2018 Nov 19. doi:10.1001/jamapediatrics.2018.3101. [Epub ahead of print]

Abstract

IMPORTANCE:

The etiology of autism spectrum disorder (ASD) is poorly understood, but prior studies suggest associations with airborne pollutants.

OBJECTIVE:

To evaluate the association between prenatal exposures to airborne pollutants and ASD in a large population-based cohort.

DESIGN, SETTING, AND PARTICIPANTS:

This population-based cohort encompassed nearly all births in Metro Vancouver, British Columbia, Canada, from 2004 through 2009, with follow-up through 2014. Children were diagnosed with ASD using a standardized assessment with the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Monthly mean exposures to particulate matter with a diameter less than 2.5 µm (PM2.5), nitric oxide (NO), and nitrogen dioxide (NO2) at the maternal residence during pregnancy were estimated with temporally adjusted, high-resolution land use regression models. The association between prenatal air pollution exposures and the odds of developing ASD was evaluated using logistic regression adjusted for child sex, birth month, birth year, maternal age, maternal birthplace, and neighborhood-level urbanicity and income band. Data analysis occurred from June 2016 to May 2018.

EXPOSURES:

Mean monthly concentrations of ambient PM2.5, NO, and NO2 at the maternal residence during pregnancy, calculated retrospectively using temporally adjusted, high-resolution land use regression models.

MAIN OUTCOMES AND MEASURES:

Autism spectrum disorder diagnoses based on standardized assessment of the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. The hypothesis being tested was formulated during data collection.

RESULTS:

In a cohort of 132 256 births, 1307 children (1.0%) were diagnosed with ASD by the age of 5 years. The final sample size for the PM2.5-adjusted model was 129 439 children, and for NO and NO2, it was 129 436 children; of these, 1276 (1.0%) were diagnosed with ASD. Adjusted odds ratios for ASD per interquartile range (IQR) were not significant for exposure to PM2.5 during pregnancy (1.04 [95% CI, 0.98-1.10] per 1.5 μg/m3 increase [IQR] in PM2.5) or NO2 (1.06 [95% CI, 0.99-1.12] per 4.8 ppb [IQR] increase in NO2) but the odds ratio was significant for NO (1.07 [95% CI, 1.01-1.13] per 10.7 ppb [IQR] increase in NO). Odds ratios for male children were 1.04 (95% CI, 0.98-1.10) for PM2.5; 1.09 (95% CI, 1.02-1.15) for NO; and 1.07 (95% CI, 1.00-1.13) for NO2. For female children, they were for 1.03 (95% CI, 0.90-1.18) for PM2.5; 0.98 (95% CI, 0.83-1.13) for NO; and 1.00 (95% CI, 0.86-1.16) for NO2.

CONCLUSIONS AND RELEVANCE:

In a population-based birth cohort, we detected an association between exposure to NO and ASD but no significant association with PM2.5 and NO2.

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In a large population cohort, researchers assessed the relationship between prenatal exposures to airborne pollutants and autism spectrum disorder (ASD). An association was found between exposure to nitric oxide (NO) and ASD but no significant association with PM2.5 and nitrogen dioxide (NO2) in a population-based birth cohort. Findings suggested that reducing the exposure of pregnant women to environmental NO might lead to a reduction in the incidence of ASD in their children.

Methods

This population-based cohort included almost all births in Metro Vancouver, British Columbia, Canada between 2004 and 2009, followed by 2014.

ASD was diagnosed in children using a standardized assessment with the Autism Diagnostic Interview–Revised and Autism Diagnostic Observation Schedule.

Monthly mean exposures to particulate matter smaller than 2.5 μm (PM2.5) in diameter, NO, and NO2 during pregnancy at maternal residence were estimated using temporally adjusted, high-resolution land use regression models.

Using logistic regression adjusted for child sex, birth month, birth year, maternal age, maternal birthplace, and neighborhood-level urbanicity and income band, the relationship between prenatal air pollution exposures and the odds of developing ASD was assessed.

The analysis of data took place between June 2016 and May 2018.

Using temporally adjusted, high-resolution land use regression models, mean monthly concentrations of ambient PM2.5, NO, and NO2 at the maternal residence during pregnancy, calculated retrospectively.

Main outcomes and measures included autism spectrum disorder diagnoses based on standardized assessment of the Autism Diagnostic Interview–Revised and Autism Diagnostic Observation Schedule.

The hypothesis was formulated during the collection of data.

Results

One thousand, three hundred seven children (1.0%) were diagnosed with ASD at the age of five years in a cohort of 132,256 births.

The final sample size for the PM2.5-adjusted model was 129,439 children and 129,436 children were diagnosed with ASD for NO and NO2, of whom 1276 (1.0%) were diagnosed.

Findings revealed that adjusted odds ratios for ASD per interquartile range (IQR) were not significant for exposure to PM2.5 during pregnancy (1.04 [95% CI, 0.98-1.10] per 1.5 μg/m3increase [IQR] in PM2.5) or NO2 (1.06 [95% CI, 0.99-1.12] per 4.8 ppb [IQR] increase in NO2), however, the odds ratio was significant for NO (1.07 [95% CI, 1.01-1.13] per 10.7 ppb [IQR] increase in NO).

It was noted that odds ratios for male children were 1.04 (95% CI, 0.98-1.10) for PM2.5; 1.09 (95% CI, 1.02-1.15) for NO; and 1.07 (95% CI, 1.00-1.13) for NO2.

Odds ratios for female children were 1.03 (95% CI, 0.90-1.18) for PM2.5; 0.98 (95% CI, 0.83-1.13) for NO; and 1.00 (95% CI, 0.86-1.16) for NO2.

https://www.mdlinx.com/journal-summaries/autism-spectrum-disorder-nitrogen-dioxide-nitric/2018/11/20/7549562?spec=neurology