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BACKGROUND: Little is known about environmental causes and contributing factors for autism. Basic science and epidemiologic research suggest diat oxidative stress and inflammation may play a role in disease development. Traffic-related air pollution, a common exposure with established effects on diese padiways, contains substances found to have adverse prenatal effects.
OBJECTIVES: We examined die association berween autism and proximity of residence to freeways and major roadways during pregnancy and near die time of delivery, as a surrogate for air pollution exposure.
METHODS: Data were from 304 autism cases and 259 typically developing controls enrolled in die Childhood Autism Risks from Genetics and the Environment (CHARGE) study. The mother's address recorded on the birth certificate and trimester-specific addresses derived from a residential history obtained by questionnaire were geocoded, and measures of distance to freeways and major roads were calculated using ArcGIS software. Logistic regression models compared residential proximity to freeways and major roads for autism cases and typically developing controls.
RESULTS: Adjusting for sociodemographic factors and maternal smoking, maternal residence at the time of delivery was more likely be near a freeway (< 309 m) for cases than for controls [odds ratio (OR) = 1.86; 95% confidence interval (CI), 1.04-3.45]. Audsm was also associated with residential proximity to a freeway during die third trimester (OR = 2.22; CI, 1.16-4.42). After adjustment for socioeconomic and sociodemographic characteristics, these associations were unchanged. Living near other major roads at birth was not associated with autism.
CONCLUSIONS: Living near a freeway was associated with autism. Examinadon of associadons with measured air pollutants is needed.
KEY WORDS: autism, epidemiology', gene-environment interaction, roadway proximity, traffic emissions. Environ Health Perspect 119:873-877 (2011). doi: 10.1 289/ehp. 1002835 [Online 16 December 2010]
Autism is a developmental disorder characterized by significant deficits in social interaction and communication, accompanied by repetitive behaviors (American Psychiatric Association 2000). Data from family and twin studies have long supported the role of genetics in autism etiology (Abrahams and Geschwind 2008; Mühle et al. 2004). Results from linkage, copy number variation, and genomewide association studies further support the importance of genetic risk in this disease (Abrahams and Geschwind 2008; Ma et al. 2009; Wang et al. 2009). Over the last 10 years, the prevalence of diagnoses of autism, and all...