Residential Proximity to Freeways and Autism in the CHARGE Study

Department of Preventive Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, Children's Hospital Los Angeles, University of Southern California, Los Angeles, California 90033, USA.
Environmental Health Perspectives (Impact Factor: 7.98). 12/2010; 119(6):873-7. DOI: 10.1289/ehp.1002835
Source: PubMed


Little is known about environmental causes and contributing factors for autism. Basic science and epidemiologic research suggest that oxidative stress and inflammation may play a role in disease development. Traffic-related air pollution, a common exposure with established effects on these pathways, contains substances found to have adverse prenatal effects.
We examined the association between autism and proximity of residence to freeways and major roadways during pregnancy and near the time of delivery, as a surrogate for air pollution exposure.
Data were from 304 autism cases and 259 typically developing controls enrolled in the 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.
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]. Autism was also associated with residential proximity to a freeway during the 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.
Living near a freeway was associated with autism. Examination of associations with measured air pollutants is needed.

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    • "This connection is of particular interest as previous studies from our research group indicate that children with autism are more immune-sensitive to environmental exposure (Ashwood et al., 2009). Further studies have also demonstrated a relationship between proximity to freeways during early development and ASD (Volk et al., 2011, 2013). Thus, differences in cytokine profiling in the context of asthma could be a product of particular environmental exposures. "
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    • "Several of these studies have demonstrated associations between ASD and prenatal or perinatal air concentrations of various air pollutants, including particulate matter (Becerra et al., 2013; Kalkbrenner et al., 2010, 2014; Roberts et al., 2013; Talbott et al., 2015; Windham et al., 2006). Additionally, proximity to sources of airborne pollutants, including industrial facilities (Palmer et al., 2009), agricultural pesticides (Shelton et al., 2014), and high-traffic roadways (Volk et al., 2011), have been associated with ASD diagnosis and school-reported administrative prevalence , respectively. Based on results from these studies, observed relationships should be further investigated on a larger scale using highly reliable data. "
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    • "population based case-control studies from the Childhood Autism Risks from Genetics and the Environment (CHARGE) study. The first study population (Volk et al., 2011) consisted of 304 autism cases and 259 typically developing controls. In addition to the address on the birth certificate, a detailed residential history from three months before conception until the current address was obtained by personal interview. "
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