Autism Spectrum Disorders in Relation to Distribution of Hazardous Air Pollutants in the San Francisco Bay Area

Abstract

ObjectiveTo explore possible associations between autism spectrum disorders (ASD) and environmental exposures, we linked the California autism surveillance system to estimated hazardous air pollutant (HAP) concentrations compiled by the U.S. Environmental Protection Agency.MethodsSubjects included 284 children with ASD and 657 controls, born in 1994 in the San Francisco Bay area. We assigned exposure level by census tract of birth residence for 19 chemicals we identified as potential neurotoxicants, developmental toxicants, and/or endocrine disruptors from the 1996 HAPs database. Because concentrations of many of these were highly correlated, we combined the chemicals into mechanistic and structural groups, calculating summary index scores. We calculated ASD risk in the upper quartiles of these group scores or individual chemical concentrations compared with below the median, adjusting for demographic factors.ResultsThe adjusted odds ratios (AORs) were elevated by 50% in the top quartile of chlorinated solvents and heavy metals [95% confidence intervals (CIs), 1.1–2.1], but not for aromatic solvents. Adjusting for these three groups simultaneously led to decreased risks for the solvents and increased risk for metals (AORs for metals: fourth quartile = 1.7; 95% CI, 1.0–3.0; third quartile = 1.95; 95% CI, 1.2–3.1). The individual compounds that contributed most to these associations included mercury, cadmium, nickel, trichloroethylene, and vinyl chloride.ConclusionsOur results suggest a potential association between autism and estimated metal concentrations, and possibly solvents, in ambient air around the birth residence, requiring confirmation and more refined exposure assessment in future studies.

Exposure to Air Pollution From Traffic and Neurodevelopmental Disorders in Swedish Twins

“…Windham et al (2006) reported a positive relation between the distribution of hazardous air pollutants at birth addresses and ASD among children in California. Other studies in California found that living close to freeways and traffic-related air pollution in mother's late pregnancy or child's first year of life was associated with an increased risk for autism (Volk et al, 2011(Volk et al, , 2013.…”

“…Maternal smoking correlates with socio-economic factors such as education and income (Kabir et al, 2011;Laaksonen et al, 2005) and may contribute to this association. The earlier studies (Calderon-Garciduenas et al, 2011;Guxens et al, 2012;Siddique et al, 2011;Volk et al, 2011;Vrijheid et al, 2012;Windham et al, 2006) Odds ratios and 95% confidence intervals of neurodevelopmental outcomes by residential address-based NO x (black circles) and PM 10 (black hollow diamonds) levels. The spikes represent odds ratios for outcomes of interest and cap lines indicate 95% confidence intervals.…”

Advances in behavioral genetics: mouse models of autism

“…A recent study determined that rates of autism spectrum disorders were higher in areas with greater hazardous air pollutant concentrations, which included the heavy metal mercury. 276 Overall, these findings suggest that further work in animal models for prenatal neurotoxin exposure, such as organophosphate pesticides or mercury, might provide information on the interaction between genetic predisposition and environmental challenge in autism.…”

“…275,276 A recent review by Herbert et al 7 identified 135 genes that have been shown to mediate responses to environmental challenge, and that are located within autism linkage regions. The genes were derived from several databases, including the National Institute of Environmental Health Science (NIEHS) Environmental Genome Project, the Comparative Toxicogenomics Database and the Program for Genomic Applications SeattleSNPs Database (focused on genes mediating inflammatory responses).…”

Maternal Exposure to Isobutyl-Paraben Impairs Social Recognition in Adult Female Rats

“…For example, the average prevalence of ASDs among children aged 8 years increased by 57% across 10 locations in the United States from 2002 to 2006. While genetic factors are clearly important, [23,31] these increasing rates of ASDs suggest that environmental factors are involved in causing this developmental disorder [11,14,30,39].…”