title: Parental exposures to occupational asthmagens and risk of autism spectrum disorder in a Danish population-based case-control study.
abstract: Environmental exposures and immune conditions during pregnancy could influence development of autism spectrum disorder (ASD) in offspring. However, few studies have examined immune-triggering exposures in relation to ASD. We evaluated the association between parental workplace exposures to risk factors for asthma ("asthmagens") and ASD.
  
  
  
  We conducted a population-based case-control study in the Danish population using register linkage. Our study population consisted of 11,869 ASD cases and 48,046 controls born from 1993 through 2007. Cases were identified by ICD-10 codes in the Danish Psychiatric Central Register. ASD cases and controls were linked to parental Danish International Standard Classification of Occupations (DISCO-88) job codes. Parental occupational asthmagen exposure was estimated by linking DISCO-88 codes to an asthma-specific job-exposure matrix.
  
  
  
  Our maternal analyses included 6706 case mothers and 29,359 control mothers employed during the pregnancy period. We found a weak inverse association between ASD and any maternal occupational asthmagen exposure, adjusting for sociodemographic covariates (adjusted OR: 0.92, 95% CI: 0.86-0.99). In adjusted analyses, including 7647 cases and 31,947 controls with employed fathers, paternal occupational asthmagen exposure was not associated with ASD (adjusted OR: 0.98, 95% CI: 0.92-1.05).
  
  
  
  We found a weak inverse association between maternal occupational asthmagen exposure and ASD, and a null association between paternal occupational exposure and ASD. We suggest that unmeasured confounding negatively biased the estimate, but that this unmeasured confounding is likely not strong enough to bring the effect above the null. Overall, our results were consistent with no positive association between parental asthmagen exposure and ASD in the children.
authors.affiliation: Department of Epidemiology and Wendy Klag Center for Autism and Developmental Disabilities, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe St, Baltimore, MD, 21205, USA. alison_singer@unc.edu.|Centre for Integrated Register-based Research, Aarhus University, Aarhus, Denmark. alison_singer@unc.edu.|Department of Epidemiology, University of North Carolina at Chapel Hill, CB #7435, Chapel Hill, NC, 27599, USA. alison_singer@unc.edu.
authors.forename: Alison B
authors.initials: AB
authors.lastname: Singer
authors.affiliation: Department of Environmental and Occupational Health, Department of Epidemiology and Biostatistics, the A.J. Drexel Autism Institute, Drexel University Dornsife School of Public Health, 3215 Market Street, Philadelphia, PA, 19104, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Burstyn
authors.affiliation: Centre for Integrated Register-based Research, Aarhus University, Aarhus, Denmark.|Department of Economics and Business, National Centre for Register-based Research, Aarhus University, Fuglesangs Allé 4, Building 2631, DK-8210, Aarhus V, Denmark.
authors.forename: Malene
authors.initials: M
authors.lastname: Thygesen
authors.affiliation: Centre for Integrated Register-based Research, Aarhus University, Aarhus, Denmark.|Department of Economics and Business, National Centre for Register-based Research, Aarhus University, Fuglesangs Allé 4, Building 2631, DK-8210, Aarhus V, Denmark.|Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.
authors.forename: Preben Bo
authors.initials: PB
authors.lastname: Mortensen
authors.affiliation: Department of Epidemiology and Wendy Klag Center for Autism and Developmental Disabilities, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe St, Baltimore, MD, 21205, USA.|Department of Mental Health, Johns Hopkins University Bloomberg School of Public Health, 624 N. Broadway, Baltimore, MD, 21205, USA.
authors.forename: M Daniele
authors.initials: MD
authors.lastname: Fallin
authors.affiliation: Centre for Integrated Register-based Research, Aarhus University, Aarhus, Denmark.|Department of Economics and Business, National Centre for Register-based Research, Aarhus University, Fuglesangs Allé 4, Building 2631, DK-8210, Aarhus V, Denmark.|Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.|Department of Public Health, Section for Epidemiology, Aarhus University, Bartholins Allé 2, Building 1260, DK-8000, Aarhus C, Denmark.
authors.forename: Diana E
authors.initials: DE
authors.lastname: Schendel
mesh_terms: D000328:Adult; D000393:Air Pollutants; D001249:Asthma; D000067877:Autism Spectrum Disorder / Q000453:epidemiology*; D016022:Case-Control Studies; D002648:Child; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D018811:Maternal Exposure; D016273:Occupational Exposure; D016017:Odds Ratio; D018812:Paternal Exposure; D012307:Risk Factors
chemical_list: D000393:Air Pollutants
keywords: Autism; Epidemiology; Neurodevelopment; Occupational asthma; Prenatal exposure