title: Early-life farm exposures and adult asthma and atopy in the Agricultural Lung Health Study.
abstract: BACKGROUND
  Previous studies, mostly from Europe, suggest that early-life farming exposures protect against childhood asthma and allergy; few data exist on asthma and allergy in adults.
  
  
  OBJECTIVE
  We sought to examine associations between early-life farming exposures and current asthma and atopy in an older adult US farming population.
  
  
  METHODS
  We analyzed data from 1746 farmers and 1555 spouses (mean age, 63) from a case-control study nested within the Agricultural Health Study. Current asthma and early-life farming exposures were assessed via questionnaires. We defined atopy based on specific IgE > 0.70 IU/mL to at least 1 of 10 allergens measured in blood. We used logistic regression, adjusted for age, sex, race, state (Iowa or North Carolina), and smoking (pack years), to estimate associations between early-life exposures and asthma (1198 cases and 2031 noncases) or atopy (578 cases and 2526 noncases).
  
  
  RESULTS
  Exposure to the farming environment in utero and in early childhood had little or no association with asthma but was associated with reduced odds of atopy. The strongest association was seen for having a mother who performed farm activities while pregnant (odds ratio, 0.60; 95% CI, 0.48-0.74) and remained significant in models with correlated early-life exposures including early childhood farm animal contact and raw milk consumption.
  
  
  CONCLUSIONS
  In a large US farming population, early-life farm exposures, particularly maternal farming activities while pregnant, were strongly associated with reduced risk of atopy in adults. These results extend previous work done primarily on childhood outcomes and suggest that protective associations of early-life farming exposures on atopy endure across the life course.
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC.
authors.forename: John S
authors.initials: JS
authors.lastname: House
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC.
authors.forename: Annah B
authors.initials: AB
authors.lastname: Wyss
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC; Department of Biological Sciences, Center for Human Health and the Environment, North Carolina State University, Raleigh, NC.
authors.forename: Jane A
authors.initials: JA
authors.lastname: Hoppin
authors.affiliation: Westat, Durham, NC.
authors.forename: Marie
authors.initials: M
authors.lastname: Richards
authors.affiliation: Westat, Durham, NC.
authors.forename: Stuart
authors.initials: S
authors.lastname: Long
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC.
authors.forename: David M
authors.initials: DM
authors.lastname: Umbach
authors.affiliation: Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV.
authors.forename: Paul K
authors.initials: PK
authors.lastname: Henneberger
authors.affiliation: Occupational and Environmental Epidemiology Branch, National Cancer Institute, Bethesda, Md.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Beane Freeman
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC.
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.affiliation: Epidemiology Center, Public Health Sciences, Social & Scientific Systems, Inc, Durham, NC.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Long O'Connell
authors.affiliation: Epidemiology Center, Public Health Sciences, Social & Scientific Systems, Inc, Durham, NC.
authors.forename: Christie
authors.initials: C
authors.lastname: Barker-Cummings
authors.affiliation: Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC. Electronic address: london2@niehs.nih.gov.
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: London
mesh_terms: D000368:Aged; D001249:Asthma / Q000453:epidemiology*; D016022:Case-Control Studies; D004781:Environmental Exposure; D000072480:Farms; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000097:blood / Q000453:epidemiology*; D007073:Immunoglobulin E / Q000097:blood; D007484:Iowa / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D016017:Odds Ratio; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology
chemical_list: D007073:Immunoglobulin E
keywords: Agriculture; IgE; agricultural workers' diseases; allergy and immunology; asthma; hygiene hypothesis; prenatal exposure delayed effects