Early-life Farm Exposures and Adult Asthma and Atopy in the Agricultural Lung Health Study

Publication date: Available online 12 November 2016
Source:Journal of Allergy and Clinical Immunology
Author(s): John S. House, Annah B. Wyss, Jane A. Hoppin, Marie Richards, Stuart Long, David M. Umbach, Paul Henneberger, Laura E. Beane Freeman, Dale P. Sandler, Elizabeth Long O'Connell, Christie Barker Cummings, Stephanie J. London
BackgroundPrevious 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.ObjectiveTo examine associations between early-life farming exposures and current asthma and atopy in an older adult US farming population.MethodsWe analyzed data from 1,746 farmers and 1,555 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 one of ten 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 (1,198 cases and 2,031 non-cases) or atopy (578 cases and 2,526 non-cases).ResultsExposure 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% Confidence Interval=0.48-0.74) and remained significant in models with correlated early-life exposures including early childhood farm animal contact and raw milk consumption.ConclusionsIn 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.

Teaser

Early-life farming exposures were associated with reduced odds of atopy, but not asthma, in an older adult US farming population, suggesting that the protective association of early-life farming exposures on atopy endures across the life-course.


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