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ENVIRONMENTAL EXPOSURE TO CHLORTETRACYCLINE AND NON-ATOPIC ASTHMA IN CHILDREN LIVING ON FARMS
Citation:
Svendsen, E., A. Naleway, S. Reynolds, P. Thorne, A. Stromquist, J. Merchant, AND C. Taylor. ENVIRONMENTAL EXPOSURE TO CHLORTETRACYCLINE AND NON-ATOPIC ASTHMA IN CHILDREN LIVING ON FARMS. Presented at American Thoracic Society Meeting, Seattle, WA, May 16-21, 2002.
Description:
Many studies have reported lower prevalence of childhood asthma and atopy in farming populations relative to urban. The Keokuk County Rural Health Study, a 20-year longitudinal prospective cohort study of the chronic effects of farming on health in 1,004 families from a completely rural Iowa county, found a high overall prevalence of childhood asthma: 16.3%, highest in farm children: 20.5%, compared with town and rural non-farm children. Atopy was lowest in farm children: 22.8%. A cross-sectional study was performed to identify any specific farm exposures associated with the increased prevalence of asthma in farm children. Many livestock, pesticide, and feed variables were analyzed individually. Bivariate analyses demonstrated that farm pesticide use, raising any livestock, having over 500 head, and raising hogs (but not cattle) were significantly associated with asthma. Currently using chlortetracycline antibiotic feed additives was strongly associated with asthma prevalence (crude Odds Ratio: 3.6, 95% CI 1.5-8.1). After adjusting for other known risk factors and multiple comparisons within homes, the latter association was still significant (adjusted Odds Ratio: 1.2, 95% CI 1.1-1.4), and greatest with non-atopic asthma (adjusted Odds Ratio: 1.4, 95% CI 1.2-1.6). The exposure metric of farmers cross-contaminating their homes with agricultural dusts, pesticides, and danders and children exposing themselves through hand-to-mouth activities is well established. Recent studies have demonstrated the immunomodulating effects of the tetracyclines, lending plausibility to the association we found. Many studies have previously documented non-atopic asthma in farmers. Our study supports the hypothesis of a protective effect of farming on atopy, and raises the possibility that environmental exposure to tetracyclines may be associated with the development of non-atopic asthma in children. NIOSH U07/CCU706145. This abstract does not necessarily represent EPA policy.