Exposure to antibiotic feed additives and asthma in U.S. farm children.
Svendsen-ER; Naleway-AL; Reynolds-SJ; Taylor-CD; Thorne-PS; Stromquist-AM; Merchant-JA
Am J Respir Crit Care Med 2003 Apr; 167(7):A155
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 cohort study of the chronic health effects of farming in 1,004 families, 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 asthma prevalence. Many farm variables were analyzed. Bivariate analyses found that several variables were significantly associated with asthma, including currently using chlortetracycline antibiotic feed additives (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 fanners cross-contaminating their homes with agricultural residues 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. 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. This abstract does not necessarily represent EPA policy.
Antibiotics; Farmers; Agricultural-industry; Agricultural-workers; Pulmonary-system-disorders; Respiratory-system-disorders; Exposure-levels; Risk-factors; Environmental-exposure
Abstract; Conference/Symposia Proceedings
American Journal of Respiratory and Critical Care Medicine, 2003 International Conferenence, The American Thoracic Society, Seattle, WA, May 16-21, 2003
University of Iowa, Iowa City, Iowa