| Asthma and Farm Exposures in a Cohort of Rural Iowa Children James A. Merchant,1 Allison
L. Naleway,2 Erik R. Svendsen,3 Kevin M. Kelly,1 Leon
F. Burmeister,4 Ann M. Stromquist,1 Craig D.
Taylor,1 Peter S. Thorne,1 Stephen J. Reynolds,5 Wayne
T. Sanderson,1 and Elizabeth A. Chrischilles6 1Department of Occupational and Environmental Health, University
of Iowa College of Public Health, Iowa City, Iowa, USA; 2Center
for Health Research, Kaiser Permanente Northwest, Portland, Oregon, USA; 3National
Health and Environmental Effects Research Laboratory, Human Studies Division,
Epidemiology and Biomarkers Branch, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, USA; 4Department of Biostatistics,
University of Iowa College of Public Health, Iowa City, Iowa, USA; 5Department
of Environmental and Radiological Health Sciences, Colorado State University
College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado,
USA; 6Department of Epidemiology, University of Iowa College of
Public Health, Iowa City, Iowa, USA Abstract
Epidemiologic studies of farm children are of international interest because farm children are less often atopic, have less allergic disease, and often have less asthma than do nonfarm children--findings consistent with the hygiene hypothesis. We studied a cohort of rural Iowa children to determine the association between farm and other environmental risk factors with four asthma outcomes: doctor-diagnosed asthma, doctor-diagnosed asthma/medication for wheeze, current wheeze, and cough with exercise. Doctor-diagnosed asthma prevalence was 12%, but at least one of these four health outcomes was found in more than a third of the cohort. Multivariable models of the four health outcomes found independent associations between male sex (three asthma outcomes) , age (three asthma outcomes) , a personal history of allergies (four asthma outcomes) , family history of allergic disease (two asthma outcomes) , premature birth (one asthma outcome) , early respiratory infection (three asthma outcomes) , high-risk birth (two asthma outcomes) , and farm exposure to raising swine and adding antibiotics to feed (two asthma outcomes) . The high prevalence of rural childhood asthma and asthma symptoms underscores the need for asthma screening programs and improved asthma diagnosis and treatment. The high prevalence of asthma health outcomes among farm children living on farms that raise swine (44.1%, p = 0.01) and raise swine and add antibiotics to feed (55.8%, p = 0.013) , despite lower rates of atopy and personal histories of allergy, suggests the need for awareness and prevention measures and more population-based studies to further assess environmental and genetic determinants of asthma among farm children. Key words: agricultural occupational exposures, ammonia, animal feeding operations, asthma, asthma diagnosis and treatment, asthma health care policy, asthma school screening, asthma underdiagnosis, asthma undertreatment, children, chronic wheeze, cough with exercise, farming, genetic selection, hydrogen sulfide, hygiene hypothesis, odor, rural. Environ Health Perspect 113:350-356 (2005) . doi:10.1289/ehp.7240 available via http://dx.doi.org/ [Online 7 December 2004]
Address correspondence to J.A. Merchant, University of Iowa College of Public Health, E220H1 General Hospital, Iowa City, IA 52242 USA. Telephone: (319) 384-5452. Fax: (319) 384-5455. E-mail: james-merchant@uiowa.edu The authors acknowledge the many contributions of the Keokuk County Rural Health Study staff. This work was supported by National Institute for Occupational Safety and Health (NIOSH) grant 5 R01/CCR714364 and NIOSH-funded grant U07/CCU706145 to the Great Plains Center for Agricultural Health. These findings do not necessarily represent the U.S. Environmental Protection Agency. The authors declare they have no competing financial interests. Received 6 May 2004 ; accepted 7 December 2004.
The full version of this article is available for free in HTML or PDF formats. |
