Malodor from industrial hog operations, stress, negative mood, and secretory immune function in nearby residents

by Horton, Rachel Avery, Ph.D., THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL, 2007, 132 pages; 3289022


In North Carolina, and throughout the United States, pork production has industrialized over the last 20 years, with the majority of hogs now raised in confinement houses and their waste stored either beneath the confinement houses or in open-air lagoons until it is sprayed via irrigation systems on nearby fields as fertilizer. People living near these industrial farms report frequent exposure to malodor and adverse effects on their health and quality of life. Evaluated here is the hypothesis that malodor is an environmental stressor that, when appraised as such, exerts an immunosuppressive effect on secretory immune function in neighbors.

Seventy-one study participants in eastern North Carolina collected data twice daily for approximately 2 weeks. They reported the intensity of malodor from the hog operation(s) on a 9-point scale where 0 = no odor and 8 = extreme odor. They also rated feelings of stress/annoyance, anxiety, unhappiness, anger, and confusion on the same 9-point scale, and collected whole, unstimulated saliva samples for secretory immunoglobulin A (sIgA) analysis. Data were analyzed using multilevel models, appropriate for analysis of longitudinal data. Reported stress and negative mood appeared to be associated with malodor; odds ratios for a 1-unit change on the odor scale ranged from 1.4 to 1.7. The effects of malodor, stress, and mood on sIgA secretion were mixed; they did not appear to have an overall effect on sIgA, though there was some evidence of an effect in particular subgroups of the study population. Malodor from industrial hog operations does appear to affect stress and negative mood in neighbors, but sIgA may not be a useful marker of its physiologic effect.

AdviserSteve Wing
Source TypeDissertation
SubjectsPublic health; Epidemiology
Publication Number3289022

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