Odor from industrial hog farming operations and mucosal immune function in neighbors

The authors evaluated whether exposure to malodor from industrial hog farming operations has a psychophysiologically mediated immunosuppressive effect on secretory immunoglobulin A (sIgA) in neighbors. Fifteen adults living within 2.4 km (1.5 mi) of at least one hog farming operation rated odor intensity on a 9-point scale and provided saliva samples twice daily for two weeks. The authors used hierarchical regression to model the association between reported odor and sIgA; study participants were their own controls. The natural log of sIgA concentration and secretion rate declined, on average, 0.058 (0.032) and 0.116 (0.103), respectively, for each incremental 1-unit increase in reported odor from 4 to 9, adjusted for time of day, suggesting reduced levels of sIgA in response to moderate or high odor. Findings support the hypothesized immunosuppressive effect of malodor on mucosal immunity and provide preliminary data useful in understanding health effects related to malodor from industrial hog farming operations.