Odors from sewage sludge and livestock: Associations with self-reported health

Municipal waste water sludge contains microbes and toxicants and is commonly applied to land. Some neighbors of land application sites report sludge-associated malodors and illness. We evaluated sludge and livestock odors, 14 physical symptoms, and quality of life indicators reported by neighbors of fields applied with class-B sludge and residents of comparison areas with no sludge application, and measured concentrations of brominated flame retardants on pine needles as an indicator of sludge aerosol dispersal. 157 adults living near liquid sludge application sites, 85 near cake application sites, and 188 in comparison areas responded to a household survey. Sludge exposure was classified as none or faint vs. moderate, strong, or very strong sludge odor separately for residents of liquid and cake application vs. comparison areas. Livestock odor was classified as none or faint vs. moderate, strong, or very strong. We identified upper respiratory, lower respiratory, gastrointestinal, and skin symptom factors by principle components analysis. Generalized estimating equations (GEE) linear models were used to compare factor scores for sludge and livestock odor adjusted for race, gender, education, smoking, passive smoking, and odors from burning and agricultural chemicals. Adjusted factor scores for lower respiratory symptoms (standard error) were 0.28±0.19 higher among residents who reported moderate to very strong odor from liquid sludge than in comparison areas, and 0.28±0.11 higher among residents who reported moderate to very strong livestock odor compared to no or faint livestock odor. Factor scores for skin symptoms were 0.27±0.21 higher for participants who reported moderate to very strong liquid sludge odor. Other factor scores were similar between groups. GEE logistic models of specific symptoms suggest that wheezing contributes most to the association of lower respiratory symptoms with liquid sludge, and that difficulty breathing, cough and wheezing contribute most to its association with livestock odor.