Farming practices and the respiratory health risks of swine confinement buildings

Abstract

This study investigated whether clean swine confinement buildings (SCB) are less harmful to the respiratory system than older and dirtier facilities. Eight healthy volunteers were exposed for 4 h, at 1 week intervals, to eight SCB representing the widest possible range of cleanliness. Each volunteer and a technician rated the SCB for cleanliness from 1-10, 1 being the cleanest possible. Airborne dust, bacteria, endotoxin levels, molds, and ammonia were measured. For each volunteer measured, before and after each exposure, forced expiratory flows (forced expiratory volume in one second (FEV1), and forced vital capacity), white cells in nasal wash and venous blood, and nasal lavage levels of interleukin (IL)-8 and serum levels of IL-6. A methacholine challenge was obtained at baseline and following each exposure. Cleanliness scores ranged 1.58.25. Mean airborne levels were: dust 3.54 mg·m-3 bacteria 4.25 x 105 CFU·m-3; endotoxins 404 EU·m-3; molds 883 CFU·m-3; ammonia 20.7 parts per million (ppm). Expiratory flows decreased after exposure (FEV1 from 4.8±0.7 to 4.4±0.7, p<0.001), neutrophils in the nasal wash and white blood cells increased (28.5±37 to 424±207 x 103, 5.4±1.0 to 7.4±1.7 x 109 cells·mL-1 respectively), IL-8 increased from 158±311 to 2679±639 pg·mL-1, IL-6 from 0.15±0.26 to 2.34±0.92 pg·mL-1, (p<0.001). All SCB were similarly harmful. In conclusion, modern farming has not succeeded in making swine confinement buildings inoffensive to exposed subjects.