RESPIRATORY DYSFUNCTION IN SWINE PRODUCTION FACILITY WORKERS - DOSE-RESPONSE RELATIONSHIPS OF ENVIRONMENTAL EXPOSURES AND PULMONARY-FUNCTION

Human respiratory health hazards for people working in livestock confi nement buildings have been recognized since 1974. However, before comp rehensive control programs can be implemented, more knowledge is neede d of specific hazardous substances present in the air of these buildin gs, and at what concentrations they are harmful. Therefore, a medical epidemiological and exposure-response study was conducted on 207 swine producers using intensive housing systems (108 farms). Dose-response relationships between pulmonary function and exposures are reported he re. Positive correlations were seen between change in pulmonary functi on over a work period and exposure to total dust, respirable dust, amm onia, respirable endotoxin, and the interactions of age-of-producer an d dust exposure and years-of-working-in-the-facility and dust exposure . Relationships between baseline pulmonary function and exposures were not strong and therefore, not pursued in this study. The correlations between exposure and response were stronger after 6 years of exposure . Multiple regression models were used to identify total dust and ammo nia as the two primary environmental predictors of pulmonary function decrements over a work period. The regression models were then used to determine exposure concentrations related to pulmonary function decre ments suggestive of a health hazard. Total dust concentrations greater than or equal to 22.8 mg/m(3) were predictive of a work period decrem ent of greater than or equal to 10% in FEV(1). Ammonia concentrations of greater than or equal to 7.5 ppm were predictive of a greater than or equal to 3% work period decrement in FEV(1). These predictive conce ntrations were similar to a previous dose-response study, which sugges ted 2.5 mg/m(3) of total dust and 7 ppm of NH3 were associated with si gnificant work period decrements. Therefore, dust greater than or equa l to 2.8 mg/m(3) and ammonia greater than or equal to 7.5 ppm should b e considered reasonable evidence for guidelines regarding hazardous ex posure concentrations in this work environment. (C) 1995 Wiley-Liss, I nc.