ORGANIC DUST EXPOSURES FROM WORK IN DAIRY BARNS

Environmental surveys were conducted in 85 barns, predominantly dairy, in central Wisconsin to characterize exposures to organic dusts and d ust constituents from routine barn work. Environmental analytes includ ed airborne dusts (total, inhalable inlet, and respirable), particle s ize distributions, endotoxins, total spore and bacteria counts, viable bacteria and fungi, histamine, cow urine antigen, mite antigen, ammon ia, carbon dioxide, and hydrogen sulfide. The geometric mean (GM) conc entration of airborne dusts include area total, 0.74 mg/m(3); personal inhalable inlet, 1.78 mg/m(3); and area respirable, 0.07 mg/m(3). Via ble bacteria and fungi, spores, endotoxins, histamine, cow urine antig en, and mite antigen were quantifiable constituents of these organic d usts and potential respiratory exposure hazards from routine dairy bar n work. Endotoxin concentrations from the inhalable inlet samples rang ed from 25.4 endotoxin units per cubic meter of air (EU/m(3)) to 34,80 0 EU/m(3). The GM endotoxin concentration from these samples, 647 EU/m (3), exceeds estimated threshold exposure levels for respiratory healt h effects. Ammonia was a common irritant quantified in most dairy barn s. There were significant correlations between the concentrations of o rganic dusts and certain dust constituents, although in most instances these correlations were not strong. These sampling results demonstrat e the complex nature of organic dusts and provide quantitative descrip tion of the exposures to toxic and immunogenic dust constituents durin g routine barn work.