Quantification of odors and odorants from swine operations in North Carolina

A total of 331 different VOCs and fixed gases from swine facilities in Nort h Carolina were identified by gas chromatography and mass spectrometry (GC/ MS). Of these. 203 were found in air samples adsorbed onto Tenax((R)), 112 were found in air samples adsorbed onto cotton material, and 167 different compounds were identified in the lagoon samples. The compounds identified w ere diverse, and included many acids, alcohols, aldehydes, amides, amines, aromatics, esters, ethers, fixed gases, halogenated hydrocarbons, hydrocarb ons, ketones, nitriles, other nitrogen-containing compounds, phenols, sulfu r-containing compounds, steroids, and other compounds. The vast majority of these compounds were present at concentrations below published odor and ir ritation thresholds. Yet human assessments indicated that odors land irrita nt sensations) in the immediate vicinity of the swine houses land even at d istances beyond 1000 ft) were strong. Comparison of the findings from chemi cal and human assessments points to the importance of the cumulative effect s of hundreds of compounds in producing odor and irritation downwind of swi ne operations. Many GC peaks from the samples were too small to allow ident ification of the compounds, but their presence may also contribute signific antly to the odor and irritation. Several methodological difficulties were associated with the human odor assessments. Odorous air evaluated in the fi eld was simultaneously collected in Tedlar((R)) bags for evaluation in the laboratory; however, intensity ratings in the held were higher than those i n the laboratory. This is due to the fact that organic dust (dried fecal ma terial and feed) adheres to Tedlar((R)) bags and the tubing of collection/d elivery systems; therefore, only VOCs from the vapor phase (but not the dus t) reach the nose of the panelists in sniffing air samples obtained in Tedl ar((R)) bags. Future collection and measurement techniques need to be devel oped that can evaluate odors from dust and vapor phases simultaneously in t he laboratory. Dispersion models also need to be developed that account acc urately for odor intensities downwind of animal operations. Finally. safety standards for odor exposures need to be determined that consider the risk of simultaneous exposure to hundreds of low level compounds. (C) 2001 Elsev ier Science B.V. All rights reserved.