Organic dust exposure from compost handling: Response of an animal model

Abstract

The objective of this investigation was to elucidate the pulmonary responses of an animal model to dust generated from leaf/wood compost which had caused a severe case of acute respiratory illness in an individual. Guinea pigs were exposed for 4 hr to 30 mg/m3 of aerosolized leaf/wood compost dust. Inhalation resulted in significant cellular activation and changes in pulmonary mechanics. Maximal elevation in breathing rate (increases 36%) was observed 12-18 hr postexposure. Similarly, maximal granulocyte infiltration (increases 1,600%) and activation of alveolar macrophages (increases 65%) occurred 18 hr postexposure. In contrast, maximal airway obstruction (increases 120%) occurred immediately after exposure and returned toward normal (increases 53%) by 18 hr postexposure. In several respects, the airway obstruction and pulmonary inflammation described in the animal model were comparable to the human response to compost dust. Therefore, this animal model may be useful in predicting the potential respiratory hazard associated with exposure to various organic dusts.

Insight into Pulmonary Gas Trapping as an Index of Airway Responses in Small Laboratory Animals

“…Further, the apparatus for measuring ELGV is much less expensive (hundreds of dollars) than the equipment for noninvasive or invasive pulmonary function measurements (tens of thousands of dollars) in small laboratory animals. Finally, investigators from academic [28,38,39], government [40], and pharmaceutical [27,41,42] laboratories have used the ELGV measurement to advance their research. Thus, I believe the ELGV measurement is a costeffective alternative approach for assessing in vivo airway mechanics in small laboratory animals and for examining novel therapies for treating human lung disease.…”

Pulmonary Reactions to Organic Dust Exposures: Development of an Animal Model

“…Similarly, exposure of guinea pigs to leaf/wood compost dust resulted in elevation of breathing rate, granulocyte infiltration, activation of alveolar macrophages, and airway obstruction, i.e., responses similar to those for cotton dust ( Table 1). As for cotton dust exposure, maximal breathing frequency was noted 12 to 18 hr after compost exposure, while maximal airway obstruction was found 0 hr postexposure (40).…”

“…In addition, particle size varied by less than 6% over this time, and the endotoxin content of the aerosolized dust remained constant. This dust exposure system has since been shown to be equally (38,39 (40,41).…”

“…In addition, the time courses of pulmonary responses of the guinea pig more closely mimic those of humans than do the rapid responses seen with rats and mice. Therefore, the guinea pig animal model (40,41). bGuii illness in workers.…”

“…Untreated cellulose did not alter the breathing frequency of guinea pigs; however, cellulose treated with Gram-negative bacteria, i.e., the source of endotoxin, mimicked the response to cotton dust. The response of the guinea pig model to organic dusts other than cotton dust has also been shown to be related to the relatively high endotoxin levels in these materials (40,41).…”