The design, construction, and operation of a whole-body inhalation chamber for use in avian toxicity studies

摘要

Environmental risk assessments are broadening to include evaluations of avian species exposed to gaseous and particulate materials (Mineau, 2002b; Irvine, 2004; Carmalt, 2005). Since the avian respiratory tract is fundamentally different from the respiratory tract of rodents, the effects of gaseous materials on birds cannot validly be extrapolated from data derived from rodent exposure studies (Briant & Driver, 1992; Brown et al., 1997). To address the lack of avian-specific lowest observable effect levels used to calculate reference concentrations for airborne pollutants, a system was designed to facilitate research on inhalation toxicology in small birds. Birds have long been used as early indicators of poor air quality (Brown et al., 1997), and various chambers have been designed for head only exposures of larger birds (Briant & Driver, 1992). Smaller birds with short tracheal lengths and hooked beaks however require less restrictive exposure apparatus, thus warranting the proposed design. The chamber described in this article was designed to accommodate a small falcon, the American kestrel, a species frequently used in toxicological risk assessments (Wiemeyer & Lincer, 1987a; Smits & Bortolotti, 2001; Bortolotti et al., 2003; Fisher et al., 2006). To accomplish this, a 41-L closed inhalation system capable of exposing 12 adult American kestrels was constructed primarily of galvanized steel, polyvinyl chloride, and copper tubing. Humidified air was passed over the birds and subsequently decontaminated by an activated carbon filter and released to a HEPA filtration system. The proposed inhalation chamber was successfully used in 2005 and 2006 to expose a total of 55 male American kestrels to benzene and toluene. Measurements of various biochemical endpoints associated with benzene and toluene toxicity allowed us to study the effects of airborne pollutants on small nondomesticated birds in a controlled laboratory setting.