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MB Sample ID: SA273815
Local Sample ID: | 42_1 |
Subject ID: | SU002827 |
Subject Type: | Mammal |
Subject Species: | Rattus norvegicus |
Taxonomy ID: | 10116 |
Age Or Age Range: | 12 weeks |
Gender: | Male |
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Treatment:
Treatment ID: | TR002836 |
Treatment Summary: | Samples were received frozen in aliquots of lung tissue. Prior to analysis, samples were thawed and prepared for HRM analysis using the standard protocols described in the Sample Preparation section. Eucalyptus was selected as the biomass of interest due to its prevalence and likeness of chaparral ecosystems present in Southern California and Australia, areas that have experienced growing severity of wildland fires in recent years. To mimic the deployment of common fire line shifts, rats were exposed to whole-body eucalyptus smoke over the course of two weeks. Exposure occurred for 4 consecutive days on week 1, followed by a 3-day break, and 3 subsequent days of smoke exposure on week 2. An n = 24 rats were randomized by weight into three groups based on body weight (n = 8 / group): filtered air, low smoke, and high smoke concentrations. The smoke exposures were set to a target CO of 10 ppm for the low smoke group and 20 ppm for the high smoke group. These concentrations bracket the National Wildfire Coordinating Group’s recommended exposure limit of 15 ppm, which is lower than the 35 ppm limit set by the National Institute for Occupational Safety and Health. Further, these concentrations were selected to avoid respiratory suppression and the potential for anti-inflammatory signaling from high concentrations of CO in the rodent. Eucalyptus smoke was generated in a quartz-tube furnace system set to a smoldering condition (~ 500°C) with a primary air flow at ~ 2 L/min. Additional details on the design of the tube furnace system can be found in Kim, et al. Generated smoke was diluted using a secondary air flow to maintain our target CO concentrations and was subsequently delivered to a whole-body inhalation chamber. CO and CO2 were continuously monitored using a nondispersive infrared analyzer (602 CO/CO2; CAI, Inc.) and nitrogen oxides were monitored using a chemiluminescent analyzer (42i NO/NO2/NOx; ThermoScientific). Environmental conditions in the chambers were measured in real-time using Dasylab Software (v.13.0; National Instruments). Particle size distribution within the exposure chamber was measured for 5 minutes at the mid-point of the exposure using an electrical low-pressure impactor (ELPI model 97-2E; Dekati Ltd.) and analyzed for surface area-weighted distributions (ELPIvi v.3.0; Dekati Ltd.). Final PM concentrations following each exposure was determined by gravimetrically weighing a glass-fiber filtered placed in the exhaust line of the quartz-tube furnace system before and after the combustion. Due to staffing limitations, VOCs were not able to be characterized for the specific exposures within this study. However, the chemicals found in eucalyptus smoke and concentration ranges generated in our tube furnace system can be found in Kim, et al. (36) and Kim, et al. Attributable to the length of the quartz tube used in our system, each daily exposure was limited to 1 hour. |