Animal Exposure Chamber Research Articles

Facilities for diesel exhaust studies

It is the major intent of this report to examine the animal inhalation facilities at the EPA Health Effects Research Laboratory in Cincinnati, Ohio, associated with the exposure to the exhaust of diesel-powered equipment. The facility serves as a center for toxicologic evaluation, in relevant animal models, of potentially hazardous environmental pollutants from diesel engine exhaust. Briefly, the entire engine exhaust is mixed with filtered and conditioned air in a dilution tube. That diluted exhaust enters a large volume mixing chamber and a portion passes through dynamic flow irradiation chambers (to simulate sunlight) and is then conducted to animal exposure chambers. The system provides nonirradiated exhaust in the same concentration (directly from the mixing chamber) and also filtered, conditioned ambient air for control animal exposure. The major physical components of the diesel emission system include: air purifiers, animal exposure chambers, engine-dynamometers, irradiation chambers, monitoring instrumentation and data acquisition systems.

Physical characterization of diesel exhaust particles in exposure chambers

Since the deposition of particulate in the respiratory system is strongly influenced by particle size, a correct assessment of this parameter is important for any inhalation experiment studying the potential health effects of air pollutants. Measuring the distribution of particles according to their aerodynamic diameter and mechanical mobility diameter is crucial in analyzing the deposition of submicron particles in the lower respiratory system. Cascade impactor measurements of diluted diesel exhaust in 12.6 m 3 animal exposure chambers in the GMR Biomedical Science Department showed that the mass median aerodynamic diameter of the aerosol was 0.2 μm with 88% of the mass in particles smaller than 1 μm. Diffusion battery measurements showed that the mass median mechanical mobility diameter was about 0.11 μm. Transmission electron micrographs of particles deposited on chamber surfaces revealed both agglomerates and nearly spherical particles. The particles in these chambers are similar in size and shape to diesel particles described elsewhere. The flux of diesel particles to food surfaces was measured. Calculations of the expected daily dose by inhalation and by feeding showed that the “worst case” dose by feeding was only about one-tenth the dose by breathing.

A system for exposing animals to smoke generated in a steady-state fashion

A new method for exposing laboratory animals to polymer pyrolysis products is described. This method is advantageous in that dose may be accurately determined because the concentrations of pyrolysis products in the animal exposure chamber remain constant during exposure. Further, this apparatus was constructed from readily available materials.

The generation and evaluation of UICC asbestos clouds in animal exposure chambers.

When carrying out animal inhalation experiments using UICC asbestos it was found necessary to modify the dust cloud generation technique described by Timbrell, to obtain a stable, well-dispersed cloud at concentrations from 1 to 10 mg/m3. The MRE gravimetric dust sampler type 113A recommended by Timbrell as a routine monitoring instrument, was found to undersample at high chrysotile concentrations, and an alternative system was developed using a vertical elutriator. Fibre number counts of the clouds were obtained and correlated with mass concentrations. A Royco particle counter model 225 and Sibata digital dust indicator model AP.3 were tested, and their usefulness at the prevailing high concentrations assessed. Fibre length distributions for clouds of UICC chrysotile A, amosite and crocidolite asbestos are reported.

Design of A Large Scale Exposure and Sampling Facility for Street Level Auto Exhaust Emissions

A unique air handling facility was designed to introduce up to 12,000 cfm of street level air into laminar flow animal exposure chambers in an unaltered state except for the heating and cooling necessary in extreme weather to provide the animals with an habitable climate. The facility was built to determine the possible effect of street level exhaust emissions on the health of the general population. Another objective was to determine, by means of direct reading and recording instruments, the concentration of contaminants such as carbon monoxide, carbon dioxide, aerosols, nitrogen oxides, total oxidant, and unburned hydrocarbons.

Exposure of laboratory animals to atmospheric maganese from automotive emissions

Rats and hamsters were exposed eight hours/day for 56 consecutive days to automotive emissions containing increased concentrations of Mn particulate which resulted from the use of a fuel additive, methylcyclopentadienyl manganese tricarbonyl. The exhaust gases were generated by using a 1972 Chevrolet 350 CID engine dynamometer system. The exhaust was diluted and the average concentration of Mn particulate in the irradiated animal exposure chambers was approximately 117 μg/m 3. No gross changes in general condition or appearance were observed in any of the animals. Microscopic examination of tissues from the animals showed changes related to the exhaust emissions and no changes were found which could be solely attributed to the presence of Mn or MMT. Mn concentrations in the tissues from exposed animals were generally elevated.

Trace Metals in Asbestos Carcinogenesis

Concentrations of trace metals judged potentially carcinogenic were determined in samples of amosite, crocidolite, and chrysotiie. The samples included commercial material as shipped, milled and processed material as collected in animal exposure chambers, and International Union Against Cancer (UICC) reference samples. The metals determined were cobalt, nickel, chromium, manganese, and iron. The samples were treated with hydrofluoric acid, the residue taken up with hydrochloric acid, and the determination made by atomic absorption spectrometry. Substantial enrichment of the dusts in nickel and chromium during milling and dissemination was found. Cobalt and nickel content was different from that in UICC samples.

Exposure chambers for inhalation experiments with standard reference samples of asbestos of the International Union against cancer (UICC)

Five UICC samples are available for use in animal experiments to study the biological effects of different types of asbestos. They also provide reference standards for comparison with other asbestos samples. A low-cost animal exposure chamber of simple design is described which meets the requirements of inhalation experiments with the samples. The chambers can accommodate small animals in groups large enough for experiments to produce statistically valid results. The animals can be serviced without being removed from the chambers, so that they may be exposed for long periods with minimal contamination. Full protection of the operators is provided. This is essential as the reference samples contain a high proportion of dust of respirable size and must be treated as potentially dangerous. Details of the characteristics of dust clouds generated from the UICC samples in these chambers by a dust dispenser now commercially available are being published. To enable exposures to be compared it is recommended that dust monitoring equipment should include a gravimetric size selective sampler designed to collect the ‘respirable’ fraction of a dust cloud.

Analysis of Foreign Aerosol Produced in NO2-Rich Atmospheres of Animal Exposure Chambers

Analysis of Foreign Aerosol Produced in NO2-Rich Atmospheres of Animal Exposure Chambers

Analysis of foreign aerosol produced in NO2-rich atmospheres of animal exposure chambers.

Abstract A study was made of the composition of particulates generated in an exposure chamber in which dogs were exposed to an atmosphere charged with NO2 and ferric oxide. Ammonium nitrate appeared as the principal component.

Flame Emission Instrument for Selectively Monitoring Fe2O3 Aerosol in Animal Exposure Chambers

An instrument employing the principle of flame emission spectrophotometry has been constructed to selectively monitor the mass concentration of Fe2O3 aerosol in animal exposure chambers. The instrument was calibrated over the range from 0.3 to 1.6 mg/m3, and the maximum sensitivity was found to be about 0.3 μg of Fe2O3 aerosol per cubic meter of air.

Aerosol Studies with Avian Mycoplasma. 2. Infectivity of Mycoplasma gallisepticum for Chickens and Turkeys

Aerosol equipment. The aerosol exposure was accomplished with equipment and techniques previously described (1,2). The birds were exposed for 5 min followed by 5 min of air washing of the exposure chamber. An air sample was taken from the animal exposure chamber at the time each group of birds was exposed. These samples were immediately plated on solid modified French medium (3) in serial dilutions for quantitation. For the exposure of chickens to the aged aerosol, the exposure box was attached to the steel drum described in the first paper (2) by a 4-inch flexible tube. The exhaust hose to the filters and fan was attached to the other end of the exposure box. Animals. The chickens were White Leghorns from a mycoplasma-free flock under constant surveillance including regular testing for hemagglutination-inhibition (HI) antibodies against Mycoplasma gallisepticum. The turkeys were University Bronze birds hatched by the Poultry Science Department and reared by the Veterinary Science Department at the University of Wisconsin. These turkeys were serologically negative for HI antibodies against

Animal exposure chambers in air pollution studies.

The following requirements were considered mandatory in the design and installation of the animal exposure facility described in this report: a source of clean (CBR filtered) air supply; a constant flow of air; controls to vary air flow over a suitable range; instruments for accurately metering air flow; apparatus for injecting an aerosol or gaseous contaminant into the input stream; uniform distribution of the input air stream throughout the exposure zone; an air supply cooling system; signal devices to indicate failure of operating equipment; provision for exhausting air from the chambers; maintenance of slight negative pressure to prevent outward leakage from the exposure units; a means of conveniently cleaning the exposure chambers; facilities for taking representative samples of the exposure chamber atmosphere; appropriate sampling ports; ease of access to exposure chamber interior; suitable observation windows; and automatic control and recording of exposure chamber variables. 7 references, 2 figures, 5 tables.

EXPOSURE CHAMBER FOR ANIMALS AT CHANGED ATMOSPHERIC CONDITIONS.

An airtight exposure chamber is described in which mice can be kept continuously in an atmosphere with a high carbon dioxide percentage, or with a low or high oxygen percentage. Advantages of the apparatus described are the absence of moving parts inside the chamber and, in the experiments with a low or high percentage of oxygen, the absorption of carbon dioxide and water outside the chamber, permitting the continuous treatment of the animals. animal exposure chamber; carbon dioxide exposure; oxygen exposure Submitted on January 4, 1963