Inhalation exposure of animals.

Relative advantages and disadvantages and important design criteria for various exposure methods are presented. Five types of exposures are discussed: whole-body chambers, head-only exposures, nose or mouth-only methods, lung-only exposures, and partial-lung exposures. Design considerations covered include: air cleaning and conditioning; construction materials; losses of exposure materials; evenness of exposure; sampling biases; animal observation and care; noise and vibration control, safe exhausts, chamber loading, reliability, pressure fluctuations; neck seals, masks, animal restraint methods; and animal comfort. Ethical considerations in use of animals in inhalation experiments are also discussed

Health Effects of Subchronic Inhalation of Simulated Downwind Coal Combustion Emissions

The purpose of this project was to conduct a comprehensive laboratory-based evaluation of selected respiratory and cardiac health hazards of subchronic (up to 6 months) inhalation of simulated key components of 'downwind plume' emissions of coal combustion. This project was performed as an integral part of a joint government-industry program termed the 'National Environmental Respiratory Center' (NERC), which is aimed at disentangling the roles of different physical-chemical air pollutants and their sources in the health effects associated statistically with air pollution. The characterization of the exposure atmosphere and the health assays were identical to those employed in the NERC protocols used to evaluate other pollution source emissions, such as diesel, gasoline, and wood combustion. The project had two phases, each encompassing multiple tasks. Guidelines for the composition of the exposure atmosphere were set by consensus of an expert workshop. Development of the capability to generate the exposure atmosphere and pilot studies of the comparative exposure composition using two coal types were accomplished in Phase 1. In Phase 2, the toxicological study was conducted using Powder River Basin Sub-bituminous coal. NETL provided 50% support for the work in Phase 1 and had intended to provide 20% support for the work in Phase 2. Phase 1 is completed and Phase 2 is in the final stages. All animal exposures were completed without incident, and the composition of the exposure atmospheres met the targets. All of the health sample collections are completed, but some samples remain to be analyzed. Data summaries and final statistical analysis of results remain to be completed. The goal is to submit all publications before the end of FY-08. Repeated exposure to simulated downwind coal emissions caused some significant health effects, but the number of effects tended to be fewer than those caused by the other NERC exposures (diesel and gasoline emissions and hardwood smoke). the lowest concentration, a dilution containing approximately 100 {micro}g particulate matter (PM)/m{sup 3}, was a no-effects level for nearly all measured variables. One of the most interesting findings was that few, if indeed any, health outcomes appeared to be caused by the PM component of the exposure. This finding strongly suggests that PM simulating the major contributions of coal combustion to environmental PM is of very low toxicity

Inhalation exposure methodology.

Modern man is being confronted with an ever-increasing inventory of potentially toxic airborne substances. Exposures to these atmospheric contaminants occur in residential and commercial settings, as well as in the workplace. In order to study the toxicity of such materials, a special technology relating to inhalation exposure systems has evolved. The purpose of this paper is to provide a description of the techniques which are used in exposing laboratory subjects to airborne particles and gases. The various modes of inhalation exposure (whole body, head only, nose or mouth only, etc.) are described at length, including the advantages and disadvantages inherent to each mode. Numerous literature citations are included for further reading. Among the topics briefly discussed are the selection of appropriate animal species for toxicological testing, and the types of inhalation studies performed (acute, chronic, etc.)

Effects of Low Sulfur Fuel and a Catalyzed Particle Trap on the Composition and Toxicity of Diesel Emissions

In this study we compared a “baseline” condition of uncontrolled diesel engine exhaust (DEE) emissions generated with current (circa 2003) certification fuel to an emissions-reduction (ER) case with low sulfur fuel and a catalyzed particle trap. Lung toxicity assessments (resistance to respiratory viral infection, lung inflammation, and oxidative stress) were performed on mice (C57Bl/6) exposed by inhalation (6 hr/day for 7 days). The engine was operated identically (same engine load) in both cases, and the inhalation exposures were conducted at the same exhaust dilution rate. For baseline DEE, this dilution resulted in a particle mass (PM) concentration of approximately 200 μg/m(3) PM, whereas the ER reduced the PM and almost every other measured constituent [except nitrogen oxides (NO(x))] to near background levels in the exposure atmospheres. These measurements included PM, PM size distribution, PM composition (carbon, ions, elements), NO(x), carbon monoxide, speciated/total volatile hydrocarbons, and several classes of semi-volatile organic compounds. After exposure concluded, one group of mice was immediately sacrificed and assessed for inflammation and oxidative stress in lung homogenate. Another group of mice were intratracheally instilled with respiratory syncytial virus (RSV), and RSV lung clearance and inflammation was assessed 4 days later. Baseline DEE produced statistically significant biological effects for all measured parameters. The use of low sulfur fuel and a catalyzed trap either completely or nearly eliminated the effects