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

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.)

Engine-Operating Load Influences Diesel Exhaust Composition and Cardiopulmonary and Immune Responses

Background: The composition of diesel engine exhaust (DEE) varies by engine type and condition, fuel, engine operation, and exhaust after treatment such as particle traps. DEE has been shown to increase inflammation, susceptibility to infection, and cardiovascular responses in experimentally exposed rodents and humans. Engines used in these studies have been operated at idle, at different steady-state loads, or on variable-load cycles, but exposures are often reported only as the mass concentration of particulate matter (PM), and the effects of different engine loads and the resulting differences in DEE composition are unknown

Progress in Understanding the Toxicity of Gasoline and Diesel Engine Exhaust Emissions

To help guide heavy vehicle engine, fuel, and exhaust after-treatment technology development, the U.S. Department of Energy and the Lovelace Respiratory Research Institute are conducting research not addressed elsewhere on aspects of the toxicity of particulate engine emissions. Advances in these technologies that reduce diesel particulate mass emissions may result in changes in particle composition, and there is concern that the number of ultrafine (<0.1 micron) particles may increase. All present epidemiological and laboratory data on the toxicity of diesel emissions were derived from emissions of older-technology engines. New, short-term toxicity data are needed to make health-based choices among diesel technologies and to compare the toxicity of diesel emissions to those of other engine technologies. This research program has two facets: (1) development and use of short-term in vitro and in vivo toxicity assays for comparing the toxicities of gasoline and diesel exhaust emissions; and (2) determination of the disposition of inhaled ultrafine particles deposited in the lung. Responses of cultured cells, cultured lung slices, and rodent lungs to various types of particles were compared to develop an improved short-term toxicity screening capability. To date, chemical toxicity indicators of cultured human A549 cells and early inflammatory and cytotoxic indicators of rat lungs have given the best distinguishing capability. A study is now underway to determine the relative toxicities of exhaust samples from in-use diesel and gasoline engines. The samples are being collected under the direction of the National Renewable Energy Laboratory with support from DOE's Office of Heavy Vehicle Technologies. The ability to generate solid ultrafine particles and to trace their movement in the body as particles and soluble material was developed. Data from rodents suggest that ultrafine particles can move from the lung to the liver in particulate form. The quantitative disposition of inhaled ultrafine particles will be determined in rodents and nonhuman primates