Role of inhalation studies with animals in defining human health risks for vehicle and power plant emissions.

Abstract

Automotive vehicles and power plants using fossil fuels emit a complex array of gases and particulate material. The physical and chemical characteristics of these emissions vary markedly between sources and comprise only a portion of the contributors to air pollution exposure of people. Further, it is well recognized that a single form of self-inflicted air pollution, cigarette smoking, is the dominant cause of air pollution-induced disease. These factors minimize our potential for developing an adequate understanding of the health effects of vehicle and power plant emissions by studying only people. The alternative is to use the human data to the extent feasible and complement it with information gained in studies with macromolecules, organelles, cells, tissues and whole animals. Within this context, this paper reviews the use of inhalation studies with animals for defining human health risks of airborne materials, especially particulate materials. The major areas covered are: the fate of inhaled materials, the pathogenesis of disease induced by inhaled materials and long-term animal studies to identify late-occurring effects. Emphasis is placed on the utility of studies in whole animals as integrative models in which the multiple processes such as xenobiotic metabolism, cell injury, repair, transformation and promotion under the influence of many host factors interact in a manner that may not be directly observed in isolated cells or tissues.

Consensus report: mutagenicity and carcinogenicity of car exhausts and coal combustion emissions

“…When larger quantities of diesel exhaust particles are deposited in the lungs of rats, either by exposure to high concentrations of exhaust or by prolonged exposure to more moderate concentrations, the clearance of the particles from the alveolar region of the lungs may be impaired. As a result, greater quantities of particles are retained in the lung for longer periods of time (hundreds of days) than would be predicted from studies of lower exposure concentrations (6,101,102).…”

“…The retention half time of diesel particles in the lungs of rats exposed at low concentrations is on the order of a hundred days (6,101,102). Rodents generally clear other types of particles from the lungs more rapidly than is observed in the dog or man (103,104).…”

“…Data on the retention of several trace elements in fly ash has been obtained using neutron activation techniques (102,108,107). From these studies, it appears that the primary factor governing the retention of the trace elements is the dissolution rate of the matrix of the particles (102).…”

“…From these studies, it appears that the primary factor governing the retention of the trace elements is the dissolution rate of the matrix of the particles (102).…”

“…There are data available on the retention in the lung of only a limited number of organic products of combustion (or perhaps more correctly stated, products of incomplete combustion) deposited in the lungs either by inhalation exposure or intratracheal instillation (102). The retention of the organic compounds in the lung and the concentrations reaching other tissues was influenced by the physical characteristics of the deposited material and the specific compound administered.…”