Rodent models of susceptibility: what is their place in inhalation toxicology?

There is renewed interest in inhalation toxicology regarding 'susceptibilit y' as associated with host variables, including genetics, age, diet, and di sease. This interest derives from epidemiology that shows air pollution-rel ated human mortality/morbidity, especially among individuals with cardiopul monary disease. Several animal models with experimental or genetically-base d cardiopulmonary diseases are now being incorporated into inhalation toxic ology studies to investigate mechanisms that underlie host susceptibility. However, current models have strengths and limitations as to how they mimic the essential features of human diseases. To date, animal models of pulmon ary hypertension, bronchitis, asthma, and cardiovascular disease; but not e mphysema, appear to exhibit greater susceptibility to air pollution particu late matter. As in humans, host susceptibility appears to involve multiple genetic and environmental factors, and is poorly understood, but the databa se of information is growing rapidly. As existing models gain wider use, ou r understanding of the models will improve and encourage refinements/develo pment of models that integrate both genetic and environmental factors to be tter mimic the human condition. (C) 2001 Elsevier Science B.V. All rights r eserved.