Canines as sentinel species for assessing chronic exposures to air pollutants: Part 1. Respiratory pathology

A complex mixture of air pollutants is present in the ambient air in urban areas. People, animals, and vegetation are chronically and sequentially exp osed to outdoor pollutants, The objective of this first of 2 studies is to evaluate by light and electron microscopy the lungs of Mexico City dogs and compare the results to those of 3 less polluted cities in Mexico. One hund red fifty-two clinically healthy stray mongrel dogs (91 males/61 females), including 43 dogs from 3 less polluted cities, and 109 from southwest and n ortheast metropolitian Mexico City (SWMMC, NEMMC) were studied. Lungs of do gs living in Mexico City and Cuernavaca exhibited patchy chronic mononuclea r cell infiltrates along with macrophages loaded with particulate matter (P M) surrounding the bronchiolar walls and extending into adjacent vascular s tructures; bronchiolar epithelial and smooth muscle hyperplasia, peribronch iolar fibrosis, microthrombi, and capillary and venule polymorphonuclear le ukocytes (PMN) margination, Ultrafine PM was seen in alveolar type I and II cells, endothelial cells, interstitial macrophages (M theta), and intravas cular MB-like cells. Bronchoalveolar lavage showed significant numbers of a lveolar macrophages undergoing proliferation, Exposure to complex mixtures of pollutants-predominantly particulate matter and ozone-is causing lung st ructural changes induced by the sustained inflammatory process and resultin g in airway and vascular remodeling and altered repair, Cytokines released from both, circulating inflammatory and resident lung cells in response to endothelial and epithelial injury may be playing a role in the pathology de scribed here. Deep concern exists for the potential of an increasing rise i n lung diseases in child populations exposed to Mexico City's environment.