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Chronic Exposure to Ambient Levels of Urban Particles Affects Mouse Lung Development

2008; American Thoracic Society; Volume: 178; Issue: 7 Linguagem: Inglês

10.1164/rccm.200803-436oc

1535-4970

Thaís Mauad, Dolores Helena Rodriguez Ferreira Rivero, Regiani Carvalho-Oliveira, Ana Julia de Faria Coimbra Lichtenfels, Eliane Tigre Guimarães, Paulo Afonso de André, David I. Kasahara, Heloisa Maria de Siqueira Bueno, Paulo Hilário Nascimento Saldiva,

Noise Effects and Management

Rationale: Chronic exposure to air pollution has been associated with adverse effects on children's lung growth.Objectives: We analyzed the effects of chronic exposure to urban levels of particulate matter (PM) on selected phases of mouse lung development.Methods: The exposure occurred in two open-top chambers (filtered and nonfiltered) placed 20 m from a street with heavy traffic in São Paulo, 24 hours/day for 8 months. There was a significant reduction of the levels of PM2.5 inside the filtered chamber (filtered = 2.9 ± 3.0 μg/m3, nonfiltered = 16.8 ± 8.3 μg/m3; P = 0.001). At this exposure site, vehicular sources are the major components of PM2.5 (PM ≤ 2.5μm). Exposure of the parental generation in the two chambers occurred from the 10th to the 120th days of life. After mating and birth of offspring, a crossover of mothers and pups occurred within the chambers, resulting in four groups of pups: nonexposed, prenatal, postnatal, and pre+postnatal. Offspring were killed at the age of 15 (n = 42) and 90 (n = 35) days; lungs were analyzed by morphometry for surface to volume ratio (as an estimator of alveolization). Pressure–volume curves were performed in the older groups, using a 20-ml plethysmograph.Measurements and Main Results: Mice exposed to PM2.5 pre+postnatally presented a smaller surface to volume ratio when compared with nonexposed animals (P = 0.036). The pre+postnatal group presented reduced inspiratory and expiratory volumes at higher levels of transpulmonary pressure (P = 0.001). There were no differences among prenatal and postnatal exposure and nonexposed animals.Conclusions: Our data provide anatomical and functional support to the concept that chronic exposure to urban PM affects lung growth.